Как правильно пишется свиной грипп

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Здравствуйте! Корректно ли писать коронавирус COVID-19? Разве это не плеоназм?

Ответ справочной службы русского языка

Ответить на Ваш вопрос нам помогла Александра Борисова, кандидат химических наук, научный журналист.

Коронавирус – это группа вирусов. Вирус, который беспокоит сегодня весь мир, – SARS-CoV-2. (Известны также коронавирус SARS-CoV, возбудитель атипичной пневмонии, первый случай заболевания которой был зарегистрирован в 2002 году; коронавирус MERS-CoV, возбудитель ближневосточного респираторного синдрома, вспышка которого произошла в 2015 году.) COVID-19 – болезнь, которую вызывает вирус SARS-CoV-2. В разговорной речи всю эту группу понятий можно называть коронавирусом.

Сравните с названиями других вирусов и заболеваний.

ВИЧ – это вирус. СПИД – это болезнь, которую вызывает ВИЧ.

Грипп – это группа вирусов. Также называют и болезнь, которую вызывает вирус гриппа. А вот свиной грипп, птичий грипп – это уже типы вирусов гриппа (их еще иногда обозначают буквами и цифрами, например свиной грипп H1N1). 

Рекомендации по употреблению названий коронавирус и COVID-19 можно дать такие.

COVID-19 корректно говорить о болезни, но не о вирусе. Коронавирусом можно назвать и вирус, и болезнь (ср. пример с гриппом). 

То есть можно сказать о болезни: У него коронавирус. А если нужно подчеркнуть, что речь идет о самом вирусе, – тогда правильно: коронавирус SARS-CoV-2.

Однако нужно учитывать, что коронавирус в значении ‘болезнь’ – это разговорное, бытовое употребление. Сочетание  термина COVID-19 со словом коронавирус в бытовом значении ‘болезнь’ невозможно, а в терминологическом значении ‘вирус’ неправильно. Нельзя болезнь (комплекс симптомов) называть вирусом. Но допустимо сочетание коронавирусная инфекция COVID-19, потому что инфекция – это болезнь.

Здравствуйте! Можно ли в меню написать «Стейк из шеи свинины»?

Ответ справочной службы русского языка

Поскольку свинина — это мясо в целом, а не туша, сочетание шея свинины некорректно. Лучше: стейк из свиной шеи.

Добрый день! Подскажите, пожалуйста, можно ли употреблять слово «фарш» во множественном числе? Например, в выражениях типа: «При этом в *фарше* «Пупкинский» и «Жирныф дом» обнаружены антибиотики, а повышенное содеожание жира нашли в *фарше* «Говяжий» (Самара) и «Свиной»». С одной стороны, почему бы и нет, с другой — как-то неожиданно. Заранее спасибо)

Ответ справочной службы русского языка

Слова вроде фарш употребляются во множественном числе нечасто, в основном в профессиональной речи. В обычных текстах для широкой аудитории рекомендуется использовать форму единственного числа:  …в фарше «Говяжий» (Самара) и «Свиной».

Почему свиной грипп не нужно заключать в кавычки (согласно вашим рекомендациям)?

Ответ справочной службы русского языка

Это сочетание часто употребляется в последнее время, оно перестало быть новым, необычным, непривычным, что, по нашему мнению, и дает основания не заключать его в кавычки.

Как звучит поговорка вторая половина которой выглядит примерно так: «…а кому свиной хрящик»?

Ответ справочной службы русского языка

В «Толковом словаре русского языка» под ред. Д. Н. Ушакова (1935–1940) приводятся (в словарной статье хрящик) такие примеры: Одному нравится арбуз, другому свиной хрящик (Салтыков-Щедрин); У всякого свой вкус: кто любит дыню, а кто арбуз, а кто — свиной хрящик (посл.).

Почему в прилагательном свиной пишется одна -н- в суффиксе, или это корень?

Ответ справочной службы русского языка

В слове свиной корень свин-. В этом слове пишется одна буква н, т. к. оно не содержит суффикса -н-.

В слове «свиной» есть нулевой суффикс?

Ответ справочной службы русского языка

Да.

Здравствуйте! Будьте добры, подскажите, почему в слове «свиной» пишется одна «н»?
Картина+н=картиННый; истина+н=истиННый. А свиНой?

Ответ справочной службы русского языка

В прилагательных юный и свиной пишется одно Н, поскольку эти слова не содержат суффикса -н-. Обычно написание этих слов предлагается запомнить.

Cвиной грипп. Где ставить кавычки?

Ответ справочной службы русского языка

Корректно без кавычек: свиной грипп.

Почему в прилагательном «свиной» пишется одна буква Н? И можно ли проводить здесь аналогию с прилагательным «юный»? Заранее благодарна за ответ.

Ответ справочной службы русского языка

Слово свиной — словарное, его написание нужно запомнить. Юный — непроизводное прилагательное; это слово пишется с одной Н, так как в нем нет суффикса Н.

Здравствуйте! Можно задать вопрос? Почему в слове свиной пишется одна н, хотя по правилам, если основа слова заканчивается на н, то пишется два н? В исключениях данное слово не значится! Спасибо заранее.

Ответ справочной службы русского языка

В прилагательных юный и свиной пишется одно Н, поскольку эти слова не содержат суффикса -н-. Обычно написание этих слов предлагается запомнить.

Почему в слове «свиной» пишется одна буква «н»?

Ответ справочной службы русского языка

См. ответ № 187937 .

Скажите, пожалуйста, какой может быть синоним к слову «навоз», более приемлемый для употребления в деловой литературе (анализ компаний — производителей мяса).

Ответ справочной службы русского языка

Навоз — слово вполне литературное. Как вариант — коровий (овечий, свиной и т. п.) помет.

Свиной грипп (англ. Swine influenza) — условное название заболевания людей и животных, вызываемого штаммами вируса гриппа. Штаммы, ассоциированные со вспышками т. н. «свиного гриппа», обнаружены среди вирусов гриппа серотипа C и подтипов серотипа А (А/H1N1, А/H1N2, А/H3N1, А/H3N2 и А/H2N3). Эти штаммы известны под общим названием «вирус свиного гриппа». Свиной грипп распространён среди домашних свиней в США, Мексике, Канаде, Южной Америке, Европе, Кении, материковом Китае, Тайване, Японии и других странах Азии. При этом вирус может циркулировать в среде людей, птиц и др. видов; этот процесс сопровождается его мутациями.

Все значения словосочетания «свиной грипп»

• птичий грипп
• вирус гриппа
• эпидемия гриппа
• испанский грипп
• пандемия гриппа
• (ещё синонимы…)

• грязь
• рулька
• челмедведосвин
• домашний скот
• мясо
• (ещё ассоциации…)

• болезнь
• осложнение
• температура
• болезни
• врач
• (ещё ассоциации…)

• Разбор по составу слова «свинья»
• Разбор по составу слова «грипп»

• Как правильно пишется слово «свинья»
• Как правильно пишется слово «грипп»

Swine influenza
Other names	Pig influenza, swine flu, hog flu, pig flu
Electron microscope image of the reassorted H1N1 influenza virus photographed at the CDC Influenza Laboratory. The viruses are 80–120 nanometres in diameter.[1]
Specialty	Infectious disease

Swine influenza is an infection caused by any of several types of swine influenza viruses. Swine influenza virus (SIV) or swine-origin influenza virus (S-OIV) refers to any strain of the influenza family of viruses that is endemic in pigs.^[2] As of 2009, identified SIV strains include influenza C and the subtypes of influenza A known as H1N1, H1N2, H2N1, H3N1, H3N2, and H2N3.^[3]

The swine influenza virus is common throughout pig populations worldwide. Transmission of the virus from pigs to humans is rare, and does not always lead to human illness, often resulting only in the production of antibodies in the blood. If transmission causes human human, it is called zoonotic swine flu. People with regular exposure to pigs are at increased risk of swine flu infections.

Around the mid-20th century, identification of influenza sub-types was made possible, allowing accurate diagnosis of transmission to humans. Since then, only 50 such transmissions have been confirmed. These strains of swine flu rarely pass from human to human. Symptoms of zoonotic swine flu in humans are similar to those of influenza and of influenza-like illness and include chills, fever, sore throat, muscle pains, severe headache, coughing, weakness, shortness of breath, and general discomfort.

It is estimated that, in the 2009 flu pandemic, 11–21% of the then global population (of about 6.8 billion), equivalent to around 700 million to 1.4 billion people, contracted the illness—more, in absolute terms, than the Spanish flu pandemic. There were 18,449 confirmed fatalities. However, in a 2012 study, the CDC estimated more than 284,000 possible fatalities worldwide, with numbers ranging from 150,000 to 575,000.^[4][5]
In August 2010, the World Health Organization declared the swine flu pandemic officially over.^[6][7]

Subsequent cases of swine flu were reported in India in 2015, with over 31,156 positive test cases and 1,841 deaths.

Signs and symptoms[edit]

In pigs, a swine influenza infection produces fever, lethargy, discharge from the nose or eyes, sneezing, coughing, difficulty breathing, eye redness or inflammation, and decreased appetite.^[8] In some cases the infection can cause miscarriage. However, it is possible that infected pigs may not exhibit any symptoms.^[9] Although mortality is usually low (around 1–4%),^[2] the virus can cause weight loss and poor growth, in turn causing economic loss to farmers.^[8] Infected pigs can lose up to 12 pounds of body weight over a three- to four-week period.^[8] Swine have receptors to which both avian and mammalian influenza viruses are able to bind; this leads to the virus being able to evolve and mutate into different forms.^[10] Influenza A is responsible for infecting swine, and was first identified in 1918.^[10] Pigs have often been seen as «mixing vessels», which help to change and evolve strains of disease that are then passed on to other mammals, such as humans.^[10]

Humans[edit]

Direct transmission of a swine flu virus from pigs to humans is occasionally possible (zoonotic swine flu).^[12] In all, 50 cases are known to have occurred since the first report in medical literature in 1958, which have resulted in a total of six deaths.^[13] Of these six people, one was pregnant, one had leukemia, one had Hodgkin’s lymphoma and two were known to be previously healthy. One of these had unknown whereabouts.^[13] Despite these apparently low numbers of infections, the true rate of infection may be higher, since most cases only cause a very mild disease, and will probably never be reported or diagnosed.^[13]

According to the United States Centers for Disease Control and Prevention (CDC), in humans the symptoms of the 2009 «swine flu» H1N1 virus are similar to influenza and influenza-like illness in general. Symptoms include fever, cough, sore throat, watery eyes, body aches, shortness of breath, headache, weight loss, chills, sneezing, runny nose, coughing, dizziness, abdominal pain, lack of appetite, and fatigue. The 2009 outbreak also had an increased percentage of patients reporting diarrhea and vomiting. The 2009 H1N1 virus is not zoonotic swine flu, as it is not transmitted from pigs to humans, but from person to person through airborne droplets.^[15]

Because these symptoms are not specific to swine flu, a differential diagnosis of probable swine flu requires not only symptoms, but also a high likelihood of swine flu due to the person’s recent and past medical history. For example, during the 2009 swine flu outbreak in the United States, the CDC advised physicians to «consider swine influenza infection in the differential diagnosis of patients with acute febrile respiratory illness who have either been in contact with persons with confirmed swine flu, or who were in one of the five U.S. states that have reported swine flu cases or in Mexico during the seven days preceding their illness onset.»^[16] A diagnosis of confirmed swine flu requires laboratory testing of a respiratory sample (a simple nose and throat swab).^[16]

The most common cause of death is respiratory failure. Other causes of death are pneumonia (leading to sepsis),^[17] high fever (leading to neurological problems), dehydration (from excessive vomiting and diarrhea), electrolyte imbalance and kidney failure.^[18] Fatalities are more likely in young children and the elderly.^{[citation needed]}

Virology[edit]

Transmission[edit]

Between pigs[edit]

Influenza is quite common in pigs, with about half of breeding pigs having been exposed to the virus in the US.^[19] Antibodies to the virus are also common in pigs in other countries.^[19]

The main route of transmission is through direct contact between infected and uninfected animals.^[8] These close contacts are particularly common during animal transport. Intensive farming may also increase the risk of transmission, as the pigs are raised in very close proximity to each other.^[20][21] The direct transfer of the virus probably occurs either by pigs touching noses, or through dried mucus. Airborne transmission through the aerosols produced by pigs coughing or sneezing are also an important means of infection.^[8] The virus usually spreads quickly through a herd, infecting all the pigs within just a few days.^[2] Transmission may also occur through wild animals, such as wild boar, which can spread the disease between farms.^[22]

To humans[edit]

People who work with poultry and swine, especially those with intense exposures, are at increased risk of zoonotic infection with influenza virus endemic in these animals, and constitute a population of human hosts in which zoonosis and reassortment can co-occur.^[23] Vaccination of these workers against influenza and surveillance for new influenza strains among this population may therefore be an important public health measure.^[24] Transmission of influenza from swine to humans who work with swine was documented in a small surveillance study performed in 2004 at the University of Iowa.^[25] This study, among others, forms the basis of a recommendation that people whose jobs involve handling poultry and swine be the focus of increased public health surveillance.^[23] Other professions at particular risk of infection are veterinarians and meat processing workers, although the risk of infection for both of these groups is lower than that of farm workers.^[26]

Interaction with avian H5N1 in pigs[edit]

Pigs are unusual as they can be infected with influenza strains that usually infect three different species: pigs, birds, and humans.^[27] Pigs are a host where influenza viruses might exchange genes, producing new and dangerous strains.^[27] Avian influenza virus H3N2 is endemic in pigs in China and has been detected in pigs in Vietnam, increasing fears of the emergence of new variant strains.^[28] H3N2 evolved from H2N2 by antigenic shift.^[29] In August 2004, researchers in China found H5N1 in pigs.^[30]

These H5N1 infections may be quite common; in a survey of 10 apparently healthy pigs housed near poultry farms in West Java, where avian flu had broken out, five of the pig samples contained the H5N1 virus. The Indonesian government has since found similar results in the same region. Additional tests of 150 pigs outside the area were negative.^[31][32]

Structure[edit]

The influenza virion is roughly spherical. It is an enveloped virus; the outer layer is a lipid membrane which is taken from the host cell in which the virus multiplies. Inserted into the lipid membrane are «spikes», which are proteins—actually glycoproteins, because they consist of protein linked to sugars—known as HA (hemagglutinin) and NA (neuraminidase). These are the proteins that determine the subtype of influenza virus (A/H1N1, for example). The HA and NA are important in the immune response against the virus; antibodies (proteins made to combat infection) against these spikes may protect against infection. The NA protein is the target of the antiviral drugs Relenza and Tamiflu. Also embedded in the lipid membrane is the M2 protein, which is the target of the antiviral adamantanes amantadine and rimantadine.^{[citation needed]}

Classification[edit]

Of the three genera of influenza viruses that cause human flu, two also cause influenza in pigs, with influenza A being common in pigs and influenza C being rare.^[33] Influenza B has not been reported in pigs. Within influenza A and influenza C, the strains found in pigs and humans are largely distinct, although because of reassortment there have been transfers of genes among strains crossing swine, avian, and human species boundaries.^{[citation needed]}

Influenza C[edit]

Influenza viruses infect both humans and pigs, but do not infect birds.^[34] Transmission between pigs and humans have occurred in the past.^[35] For example, influenza C caused small outbreaks of a mild form of influenza amongst children in Japan^[36] and California.^[36] Because of its limited host range and the lack of genetic diversity in influenza C, this form of influenza does not cause pandemics in humans.^[37]

Influenza A[edit]

Swine influenza is caused by influenza A subtypes H1N1,^[38] H1N2,^[38] H2N3,^[39] H3N1,^[40] and H3N2.^[38] In pigs, four influenza A virus subtypes (H1N1, H1N2, H3N2 and H7N9) are the most common strains worldwide.^[8] In the United States, the H1N1 subtype was exclusively prevalent among swine populations before 1998; however, since late August 1998, H3N2 subtypes have been isolated from pigs. As of 2004, H3N2 virus isolates in US swine and turkey stocks were triple reassortants, containing genes from human (HA, NA, and PB1), swine (NS, NP, and M), and avian (PB2 and PA) lineages.^[41] In August 2012, the Center for Disease Control and Prevention confirmed 145 human cases (113 in Indiana, 30 in Ohio, one in Hawaii and one in Illinois) of H3N2v since July 2012.^[42] The death of a 61-year-old Madison County, Ohio woman is the first in the USA associated with a new swine flu strain. She contracted the illness after having contact with hogs at the Ross County Fair.^[43]

Diagnosis[edit]

The CDC recommends real-time PCR as the method of choice for diagnosing H1N1.^[44] The oral or nasal fluid collection and RNA virus-preserving filter-paper card is commercially available.^[45] This method allows a specific diagnosis of novel influenza (H1N1) as opposed to seasonal influenza. Near-patient point-of-care tests are in development.^[46]

Prevention[edit]

Prevention of swine influenza has three components: prevention in pigs, prevention of transmission to humans, and prevention of its spread among humans. Proper handwashing techniques can prevent the virus from spreading. Avoid touching the eyes, nose, or mouth. Stay away from others who display symptoms of the cold or flu and avoid contact with others when displaying symptoms.^{[citation needed]}

Swine[edit]

Methods of preventing the spread of influenza among swine include facility management, herd management, and vaccination (ATCvet code: QI09AA03 (WHO)). Because much of the illness and death associated with swine flu involves secondary infection by other pathogens, control strategies that rely on vaccination may be insufficient.^{[citation needed]}

Control of swine influenza by vaccination has become more difficult in recent decades, as the evolution of the virus has resulted in inconsistent responses to traditional vaccines. Standard commercial swine flu vaccines are effective in controlling the infection when the virus strains match enough to have significant cross-protection, and custom (autogenous) vaccines made from the specific viruses isolated are created and used in the more difficult cases.^[47][48]
Present vaccination strategies for SIV control and prevention in swine farms typically include the use of one of several bivalent SIV vaccines commercially available in the United States. Of the 97 recent H3N2 isolates examined, only 41 isolates had strong serologic cross-reactions with antiserum to three commercial SIV vaccines. Since the protective ability of influenza vaccines depends primarily on the closeness of the match between the vaccine virus and the epidemic virus, the presence of nonreactive H3N2 SIV variants suggests current commercial vaccines might not effectively protect pigs from infection with a majority of H3N2 viruses.^[13][49] The United States Department of Agriculture researchers say while pig vaccination keeps pigs from getting sick, it does not block infection or shedding of the virus.^[50]

Facility management includes using disinfectants and ambient temperature to control viruses in the environment. They are unlikely to survive outside living cells for more than two weeks, except in cold (but above freezing) conditions, and are readily inactivated by disinfectants.^[2] Herd management includes not adding pigs carrying influenza to herds that have not been exposed to the virus. The virus survives in healthy carrier pigs for up to three months and can be recovered from them between outbreaks. Carrier pigs are usually responsible for the introduction of SIV into previously uninfected herds and countries, so new animals should be quarantined.^[19] After an outbreak, as immunity in exposed pigs wanes, new outbreaks of the same strain can occur.^[2]

Humans[edit]

Prevention of pig-to-human transmission

Swine can be infected by both avian and human flu strains of influenza, and therefore are hosts where the antigenic shifts can occur that create new influenza strains.^{[citation needed]}

The transmission from swine to humans is believed to occur mainly in swine farms, where farmers are in close contact with live pigs. Although strains of swine influenza are usually not able to infect humans, it may occasionally happen, so farmers and veterinarians are encouraged to use face masks when dealing with infected animals. The use of vaccines on swine to prevent their infection is a major method of limiting swine-to-human transmission. Risk factors that may contribute to the swine-to-human transmission include smoking and, especially, not wearing gloves when working with sick animals, thereby increasing the likelihood of subsequent hand-to-eye, hand-to-nose, or hand-to-mouth transmission.^[51]

Prevention of human-to-human transmission

Influenza spreads between humans when infected people cough or sneeze, then other people breathe in the virus or touch something with the virus on it and then touch their own face.^[52] «Avoid touching your eyes, nose or mouth. Germs spread this way.»^[53] Swine flu cannot be spread by pork products, since the virus is not transmitted through food.^[52] The swine flu in humans is most contagious during the first five days of the illness, although some people, most commonly children, can remain contagious for up to ten days. Diagnosis can be made by sending a specimen, collected during the first five days, for analysis.^[54]

Recommendations to prevent the spread of the virus among humans include using standard infection control, which includes frequent washing of hands with soap and water or with alcohol-based hand sanitizers, especially after being out in public.^[55] Chance of transmission is also reduced by disinfecting household surfaces, which can be done effectively with a diluted chlorine bleach solution.^[56]

Experts agree hand-washing can help prevent viral infections, including ordinary and swine flu infections. Also, avoiding touching one’s eyes, nose, or mouth with one’s hands helps to prevent the flu.^[53] Influenza can spread in coughs or sneezes, but an increasing body of evidence shows small droplets containing the virus can linger on tabletops, telephones, and other surfaces and be transferred via the fingers to the eyes, nose, or mouth. Alcohol-based gel or foam hand sanitizers work well to destroy viruses and bacteria. Anyone with flu-like symptoms, such as a sudden fever, cough, or muscle aches, should stay away from work or public transportation and should contact a doctor for advice.^[57]

Social distancing, another tactic, is staying away from other people who might be infected, and can include avoiding large gatherings, spreading out a little at work, or perhaps staying home and lying low if an infection is spreading in a community. Public health and other responsible authorities have action plans which may request or require social distancing actions, depending on the severity of the outbreak.^{[citation needed]}

Vaccination[edit]

Vaccines are available for different kinds of swine flu. The U.S. Food and Drug Administration (FDA) approved the new swine flu vaccine for use in the United States on September 15, 2009.^[58] Studies by the National Institutes of Health show a single dose creates enough antibodies to protect against the virus within about 10 days.^[59]

In the aftermath of the 2009 pandemic, several studies were conducted to see who received influenza vaccines. These studies show that whites are much more likely to be vaccinated for seasonal influenza and for the H1N1 strain than African Americans ^[60] This could be due to several factors. Historically, there has been mistrust of vaccines and of the medical community from African Americans. Many African Americans do not believe vaccines or doctors to be effective. This mistrust stems from the exploitation of the African American communities during studies like the Tuskegee study. Additionally, vaccines are typically administered in clinics, hospitals, or doctor’s offices. Many people of lower socioeconomic status are less likely to receive vaccinations because they do not have health insurance.^{[citation needed]}

Surveillance[edit]

Although there is no formal national surveillance system in the United States to determine what viruses are circulating in pigs,^[61] an informal surveillance network in the United States is part of a world surveillance network.^[62]

Treatment[edit]

Swine[edit]

As swine influenza is rarely fatal to pigs, little treatment beyond rest and supportive care is required.^[19] Instead, veterinary efforts are focused on preventing the spread of the virus throughout the farm or to other farms.^[8] Vaccination and animal management techniques are most important in these efforts. Antibiotics are also used to treat the disease, which, although they have no effect against the influenza virus, do help prevent bacterial pneumonia and other secondary infections in influenza-weakened herds.^[19]

In Europe the avian-like H1N1 and the human-like H3N2 and H1N2 are the most common influenza subtypes in swine, of which avian-like H1N1 is the most frequent. Since 2009 another subtype, pdmH1N1(2009), emerged globally and also in European pig population. The prevalence varies from country to country but all of the subtypes are continuously circulating in swine herds.^[63]
In the EU region whole-virus vaccines are available which are inactivated and adjuvanted. Vaccination of sows is common practice and reveals also a benefit to young pigs by prolonging the maternally level of antibodies. Several commercial vaccines are available including a trivalent one being used in sow vaccination and a vaccine against pdmH1N1(2009).^[64] In vaccinated sows multiplication of viruses and virus shedding are significantly reduced.^{[citation needed]}

Humans[edit]

If a human becomes sick with swine flu, antiviral drugs can make the illness milder and make the patient feel better faster. They may also prevent serious flu complications. For treatment, antiviral drugs work best if started soon after getting sick (within two days of symptoms). Beside antivirals, supportive care at home or in a hospital focuses on controlling fevers, relieving pain and maintaining fluid balance, as well as identifying and treating any secondary infections or other medical problems. The U.S. Centers for Disease Control and Prevention recommends the use of oseltamivir (Tamiflu) or zanamivir (Relenza) for the treatment and/or prevention of infection with swine influenza viruses; however, the majority of people infected with the virus make a full recovery without requiring medical attention or antiviral drugs.^[65] The virus isolated in the 2009 outbreak have been found resistant to amantadine and rimantadine.^[66]

History[edit]

Pandemics[edit]

Swine influenza was first proposed to be a disease related to human flu during the 1918 flu pandemic, when pigs became ill at the same time as humans.^[67] The first identification of an influenza virus as a cause of disease in pigs occurred about ten years later, in 1930.^[68] For the following 60 years, swine influenza strains were almost exclusively H1N1. Then, between 1997 and 2002, new strains of three different subtypes and five different genotypes emerged as causes of influenza among pigs in North America. In 1997–1998, H3N2 strains emerged. These strains, which include genes derived by reassortment from human, swine and avian viruses, have become a major cause of swine influenza in North America. Reassortment between H1N1 and H3N2 produced H1N2. In 1999 in Canada, a strain of H4N6 crossed the species barrier from birds to pigs, but was contained on a single farm.^[68]

The H1N1 form of swine flu is one of the descendants of the strain that caused the 1918 flu pandemic.^[69][70] As well as persisting in pigs, the descendants of the 1918 virus have also circulated in humans through the 20th century, contributing to the normal seasonal epidemics of influenza.^[70] However, direct transmission from pigs to humans is rare, with only 12 recorded cases in the U.S. since 2005.^[71] Nevertheless, the retention of influenza strains in pigs after these strains have disappeared from the human population might make pigs a reservoir where influenza viruses could persist, later emerging to reinfect humans once human immunity to these strains has waned.^[72]

Swine flu has been reported numerous times as a zoonosis in humans, usually with limited distribution, rarely with a widespread distribution. Outbreaks in swine are common and cause significant economic losses in industry, primarily by causing stunting and extended time to market. For example, this disease costs the British meat industry about £65 million every year.^[73]

1918[edit]

The 1918 flu pandemic in humans was associated with H1N1 and influenza appearing in pigs;^[70] this may reflect a zoonosis either from swine to humans, or from humans to swine. Although it is not certain in which direction the virus was transferred, some evidence suggests, in this case, pigs caught the disease from humans.^[67] For instance, swine influenza was only noted as a new disease of pigs in 1918, after the first large outbreaks of influenza amongst people.^[67] Although a recent phylogenetic analysis of more recent strains of influenza in humans, birds, animals, and many others, including swine, suggests the 1918 outbreak in humans followed a reassortment event within a mammal,^[74] the exact origin of the 1918 strain remains elusive.^[75] It is estimated that anywhere from 50 to 100 million people were killed worldwide.^[70][76]

U.S. 2009[edit]

The swine flu was initially seen in the US in April 2009, where the strain of the particular virus was a mixture from 3 types of strains.^[77] Six of the genes are very similar to the H1N2 influenza virus that was found in pigs around 2000.^[77]

Outbreaks[edit]

1976 U.S.[edit]

On February 5, 1976, a United States army recruit at Fort Dix said he felt tired and weak. He died the next day, and four of his fellow soldiers were later hospitalized. Two weeks after his death, health officials announced the cause of death was a new strain of swine flu. The strain, a variant of H1N1, is known as A/New Jersey/1976 (H1N1). It was detected only from January 19 to February 9 and did not spread beyond Fort Dix.^[78]

This new strain appeared to be closely related to the strain involved in the 1918 flu pandemic. Moreover, the ensuing increased surveillance uncovered another strain in circulation in the U.S.: A/Victoria/75 (H3N2), which spread simultaneously, also caused illness, and persisted until March.^[78] Alarmed public health officials decided action must be taken to head off another major pandemic, and urged President Gerald Ford that every person in the U.S. be vaccinated for the disease.^[79]

The vaccination program was plagued by delays and public relations problems.^[80] On October 1, 1976, immunizations began, and three senior citizens died soon after receiving their injections. This resulted in a media outcry that linked these deaths to the immunizations, despite the lack of any proof the vaccine was the cause. According to science writer Patrick Di Justo, however, by the time the truth was known—that the deaths were not proven to be related to the vaccine—it was too late. «The government had long feared mass panic about swine flu—now they feared mass panic about the swine flu vaccinations.» This became a strong setback to the program.^[81]

There were reports of Guillain–Barré syndrome (GBS), a paralyzing neuromuscular disorder, affecting some people who had received swine flu immunizations. Although whether a link exists is still not clear, this syndrome may be a side effect of influenza vaccines. As a result, Di Justo writes, «the public refused to trust a government-operated health program that killed old people and crippled young people.» In total, 48,161,019 Americans, or just over 22% of the population, had been immunized by the time the National Influenza Immunization Program was effectively halted on December 16, 1976.^[82]
[83]

Overall, there were 1098 cases of GBS recorded nationwide by CDC surveillance, 532 of which occurred after vaccination and 543 before vaccination.^[84] About one to two cases per 100,000 people of GBS occur every year, whether or not people have been vaccinated.^[85] The vaccination program seems to have increased this normal risk of developing GBS by about to one extra case per 100,000 vaccinations.^[85]

Recompensation charges were filed for over 4,000 cases of severe vaccination damage, including 25 deaths, totaling US$3.5 billion, by 1979.^[86]
The CDC stated most studies on modern influenza vaccines have seen no link with GBS,^[85][87][88] Although one review gives an incidence of about one case per million vaccinations,^[89] a large study in China, reported in the New England Journal of Medicine, covering close to 100 million doses of H1N1 flu vaccine, found only 11 cases of GBS, which is lower than the normal rate of the disease in China: «The risk-benefit ratio, which is what vaccines and everything in medicine is about, is overwhelmingly in favor of vaccination.»^[90]

1988 U.S.[edit]

In September 1988, a swine flu virus killed one woman and infected others. A 32-year-old woman, Barbara Ann Wieners, was eight months pregnant when she and her husband, Ed, became ill after visiting the hog barn at a county fair in Walworth County, Wisconsin. Barbara died eight days later, after developing pneumonia.^[91] The only pathogen identified was an H1N1 strain of swine influenza virus.^[92] Doctors were able to induce labor and deliver a healthy daughter before she died. Her husband recovered from his symptoms.

Influenza-like illness (ILI) was reportedly widespread among the pigs exhibited at the fair. Of the 25 swine exhibitors aged 9 to 19 at the fair, 19 tested positive for antibodies to SIV, but no serious illnesses were seen. The virus was able to spread between people, since one to three health care personnel who had cared for the pregnant woman developed mild, influenza-like illnesses, and antibody tests suggested they had been infected with swine flu, but there was no community outbreak.^[93][94]

In 1998, swine flu was found in pigs in four U.S. states. Within a year, it had spread through pig populations across the United States. Scientists found this virus had originated in pigs as a recombinant form of flu strains from birds and humans. This outbreak confirmed that pigs can serve as a crucible where novel influenza viruses emerge as a result of the reassortment of genes from different strains.^[2][95] Genetic components of these 1998 triple-hybrid strains would later form six out of the eight viral gene segments in the 2009 flu outbreak.^{[96][97][98][99][100]}

2007 Philippines[edit]

On August 20, 2007, Department of Agriculture officers investigated the outbreak of swine flu in Nueva Ecija and central Luzon, Philippines. The mortality rate is less than 10% for swine flu, unless there are complications like hog cholera. On July 27, 2007, the Philippine National Meat Inspection Service (NMIS) raised a hog cholera «red alert» warning over Metro Manila and five regions of Luzon after the disease spread to backyard pig farms in Bulacan and Pampanga, even if they tested negative for the swine flu virus.^[101][102]

2009 Northern Ireland[edit]

Since November 2009, 14 deaths as a result of swine flu in Northern Ireland have been reported. The majority of the deceased were reported to have pre-existing health conditions which had lowered their immunity. This closely corresponds to the 19 patients who had died in the year prior due to swine flu, where 18 of the 19 were determined to have lowered immune systems. Because of this, many mothers who have just given birth are strongly encouraged to get a flu shot because their immune systems are vulnerable. Also, studies have shown that people between the ages of 15 and 44 have the highest rate of infection. Although most people now recover, having any conditions that lower one’s immune system increases the risk of having the flu become potentially lethal. In Northern Ireland now, approximately 56% of all people under 65 who are entitled to the vaccine have gotten the shot, and the outbreak is said to be under control.^[103]

2015 and 2019 India[edit]

Swine flu outbreaks were reported in India in late 2014 and early 2015. As of March 19, 2015 the disease has affected 31,151 people and claimed over 1,841 lives.^[104][105] The largest number of reported cases and deaths due to the disease occurred in the western part of India including states like Delhi, Madhya Pradesh, Rajasthan, and Gujarat Andhra Pradesh
Researchers of MIT have claimed that the swine flu has mutated in India to a more virulent version with changes in Hemagglutinin protein,^[106] contradicting earlier research by Indian researchers.^[107]

There was another outbreak in India in 2017. The states of Maharashtra and Gujarat were the worst affected.^[108] Gujarat high court has given Gujarat government instructions to control deaths by swine flu.^[109] 1,090 people died of swine flu in India in 2019 until August 31, 2019.^[110]

2015 Nepal[edit]

Swine flu outbreaks were reported in Nepal in the spring of 2015. Up to April 21, 2015, the disease had claimed 26 lives in the most severely affected district, Jajarkot in Northwest Nepal.^[111] Cases were also detected in the districts of Kathmandu, Morang, Kaski, and Chitwan.^[112] As of 22 April 2015 the Nepal Ministry of Health reported that 2,498 people had been treated in Jajarkot, of whom 552 were believed to have swine flu, and acknowledged that the government’s response had been inadequate.^[113] The Jajarkot outbreak had just been declared an emergency when the April 2015 Nepal earthquake struck on 25 April 2015, diverting all medical and emergency resources to quake-related rescue and recovery.^{[citation needed]}

2016 Pakistan[edit]

Seven cases of swine flu were reported in Punjab province of Pakistan, mainly in the city of Multan, in January 2017. Cases of swine flu were also reported in Lahore and Faisalabad.^[114]

2017 Maldives[edit]

As of March 16, 2017, over a hundred confirmed cases of swine flu and at least six deaths were reported in the Maldivian capital of Malé and some other islands. Makeshift flu clinics were opened in Malé.^[115] Schools in the capital were closed, prison visitations suspended, several events cancelled, and all non-essential travel to other islands outside the capital was advised against by the HPA. An influenza vaccination program focusing on pregnant women was initiated thereafter.^[116] An official visit by Saudi King Salman bin Abdulaziz Al Saud to the Maldives during his Asian tour was also cancelled last minute amidst fears over the outbreak of swine flu.

2020 G4 EA H1N1 publication[edit]

G4 EA H1N1, also known as the G4 swine flu virus (G4) is a swine influenza virus strain discovered in China.^[117] The virus is a variant genotype 4 (G4) Eurasian avian-like (EA) H1N1 virus that mainly affects pigs, but there is some evidence of it infecting people.^[117] A peer-reviewed paper from the Proceedings of the National Academy of Sciences (PNAS) stated that «G4 EA H1N1 viruses possess all the essential hallmarks of being highly adapted to infect humans … Controlling the prevailing G4 EA H1N1 viruses in pigs and close monitoring of swine working populations should be promptly implemented.»^[118]

Michael Ryan, executive director of the World Health Organization (WHO) Health Emergencies Program, stated in July 2020 that this strain of influenza virus was not new and had been under surveillance since 2011.^[119] Almost 30,000 swine had been monitored via nasal swabs between 2011 and 2018.^[118] While other variants of the virus have appeared and diminished, the study claimed the G4 variant has sharply increased since 2016 to become the predominant strain.^[118][120] The Chinese Ministry of Agriculture and Rural Affairs rebutted the study, saying that the media had interpreted the study «in an exaggerated and nonfactual way» and that the number of pigs sampled was too small to demonstrate G4 had become the dominant strain.^[121]

Between 2016 and 2018, a serum surveillance program screened 338 swine production workers in China for exposure (presence of antibodies) to G4 EA H1N1 and found 35 (10.4%) positive.^[118] Among another 230 people screened who did not work in the swine industry, 10 (4.4%) were serum positive for antibodies indicating exposure.^[117][118] Two cases of infection caused by the G4 variant have been documented as of July 2020, with no confirmed cases of human-to-human transmission.^[117]

Health officials (including Anthony Fauci) say the virus should be monitored, particularly among those in close contact with pigs, but it is not an immediate threat.^[122][123] There are no reported cases or evidence of the virus outside of China as of July 2020.^[123]

H1N1 virus pandemic history[edit]

A 2008 study discussed the evolutionary origin of the flu strain of swine origin (S-OIV).^[124]

According to this study, the phylogenetic origin of the flu virus that caused the 2009 pandemics can be traced before 1918. Around 1918, the ancestral virus, of avian origin, crossed the species boundaries and infected humans as human H1N1. The same phenomenon took place soon after in America, where the human virus infected pigs; it led to the emergence of the H1N1 swine strain, which later became known as swine flu. Genetic coding of H1N1 shows it is a combination of segments of four influenza viruses forming a novel strain:

• North American Swine (30.6%) – pig origin
• North American Avian (34.4%) – bird origin
• Human influenza strain (17.5%)
• Eurasian swine (17.5%) – Pig origin

Quadruple genetic re-assortment – coinfection with influenza viruses from diverse animal species.

Due to coinfection, the viruses are able to interact, mutate, and form a new strain to which host has variable immunity.

New events of reassortment were not reported until 1968, when the avian strain H1N1 infected humans again; this time the virus met the strain H2N2, and the reassortment originated the strain H3N2. This strain has remained as a stable flu strain until now.

The mid-1970s were important for the evolution of flu strains. First, the re-emergence of the human H1N1 strain became a seasonal strain. Then, a small outbreak of swine H1N1 occurred in humans, and finally, the human H2N2 strain apparently became extinct. Around 1979, the avian H1N1 strain infected pigs and gave rise to Euroasiatic swine flu and H1N1 Euroasiatic swine virus, which is still being transmitted in swine populations.

The critical moment for the 2009 outbreak was between 1990 and 1993. A triple reassortment event in a pig host of North American H1N1 swine virus, the human H3N2 virus and avian H1N1 virus generated the swine H1N2 strain. In 2009, when the virus H1N2 co-infected a human host at the same time as the Euroasiatic H1N1 swine strain a new human H1N1 strain emerged, which caused the 2009 pandemic.

The swine flu spreads very rapidly worldwide due to its high human-to-human transmission rate and due to the frequency of air travel.^[125]

See also[edit]

• COVID-19 pandemic

Notes[edit]

Further reading[edit]

External links[edit]

• Official swine flu advice and latest information from the UK National Health Service
• 8 minute video answering common questions about the subject on fora.tv
• Swine flu charts and maps Numeric analysis and approximation of current active cases
• «Swine Influenza» disease card on World Organisation for Animal Health
• Worried about swine flu? Then you should be terrified about the regular flu.
• Centers for Disease Control and Prevention (CDC) – Swine Flu
• Center for Infectious Disease Research and Policy – Novel H1N1 influenza resource list
• Pandemic Flu US Government Site
• World Health Organization (WHO): Swine influenza
• Medical Encyclopedia Medline Plus: Swine Flu
• Health-EU portal EU response to influenza
• European Commission – Public Health EU coordination on Pandemic (H1N1) 2009

Swine influenza
Other names	Pig influenza, swine flu, hog flu, pig flu
Electron microscope image of the reassorted H1N1 influenza virus photographed at the CDC Influenza Laboratory. The viruses are 80–120 nanometres in diameter.[1]
Specialty	Infectious disease

Swine influenza is an infection caused by any of several types of swine influenza viruses. Swine influenza virus (SIV) or swine-origin influenza virus (S-OIV) refers to any strain of the influenza family of viruses that is endemic in pigs.^[2] As of 2009, identified SIV strains include influenza C and the subtypes of influenza A known as H1N1, H1N2, H2N1, H3N1, H3N2, and H2N3.^[3]

The swine influenza virus is common throughout pig populations worldwide. Transmission of the virus from pigs to humans is rare, and does not always lead to human illness, often resulting only in the production of antibodies in the blood. If transmission causes human human, it is called zoonotic swine flu. People with regular exposure to pigs are at increased risk of swine flu infections.

Around the mid-20th century, identification of influenza sub-types was made possible, allowing accurate diagnosis of transmission to humans. Since then, only 50 such transmissions have been confirmed. These strains of swine flu rarely pass from human to human. Symptoms of zoonotic swine flu in humans are similar to those of influenza and of influenza-like illness and include chills, fever, sore throat, muscle pains, severe headache, coughing, weakness, shortness of breath, and general discomfort.

It is estimated that, in the 2009 flu pandemic, 11–21% of the then global population (of about 6.8 billion), equivalent to around 700 million to 1.4 billion people, contracted the illness—more, in absolute terms, than the Spanish flu pandemic. There were 18,449 confirmed fatalities. However, in a 2012 study, the CDC estimated more than 284,000 possible fatalities worldwide, with numbers ranging from 150,000 to 575,000.^[4][5]
In August 2010, the World Health Organization declared the swine flu pandemic officially over.^[6][7]

Subsequent cases of swine flu were reported in India in 2015, with over 31,156 positive test cases and 1,841 deaths.

Signs and symptoms[edit]

In pigs, a swine influenza infection produces fever, lethargy, discharge from the nose or eyes, sneezing, coughing, difficulty breathing, eye redness or inflammation, and decreased appetite.^[8] In some cases the infection can cause miscarriage. However, it is possible that infected pigs may not exhibit any symptoms.^[9] Although mortality is usually low (around 1–4%),^[2] the virus can cause weight loss and poor growth, in turn causing economic loss to farmers.^[8] Infected pigs can lose up to 12 pounds of body weight over a three- to four-week period.^[8] Swine have receptors to which both avian and mammalian influenza viruses are able to bind; this leads to the virus being able to evolve and mutate into different forms.^[10] Influenza A is responsible for infecting swine, and was first identified in 1918.^[10] Pigs have often been seen as «mixing vessels», which help to change and evolve strains of disease that are then passed on to other mammals, such as humans.^[10]

Humans[edit]

Direct transmission of a swine flu virus from pigs to humans is occasionally possible (zoonotic swine flu).^[12] In all, 50 cases are known to have occurred since the first report in medical literature in 1958, which have resulted in a total of six deaths.^[13] Of these six people, one was pregnant, one had leukemia, one had Hodgkin’s lymphoma and two were known to be previously healthy. One of these had unknown whereabouts.^[13] Despite these apparently low numbers of infections, the true rate of infection may be higher, since most cases only cause a very mild disease, and will probably never be reported or diagnosed.^[13]

According to the United States Centers for Disease Control and Prevention (CDC), in humans the symptoms of the 2009 «swine flu» H1N1 virus are similar to influenza and influenza-like illness in general. Symptoms include fever, cough, sore throat, watery eyes, body aches, shortness of breath, headache, weight loss, chills, sneezing, runny nose, coughing, dizziness, abdominal pain, lack of appetite, and fatigue. The 2009 outbreak also had an increased percentage of patients reporting diarrhea and vomiting. The 2009 H1N1 virus is not zoonotic swine flu, as it is not transmitted from pigs to humans, but from person to person through airborne droplets.^[15]

Because these symptoms are not specific to swine flu, a differential diagnosis of probable swine flu requires not only symptoms, but also a high likelihood of swine flu due to the person’s recent and past medical history. For example, during the 2009 swine flu outbreak in the United States, the CDC advised physicians to «consider swine influenza infection in the differential diagnosis of patients with acute febrile respiratory illness who have either been in contact with persons with confirmed swine flu, or who were in one of the five U.S. states that have reported swine flu cases or in Mexico during the seven days preceding their illness onset.»^[16] A diagnosis of confirmed swine flu requires laboratory testing of a respiratory sample (a simple nose and throat swab).^[16]

The most common cause of death is respiratory failure. Other causes of death are pneumonia (leading to sepsis),^[17] high fever (leading to neurological problems), dehydration (from excessive vomiting and diarrhea), electrolyte imbalance and kidney failure.^[18] Fatalities are more likely in young children and the elderly.^{[citation needed]}

Virology[edit]

Transmission[edit]

Between pigs[edit]

Influenza is quite common in pigs, with about half of breeding pigs having been exposed to the virus in the US.^[19] Antibodies to the virus are also common in pigs in other countries.^[19]

The main route of transmission is through direct contact between infected and uninfected animals.^[8] These close contacts are particularly common during animal transport. Intensive farming may also increase the risk of transmission, as the pigs are raised in very close proximity to each other.^[20][21] The direct transfer of the virus probably occurs either by pigs touching noses, or through dried mucus. Airborne transmission through the aerosols produced by pigs coughing or sneezing are also an important means of infection.^[8] The virus usually spreads quickly through a herd, infecting all the pigs within just a few days.^[2] Transmission may also occur through wild animals, such as wild boar, which can spread the disease between farms.^[22]

To humans[edit]

People who work with poultry and swine, especially those with intense exposures, are at increased risk of zoonotic infection with influenza virus endemic in these animals, and constitute a population of human hosts in which zoonosis and reassortment can co-occur.^[23] Vaccination of these workers against influenza and surveillance for new influenza strains among this population may therefore be an important public health measure.^[24] Transmission of influenza from swine to humans who work with swine was documented in a small surveillance study performed in 2004 at the University of Iowa.^[25] This study, among others, forms the basis of a recommendation that people whose jobs involve handling poultry and swine be the focus of increased public health surveillance.^[23] Other professions at particular risk of infection are veterinarians and meat processing workers, although the risk of infection for both of these groups is lower than that of farm workers.^[26]

Interaction with avian H5N1 in pigs[edit]

Pigs are unusual as they can be infected with influenza strains that usually infect three different species: pigs, birds, and humans.^[27] Pigs are a host where influenza viruses might exchange genes, producing new and dangerous strains.^[27] Avian influenza virus H3N2 is endemic in pigs in China and has been detected in pigs in Vietnam, increasing fears of the emergence of new variant strains.^[28] H3N2 evolved from H2N2 by antigenic shift.^[29] In August 2004, researchers in China found H5N1 in pigs.^[30]

These H5N1 infections may be quite common; in a survey of 10 apparently healthy pigs housed near poultry farms in West Java, where avian flu had broken out, five of the pig samples contained the H5N1 virus. The Indonesian government has since found similar results in the same region. Additional tests of 150 pigs outside the area were negative.^[31][32]

Structure[edit]

The influenza virion is roughly spherical. It is an enveloped virus; the outer layer is a lipid membrane which is taken from the host cell in which the virus multiplies. Inserted into the lipid membrane are «spikes», which are proteins—actually glycoproteins, because they consist of protein linked to sugars—known as HA (hemagglutinin) and NA (neuraminidase). These are the proteins that determine the subtype of influenza virus (A/H1N1, for example). The HA and NA are important in the immune response against the virus; antibodies (proteins made to combat infection) against these spikes may protect against infection. The NA protein is the target of the antiviral drugs Relenza and Tamiflu. Also embedded in the lipid membrane is the M2 protein, which is the target of the antiviral adamantanes amantadine and rimantadine.^{[citation needed]}

Classification[edit]

Of the three genera of influenza viruses that cause human flu, two also cause influenza in pigs, with influenza A being common in pigs and influenza C being rare.^[33] Influenza B has not been reported in pigs. Within influenza A and influenza C, the strains found in pigs and humans are largely distinct, although because of reassortment there have been transfers of genes among strains crossing swine, avian, and human species boundaries.^{[citation needed]}

Influenza C[edit]

Influenza viruses infect both humans and pigs, but do not infect birds.^[34] Transmission between pigs and humans have occurred in the past.^[35] For example, influenza C caused small outbreaks of a mild form of influenza amongst children in Japan^[36] and California.^[36] Because of its limited host range and the lack of genetic diversity in influenza C, this form of influenza does not cause pandemics in humans.^[37]

Influenza A[edit]

Swine influenza is caused by influenza A subtypes H1N1,^[38] H1N2,^[38] H2N3,^[39] H3N1,^[40] and H3N2.^[38] In pigs, four influenza A virus subtypes (H1N1, H1N2, H3N2 and H7N9) are the most common strains worldwide.^[8] In the United States, the H1N1 subtype was exclusively prevalent among swine populations before 1998; however, since late August 1998, H3N2 subtypes have been isolated from pigs. As of 2004, H3N2 virus isolates in US swine and turkey stocks were triple reassortants, containing genes from human (HA, NA, and PB1), swine (NS, NP, and M), and avian (PB2 and PA) lineages.^[41] In August 2012, the Center for Disease Control and Prevention confirmed 145 human cases (113 in Indiana, 30 in Ohio, one in Hawaii and one in Illinois) of H3N2v since July 2012.^[42] The death of a 61-year-old Madison County, Ohio woman is the first in the USA associated with a new swine flu strain. She contracted the illness after having contact with hogs at the Ross County Fair.^[43]

Diagnosis[edit]

The CDC recommends real-time PCR as the method of choice for diagnosing H1N1.^[44] The oral or nasal fluid collection and RNA virus-preserving filter-paper card is commercially available.^[45] This method allows a specific diagnosis of novel influenza (H1N1) as opposed to seasonal influenza. Near-patient point-of-care tests are in development.^[46]

Prevention[edit]

Prevention of swine influenza has three components: prevention in pigs, prevention of transmission to humans, and prevention of its spread among humans. Proper handwashing techniques can prevent the virus from spreading. Avoid touching the eyes, nose, or mouth. Stay away from others who display symptoms of the cold or flu and avoid contact with others when displaying symptoms.^{[citation needed]}

Swine[edit]

Methods of preventing the spread of influenza among swine include facility management, herd management, and vaccination (ATCvet code: QI09AA03 (WHO)). Because much of the illness and death associated with swine flu involves secondary infection by other pathogens, control strategies that rely on vaccination may be insufficient.^{[citation needed]}

Control of swine influenza by vaccination has become more difficult in recent decades, as the evolution of the virus has resulted in inconsistent responses to traditional vaccines. Standard commercial swine flu vaccines are effective in controlling the infection when the virus strains match enough to have significant cross-protection, and custom (autogenous) vaccines made from the specific viruses isolated are created and used in the more difficult cases.^[47][48]
Present vaccination strategies for SIV control and prevention in swine farms typically include the use of one of several bivalent SIV vaccines commercially available in the United States. Of the 97 recent H3N2 isolates examined, only 41 isolates had strong serologic cross-reactions with antiserum to three commercial SIV vaccines. Since the protective ability of influenza vaccines depends primarily on the closeness of the match between the vaccine virus and the epidemic virus, the presence of nonreactive H3N2 SIV variants suggests current commercial vaccines might not effectively protect pigs from infection with a majority of H3N2 viruses.^[13][49] The United States Department of Agriculture researchers say while pig vaccination keeps pigs from getting sick, it does not block infection or shedding of the virus.^[50]

Facility management includes using disinfectants and ambient temperature to control viruses in the environment. They are unlikely to survive outside living cells for more than two weeks, except in cold (but above freezing) conditions, and are readily inactivated by disinfectants.^[2] Herd management includes not adding pigs carrying influenza to herds that have not been exposed to the virus. The virus survives in healthy carrier pigs for up to three months and can be recovered from them between outbreaks. Carrier pigs are usually responsible for the introduction of SIV into previously uninfected herds and countries, so new animals should be quarantined.^[19] After an outbreak, as immunity in exposed pigs wanes, new outbreaks of the same strain can occur.^[2]

Humans[edit]

Prevention of pig-to-human transmission

Swine can be infected by both avian and human flu strains of influenza, and therefore are hosts where the antigenic shifts can occur that create new influenza strains.^{[citation needed]}

The transmission from swine to humans is believed to occur mainly in swine farms, where farmers are in close contact with live pigs. Although strains of swine influenza are usually not able to infect humans, it may occasionally happen, so farmers and veterinarians are encouraged to use face masks when dealing with infected animals. The use of vaccines on swine to prevent their infection is a major method of limiting swine-to-human transmission. Risk factors that may contribute to the swine-to-human transmission include smoking and, especially, not wearing gloves when working with sick animals, thereby increasing the likelihood of subsequent hand-to-eye, hand-to-nose, or hand-to-mouth transmission.^[51]

Prevention of human-to-human transmission

Influenza spreads between humans when infected people cough or sneeze, then other people breathe in the virus or touch something with the virus on it and then touch their own face.^[52] «Avoid touching your eyes, nose or mouth. Germs spread this way.»^[53] Swine flu cannot be spread by pork products, since the virus is not transmitted through food.^[52] The swine flu in humans is most contagious during the first five days of the illness, although some people, most commonly children, can remain contagious for up to ten days. Diagnosis can be made by sending a specimen, collected during the first five days, for analysis.^[54]

Recommendations to prevent the spread of the virus among humans include using standard infection control, which includes frequent washing of hands with soap and water or with alcohol-based hand sanitizers, especially after being out in public.^[55] Chance of transmission is also reduced by disinfecting household surfaces, which can be done effectively with a diluted chlorine bleach solution.^[56]

Experts agree hand-washing can help prevent viral infections, including ordinary and swine flu infections. Also, avoiding touching one’s eyes, nose, or mouth with one’s hands helps to prevent the flu.^[53] Influenza can spread in coughs or sneezes, but an increasing body of evidence shows small droplets containing the virus can linger on tabletops, telephones, and other surfaces and be transferred via the fingers to the eyes, nose, or mouth. Alcohol-based gel or foam hand sanitizers work well to destroy viruses and bacteria. Anyone with flu-like symptoms, such as a sudden fever, cough, or muscle aches, should stay away from work or public transportation and should contact a doctor for advice.^[57]

Social distancing, another tactic, is staying away from other people who might be infected, and can include avoiding large gatherings, spreading out a little at work, or perhaps staying home and lying low if an infection is spreading in a community. Public health and other responsible authorities have action plans which may request or require social distancing actions, depending on the severity of the outbreak.^{[citation needed]}

Vaccination[edit]

Vaccines are available for different kinds of swine flu. The U.S. Food and Drug Administration (FDA) approved the new swine flu vaccine for use in the United States on September 15, 2009.^[58] Studies by the National Institutes of Health show a single dose creates enough antibodies to protect against the virus within about 10 days.^[59]

In the aftermath of the 2009 pandemic, several studies were conducted to see who received influenza vaccines. These studies show that whites are much more likely to be vaccinated for seasonal influenza and for the H1N1 strain than African Americans ^[60] This could be due to several factors. Historically, there has been mistrust of vaccines and of the medical community from African Americans. Many African Americans do not believe vaccines or doctors to be effective. This mistrust stems from the exploitation of the African American communities during studies like the Tuskegee study. Additionally, vaccines are typically administered in clinics, hospitals, or doctor’s offices. Many people of lower socioeconomic status are less likely to receive vaccinations because they do not have health insurance.^{[citation needed]}

Surveillance[edit]

Although there is no formal national surveillance system in the United States to determine what viruses are circulating in pigs,^[61] an informal surveillance network in the United States is part of a world surveillance network.^[62]

Treatment[edit]

Swine[edit]

As swine influenza is rarely fatal to pigs, little treatment beyond rest and supportive care is required.^[19] Instead, veterinary efforts are focused on preventing the spread of the virus throughout the farm or to other farms.^[8] Vaccination and animal management techniques are most important in these efforts. Antibiotics are also used to treat the disease, which, although they have no effect against the influenza virus, do help prevent bacterial pneumonia and other secondary infections in influenza-weakened herds.^[19]

In Europe the avian-like H1N1 and the human-like H3N2 and H1N2 are the most common influenza subtypes in swine, of which avian-like H1N1 is the most frequent. Since 2009 another subtype, pdmH1N1(2009), emerged globally and also in European pig population. The prevalence varies from country to country but all of the subtypes are continuously circulating in swine herds.^[63]
In the EU region whole-virus vaccines are available which are inactivated and adjuvanted. Vaccination of sows is common practice and reveals also a benefit to young pigs by prolonging the maternally level of antibodies. Several commercial vaccines are available including a trivalent one being used in sow vaccination and a vaccine against pdmH1N1(2009).^[64] In vaccinated sows multiplication of viruses and virus shedding are significantly reduced.^{[citation needed]}

Humans[edit]

If a human becomes sick with swine flu, antiviral drugs can make the illness milder and make the patient feel better faster. They may also prevent serious flu complications. For treatment, antiviral drugs work best if started soon after getting sick (within two days of symptoms). Beside antivirals, supportive care at home or in a hospital focuses on controlling fevers, relieving pain and maintaining fluid balance, as well as identifying and treating any secondary infections or other medical problems. The U.S. Centers for Disease Control and Prevention recommends the use of oseltamivir (Tamiflu) or zanamivir (Relenza) for the treatment and/or prevention of infection with swine influenza viruses; however, the majority of people infected with the virus make a full recovery without requiring medical attention or antiviral drugs.^[65] The virus isolated in the 2009 outbreak have been found resistant to amantadine and rimantadine.^[66]

History[edit]

Pandemics[edit]

Swine influenza was first proposed to be a disease related to human flu during the 1918 flu pandemic, when pigs became ill at the same time as humans.^[67] The first identification of an influenza virus as a cause of disease in pigs occurred about ten years later, in 1930.^[68] For the following 60 years, swine influenza strains were almost exclusively H1N1. Then, between 1997 and 2002, new strains of three different subtypes and five different genotypes emerged as causes of influenza among pigs in North America. In 1997–1998, H3N2 strains emerged. These strains, which include genes derived by reassortment from human, swine and avian viruses, have become a major cause of swine influenza in North America. Reassortment between H1N1 and H3N2 produced H1N2. In 1999 in Canada, a strain of H4N6 crossed the species barrier from birds to pigs, but was contained on a single farm.^[68]

The H1N1 form of swine flu is one of the descendants of the strain that caused the 1918 flu pandemic.^[69][70] As well as persisting in pigs, the descendants of the 1918 virus have also circulated in humans through the 20th century, contributing to the normal seasonal epidemics of influenza.^[70] However, direct transmission from pigs to humans is rare, with only 12 recorded cases in the U.S. since 2005.^[71] Nevertheless, the retention of influenza strains in pigs after these strains have disappeared from the human population might make pigs a reservoir where influenza viruses could persist, later emerging to reinfect humans once human immunity to these strains has waned.^[72]

Swine flu has been reported numerous times as a zoonosis in humans, usually with limited distribution, rarely with a widespread distribution. Outbreaks in swine are common and cause significant economic losses in industry, primarily by causing stunting and extended time to market. For example, this disease costs the British meat industry about £65 million every year.^[73]

1918[edit]

The 1918 flu pandemic in humans was associated with H1N1 and influenza appearing in pigs;^[70] this may reflect a zoonosis either from swine to humans, or from humans to swine. Although it is not certain in which direction the virus was transferred, some evidence suggests, in this case, pigs caught the disease from humans.^[67] For instance, swine influenza was only noted as a new disease of pigs in 1918, after the first large outbreaks of influenza amongst people.^[67] Although a recent phylogenetic analysis of more recent strains of influenza in humans, birds, animals, and many others, including swine, suggests the 1918 outbreak in humans followed a reassortment event within a mammal,^[74] the exact origin of the 1918 strain remains elusive.^[75] It is estimated that anywhere from 50 to 100 million people were killed worldwide.^[70][76]

U.S. 2009[edit]

The swine flu was initially seen in the US in April 2009, where the strain of the particular virus was a mixture from 3 types of strains.^[77] Six of the genes are very similar to the H1N2 influenza virus that was found in pigs around 2000.^[77]

Outbreaks[edit]

1976 U.S.[edit]

On February 5, 1976, a United States army recruit at Fort Dix said he felt tired and weak. He died the next day, and four of his fellow soldiers were later hospitalized. Two weeks after his death, health officials announced the cause of death was a new strain of swine flu. The strain, a variant of H1N1, is known as A/New Jersey/1976 (H1N1). It was detected only from January 19 to February 9 and did not spread beyond Fort Dix.^[78]

This new strain appeared to be closely related to the strain involved in the 1918 flu pandemic. Moreover, the ensuing increased surveillance uncovered another strain in circulation in the U.S.: A/Victoria/75 (H3N2), which spread simultaneously, also caused illness, and persisted until March.^[78] Alarmed public health officials decided action must be taken to head off another major pandemic, and urged President Gerald Ford that every person in the U.S. be vaccinated for the disease.^[79]

The vaccination program was plagued by delays and public relations problems.^[80] On October 1, 1976, immunizations began, and three senior citizens died soon after receiving their injections. This resulted in a media outcry that linked these deaths to the immunizations, despite the lack of any proof the vaccine was the cause. According to science writer Patrick Di Justo, however, by the time the truth was known—that the deaths were not proven to be related to the vaccine—it was too late. «The government had long feared mass panic about swine flu—now they feared mass panic about the swine flu vaccinations.» This became a strong setback to the program.^[81]

There were reports of Guillain–Barré syndrome (GBS), a paralyzing neuromuscular disorder, affecting some people who had received swine flu immunizations. Although whether a link exists is still not clear, this syndrome may be a side effect of influenza vaccines. As a result, Di Justo writes, «the public refused to trust a government-operated health program that killed old people and crippled young people.» In total, 48,161,019 Americans, or just over 22% of the population, had been immunized by the time the National Influenza Immunization Program was effectively halted on December 16, 1976.^[82]
[83]

Overall, there were 1098 cases of GBS recorded nationwide by CDC surveillance, 532 of which occurred after vaccination and 543 before vaccination.^[84] About one to two cases per 100,000 people of GBS occur every year, whether or not people have been vaccinated.^[85] The vaccination program seems to have increased this normal risk of developing GBS by about to one extra case per 100,000 vaccinations.^[85]

Recompensation charges were filed for over 4,000 cases of severe vaccination damage, including 25 deaths, totaling US$3.5 billion, by 1979.^[86]
The CDC stated most studies on modern influenza vaccines have seen no link with GBS,^[85][87][88] Although one review gives an incidence of about one case per million vaccinations,^[89] a large study in China, reported in the New England Journal of Medicine, covering close to 100 million doses of H1N1 flu vaccine, found only 11 cases of GBS, which is lower than the normal rate of the disease in China: «The risk-benefit ratio, which is what vaccines and everything in medicine is about, is overwhelmingly in favor of vaccination.»^[90]

1988 U.S.[edit]

In September 1988, a swine flu virus killed one woman and infected others. A 32-year-old woman, Barbara Ann Wieners, was eight months pregnant when she and her husband, Ed, became ill after visiting the hog barn at a county fair in Walworth County, Wisconsin. Barbara died eight days later, after developing pneumonia.^[91] The only pathogen identified was an H1N1 strain of swine influenza virus.^[92] Doctors were able to induce labor and deliver a healthy daughter before she died. Her husband recovered from his symptoms.

Influenza-like illness (ILI) was reportedly widespread among the pigs exhibited at the fair. Of the 25 swine exhibitors aged 9 to 19 at the fair, 19 tested positive for antibodies to SIV, but no serious illnesses were seen. The virus was able to spread between people, since one to three health care personnel who had cared for the pregnant woman developed mild, influenza-like illnesses, and antibody tests suggested they had been infected with swine flu, but there was no community outbreak.^[93][94]

In 1998, swine flu was found in pigs in four U.S. states. Within a year, it had spread through pig populations across the United States. Scientists found this virus had originated in pigs as a recombinant form of flu strains from birds and humans. This outbreak confirmed that pigs can serve as a crucible where novel influenza viruses emerge as a result of the reassortment of genes from different strains.^[2][95] Genetic components of these 1998 triple-hybrid strains would later form six out of the eight viral gene segments in the 2009 flu outbreak.^{[96][97][98][99][100]}

2007 Philippines[edit]

On August 20, 2007, Department of Agriculture officers investigated the outbreak of swine flu in Nueva Ecija and central Luzon, Philippines. The mortality rate is less than 10% for swine flu, unless there are complications like hog cholera. On July 27, 2007, the Philippine National Meat Inspection Service (NMIS) raised a hog cholera «red alert» warning over Metro Manila and five regions of Luzon after the disease spread to backyard pig farms in Bulacan and Pampanga, even if they tested negative for the swine flu virus.^[101][102]

2009 Northern Ireland[edit]

Since November 2009, 14 deaths as a result of swine flu in Northern Ireland have been reported. The majority of the deceased were reported to have pre-existing health conditions which had lowered their immunity. This closely corresponds to the 19 patients who had died in the year prior due to swine flu, where 18 of the 19 were determined to have lowered immune systems. Because of this, many mothers who have just given birth are strongly encouraged to get a flu shot because their immune systems are vulnerable. Also, studies have shown that people between the ages of 15 and 44 have the highest rate of infection. Although most people now recover, having any conditions that lower one’s immune system increases the risk of having the flu become potentially lethal. In Northern Ireland now, approximately 56% of all people under 65 who are entitled to the vaccine have gotten the shot, and the outbreak is said to be under control.^[103]

2015 and 2019 India[edit]

Swine flu outbreaks were reported in India in late 2014 and early 2015. As of March 19, 2015 the disease has affected 31,151 people and claimed over 1,841 lives.^[104][105] The largest number of reported cases and deaths due to the disease occurred in the western part of India including states like Delhi, Madhya Pradesh, Rajasthan, and Gujarat Andhra Pradesh
Researchers of MIT have claimed that the swine flu has mutated in India to a more virulent version with changes in Hemagglutinin protein,^[106] contradicting earlier research by Indian researchers.^[107]

There was another outbreak in India in 2017. The states of Maharashtra and Gujarat were the worst affected.^[108] Gujarat high court has given Gujarat government instructions to control deaths by swine flu.^[109] 1,090 people died of swine flu in India in 2019 until August 31, 2019.^[110]

2015 Nepal[edit]

Swine flu outbreaks were reported in Nepal in the spring of 2015. Up to April 21, 2015, the disease had claimed 26 lives in the most severely affected district, Jajarkot in Northwest Nepal.^[111] Cases were also detected in the districts of Kathmandu, Morang, Kaski, and Chitwan.^[112] As of 22 April 2015 the Nepal Ministry of Health reported that 2,498 people had been treated in Jajarkot, of whom 552 were believed to have swine flu, and acknowledged that the government’s response had been inadequate.^[113] The Jajarkot outbreak had just been declared an emergency when the April 2015 Nepal earthquake struck on 25 April 2015, diverting all medical and emergency resources to quake-related rescue and recovery.^{[citation needed]}

2016 Pakistan[edit]

Seven cases of swine flu were reported in Punjab province of Pakistan, mainly in the city of Multan, in January 2017. Cases of swine flu were also reported in Lahore and Faisalabad.^[114]

2017 Maldives[edit]

As of March 16, 2017, over a hundred confirmed cases of swine flu and at least six deaths were reported in the Maldivian capital of Malé and some other islands. Makeshift flu clinics were opened in Malé.^[115] Schools in the capital were closed, prison visitations suspended, several events cancelled, and all non-essential travel to other islands outside the capital was advised against by the HPA. An influenza vaccination program focusing on pregnant women was initiated thereafter.^[116] An official visit by Saudi King Salman bin Abdulaziz Al Saud to the Maldives during his Asian tour was also cancelled last minute amidst fears over the outbreak of swine flu.

2020 G4 EA H1N1 publication[edit]

G4 EA H1N1, also known as the G4 swine flu virus (G4) is a swine influenza virus strain discovered in China.^[117] The virus is a variant genotype 4 (G4) Eurasian avian-like (EA) H1N1 virus that mainly affects pigs, but there is some evidence of it infecting people.^[117] A peer-reviewed paper from the Proceedings of the National Academy of Sciences (PNAS) stated that «G4 EA H1N1 viruses possess all the essential hallmarks of being highly adapted to infect humans … Controlling the prevailing G4 EA H1N1 viruses in pigs and close monitoring of swine working populations should be promptly implemented.»^[118]

Michael Ryan, executive director of the World Health Organization (WHO) Health Emergencies Program, stated in July 2020 that this strain of influenza virus was not new and had been under surveillance since 2011.^[119] Almost 30,000 swine had been monitored via nasal swabs between 2011 and 2018.^[118] While other variants of the virus have appeared and diminished, the study claimed the G4 variant has sharply increased since 2016 to become the predominant strain.^[118][120] The Chinese Ministry of Agriculture and Rural Affairs rebutted the study, saying that the media had interpreted the study «in an exaggerated and nonfactual way» and that the number of pigs sampled was too small to demonstrate G4 had become the dominant strain.^[121]

Between 2016 and 2018, a serum surveillance program screened 338 swine production workers in China for exposure (presence of antibodies) to G4 EA H1N1 and found 35 (10.4%) positive.^[118] Among another 230 people screened who did not work in the swine industry, 10 (4.4%) were serum positive for antibodies indicating exposure.^[117][118] Two cases of infection caused by the G4 variant have been documented as of July 2020, with no confirmed cases of human-to-human transmission.^[117]

Health officials (including Anthony Fauci) say the virus should be monitored, particularly among those in close contact with pigs, but it is not an immediate threat.^[122][123] There are no reported cases or evidence of the virus outside of China as of July 2020.^[123]

H1N1 virus pandemic history[edit]

A 2008 study discussed the evolutionary origin of the flu strain of swine origin (S-OIV).^[124]

According to this study, the phylogenetic origin of the flu virus that caused the 2009 pandemics can be traced before 1918. Around 1918, the ancestral virus, of avian origin, crossed the species boundaries and infected humans as human H1N1. The same phenomenon took place soon after in America, where the human virus infected pigs; it led to the emergence of the H1N1 swine strain, which later became known as swine flu. Genetic coding of H1N1 shows it is a combination of segments of four influenza viruses forming a novel strain:

• North American Swine (30.6%) – pig origin
• North American Avian (34.4%) – bird origin
• Human influenza strain (17.5%)
• Eurasian swine (17.5%) – Pig origin

Quadruple genetic re-assortment – coinfection with influenza viruses from diverse animal species.

Due to coinfection, the viruses are able to interact, mutate, and form a new strain to which host has variable immunity.

New events of reassortment were not reported until 1968, when the avian strain H1N1 infected humans again; this time the virus met the strain H2N2, and the reassortment originated the strain H3N2. This strain has remained as a stable flu strain until now.

The mid-1970s were important for the evolution of flu strains. First, the re-emergence of the human H1N1 strain became a seasonal strain. Then, a small outbreak of swine H1N1 occurred in humans, and finally, the human H2N2 strain apparently became extinct. Around 1979, the avian H1N1 strain infected pigs and gave rise to Euroasiatic swine flu and H1N1 Euroasiatic swine virus, which is still being transmitted in swine populations.

The critical moment for the 2009 outbreak was between 1990 and 1993. A triple reassortment event in a pig host of North American H1N1 swine virus, the human H3N2 virus and avian H1N1 virus generated the swine H1N2 strain. In 2009, when the virus H1N2 co-infected a human host at the same time as the Euroasiatic H1N1 swine strain a new human H1N1 strain emerged, which caused the 2009 pandemic.

The swine flu spreads very rapidly worldwide due to its high human-to-human transmission rate and due to the frequency of air travel.^[125]

See also[edit]

• COVID-19 pandemic

Notes[edit]

Further reading[edit]

External links[edit]

• Official swine flu advice and latest information from the UK National Health Service
• 8 minute video answering common questions about the subject on fora.tv
• Swine flu charts and maps Numeric analysis and approximation of current active cases
• «Swine Influenza» disease card on World Organisation for Animal Health
• Worried about swine flu? Then you should be terrified about the regular flu.
• Centers for Disease Control and Prevention (CDC) – Swine Flu
• Center for Infectious Disease Research and Policy – Novel H1N1 influenza resource list
• Pandemic Flu US Government Site
• World Health Organization (WHO): Swine influenza
• Medical Encyclopedia Medline Plus: Swine Flu
• Health-EU portal EU response to influenza
• European Commission – Public Health EU coordination on Pandemic (H1N1) 2009

Свиной грипп (англ. Swine influenza) — условное название заболевания людей и животных, вызываемого штаммами вируса гриппа. Название широко распространялось в СМИ в начале 2009 года. Штаммы, ассоциированные со вспышками т. н. «свиного гриппа», обнаружены среди вирусов гриппа серотипа C и подтипов серотипа А (А/H1N1, А/H1N2, А/H3N1, А/H3N2 и А/H2N3). Эти штаммы известны под общим названием «вирус свиного гриппа». Свиной грипп распространён среди домашних свиней в США, Мексике, Канаде, Южной Америке, Европе, Кении, материковом Китае, Тайване, Японии и других странах Азии.^[2] При этом вирус может циркулировать в среде людей, птиц и др. видов; этот процесс сопровождается его мутациями.^[3]

Эпидемиология

Передача вируса от животного к человеку мало распространена, и правильно приготовленная (термически обработанная) свинина не может быть источником заражения. Передаваясь от животного к человеку, вирус не всегда вызывает заболевание и часто выявляется только по наличию антител в крови человека. Случаи, когда передача вируса от животного к человеку приводит к заболеванию, называют зоонозным свиным гриппом. Люди, работающие со свиньями, подвергаются риску заражения этим заболеванием, тем не менее с середины двадцатых годов XX века (когда впервые стала возможной идентификация подтипов вируса гриппа) было зарегистрировано всего лишь около 50 таких случаев. Некоторые из штаммов, вызвавших заболевание у людей, приобрели способность передаваться от человека к человеку. Свиной грипп вызывает у человека симптомы, типичные для гриппа и ОРВИ. Вирус свиного гриппа передается как через непосредственный контакт с заражёнными организмами, так и воздушно-капельным путем (см. Механизм передачи возбудителя инфекции).

Этиология

Основная статья: H1N1

Вспышка нового штамма вируса гриппа в 2009 году, получившая известность как «свиной грипп», была вызвана вирусом подтипа H1N1, обладающим наибольшим генетическим сходством с вирусом свиного гриппа. Происхождение этого штамма точно не известно. Тем не менее Всемирная организация по охране здоровья животных (World Organization for Animal Health) сообщает, что эпидемическое распространение вируса этого же штамма не удалось установить среди свиней. ^[4] Вирусы этого штамма передаются от человека к человеку ^[5] и вызывают заболевания с симптомами, обычными для гриппа. ^[6]

Свиньи могут быть инфицированы вирусом гриппа человека, и именно это могло произойти как во время пандемии Испанского гриппа, так и вспышки 2009 года.

Патогенез

В целом механизм воздействия данного вируса аналогичен таковому при поражении другими штаммами вируса гриппа. Входными воротами инфекции является эпителий слизистых оболочек дыхательных путей человека, где происходит его репликация и репродукция. Наблюдается поверхностное поражение клеток трахеи и бронхов, характеризующееся процессами дегенерации, некроза и отторжения поражённых клеток.

Развитие патологического процесса сопровождается вирусемией, длящейся 10 −14 дней, с преобладанием токсических и токсико-аллергических реакций со стороны внутренних органов, в первую очередь сердечно-сосудистой и нервной систем.

Главным звеном в патогенезе является поражение сосудистой системы, проявляющееся повышением проницаемости и ломкости сосудистой стенки, нарушением микроциркуляции. Данные изменения проявляются у больных появлением ринорагий (носовых кровотечений), геморрагий на коже и слизистых, кровоизлияниями во внутренние органы, а также приводят к развитию патологических изменений в лёгких: отёку легочной ткани с множественными кровоизлияниями в альвеолы и интерстиций.

Падение тонуса сосудов приводит к возникновению венозной гиперемии кожи и слизистых оболочек, застойному полнокровию внутренних органов, нарушению микроциркуляции, диапедезным кровоизлияниям, на более поздних сроках — тромбозам вен и капилляров.

Данные сосудистые изменения также вызывают гиперсекрецию ликвора с развитием циркуляторных расстройств, приводящих к внутричерепной гипертензии и отёку мозга^[7].

Клиника

Основные симптомы совпадают с обычными симптомами гриппа ^[8] — головная боль, повышение температуры, кашель, насморк. Также появляется диарея, рвота, боли в животе. Существенную роль в патогенезе играет поражение лёгких и бронхов вследствие усиления экспрессии ряда факторов — медиаторов воспаления (TLR-3, γ-IFN, TNFα и др.), что приводит к множественному повреждению альвеол, некрозу и геморрагии ^[9] Высокая вирулентность и патогенность этого штамма вируса может быть обусловлена способностью неструктурного белка NS1 (присущего этому вирусу) ингибировать продукцию интерферонов I типа инфицированными клетками^[10]. Дефектные по этому гену вирусы оказываются существенно менее патогенными ^[11].

Диагностика

Клинически течение данного заболевания в целом совпадает с течением заболевания при инфицировании другими штаммами вируса гриппа. Достоверный диагноз устанавливается при серотипировании вируса

Профилактика

В целях первичной специфической профилактики (прежде всего лиц категории риска) в РФ и за рубежом проводится ускоренная разработка и регистрация специфических вакцин на основе выделенного штамма возбудителя. Эпидемиологи приветствуют также вакцинацию от «сезонного» гриппа, содержащую антитела против повреждающих агентов (белков) трёх, отличающихся от «свиного» штамма видов вируса.

В памятке ВОЗ о высокопатогенном гриппе указывается на необходимость исключить близкий контакт с людьми, которые «кажутся нездоровыми, имеющие высокую температуру тела и кашель». Рекомендуется тщательно и достаточно часто мыть руки с мылом. «Придерживайтесь здорового образа жизни, включая полноценный сон, употребление здоровой пищи, физическую активность» ^[12]. При должной термообработке вирус погибает. Первичная неспецифическая профилактика направлена на предотвращение попадание вируса в организм и на усиление неспецифического иммунного ответа для предотвращения развития заболевания.

Лечение

Лечение заболевания, вызванного штаммами вируса «свиного» гриппа по сути не отличается от лечения так называемого «сезонного» гриппа. При выраженных явлениях интоксикации и нарушениях кислотно-щелочного баланса проводится дезинтоксикационная и корректирующая терапия. Из препаратов, действующих на сам вирус и на его размножение доказана эффективность Осельтамивира (Тами-Флю). При его отсутствии экспертами ВОЗ рекомендуется препарат Занамивир (Реленза)^[13], при относительно лёгком течении заболевания врачи стран постсоветского пространства рекомендуют арбидол, несмотря на то, что он относится к лекарственным средствам с недоказанной эффективностью, а ВОЗ вовсе не рассматривает его в качестве противовирусного препарата.

Лечение тяжелых и средней степени тяжести случаев направлено на недопущение первичной вирусной пневмонии, обычно протекающей тяжело и вызывающей геморрагии и выраженную дыхательную недостаточность, и на профилактику присоединения вторичной бактериальной инфекции, также часто обуславливающей развитие пневмонии.

Показана также симптоматическая терапия. Из жаропонижающих препаратов большинством специалистов рекомендуются препараты содержащие ибупрофен и парацетамол (не рекомендуется использовать средства, содержащие аспирин, в связи с риском развития синдрома Рея^[14]).

Срочное обращение в медицинские учреждения (вызов скорой помощи) необходимо при признаках выраженной дыхательной недостаточности, угнетения мозговой деятельности и нарушений функции сердечно-сосудистой системы: одышки, нехватке дыхания, цианозе (посинения кожи), обмороке, появлении окрашенной мокроты, низком кровяном давлении, появлении болей в груди.

Обязательное обращение к врачу (как правило в поликлинику по месту жительства) необходимо при высокой температуре, не снижающейся на 4-й день, выраженного ухудшения состояния после временного улучшения.

Рекомендации по профилактике и лечению гриппа Министерства здравоохранения и социального развития РФ

Министерство здравоохранения и социального развития РФ выпустило «Временные методические рекомендации по лечению и профилактике гриппа A/H1N1»^[15].

Временные методические рекомендации по схемам лечения и профилактики гриппа, вызванного вирусом типа А/H1N1, для взрослого и детского населения были подготовлены совместно с ведущими научно-исследовательскими институтами РАМН, это НИИ гриппа, НИИ эпидемиологии и микробиологии им. Н. Ф. Гамалеи и ФГУ «Научно-исследовательский институт детских инфекций» и НИИ пульмонологии ФМБА России. От международных рекомендаций они отличаются наличием в них указаний на использование препаратов с недоказанной клинической эффективностью.

Эпидемии, вызванные вирусом гриппа H1N1

Пандемия в 1918 г. — «Испанка»

Испанский грипп или «испанка» (фр. La Grippe Espagnole, или исп. La Pesadilla) был, вероятней всего, самой страшной пандемией гриппа за всю историю человечества. В 1918—1919 годах во всем мире от испанки умерло приблизительно 50-100 млн человек. Было заражено около 400 млн человек, или 21,5 % населения планеты. Эпидемия началась в последние месяцы Первой мировой войны и быстро затмила это крупнейшее кровопролитие по масштабу жертв.

Вспышка гриппа в 1976 году

Вспышка гриппа в 1988 году

Вспышка гриппа в 2007 году

20 августа 2007 года Департамент Сельского хозяйства Филиппин зарегистрировала вспышку гриппа H1N1 на свинофермах провинции Nueva Ecija и центрального Лусона.

Пандемия гриппа A/H1N1 2009

В апреле-мае 2009 года вспышка нового штамма вируса гриппа^[16] наблюдалась в Мексике и США. Всемирная организация здравоохранения (ВОЗ) и Центры по контролю и профилактике заболеваний США (CDC)^[17] выразили серьёзную обеспокоенность этим новым штаммом по причине того, что существует возможность его передачи от человека к человеку, имеется высокая смертность в Мексике, а также потому, что этот штамм может перерасти в пандемию гриппа. 29 апреля на экстренном заседании ВОЗ повысила уровень пандемической угрозы с 4 до 5 баллов (из 6 возможных) ^[18].

По состоянию на 27 августа 2009 года^[19] зарегистрировано около 255716 случаев инфицирования гриппом A/H1N1 и 2627 смертей в более чем 140 регионах мира.^[20] В целом заболевание этим гриппом протекает по классическому сценарию, частота осложнений и смертей (чаще вследствие пневмонии) не превышает средние показатели при сезонном гриппе.

На данный момент идут споры вокруг того, как же все-таки называть данный штамм гриппа. Так, 27 апреля 2009 г. «свиной грипп» назвали «Калифорния 04/2009» ^[21], 30 апреля производители свинины выступили за переименование «свиной грипп» в «мексиканский» ^[22]; четкого ненаучного наименования не придумано до сих пор.

Пятый уровень угрозы был объявлен в конце апреля 2009 года: в соответствии с принятой ВОЗ классификацией, этот уровень характеризуется распространением вируса от человека к человеку по меньшей мере в двух странах одного региона.

11 июня 2009 года ВОЗ объявила^[23] о пандемии свиного гриппа, первой пандемии за последние 40 лет. В этот же день ему была присвоена шестая степень угрозы (из шести). Степень угрозы во ВОЗ не характеризует патогенность вируса (то есть опасность заболевания для жизни людей), а указывает на его способность к распространению. Т.о., любой грипп, передающийся от человека к человеку, достигает шестой степени угрозы.

Тем не менее, опасения ВОЗ связаны с генетической новизной штамма Калифорния и его потенциальной способностью к дальнейшей реассортации, вследствие чего возможно возникновение более агрессивных вариантов инфекции. Тогда, по аналогии с наиболее разрушительными пандемиями прошлого века, этот вирус приведет к серьезным людским потерям спустя некоторый (обычно полугодовой) период, сопровождающийся относительно умеренной летальностью.

Грипп и общество: социально-экономические последствия

В Гонконге в связи с угрозой эпидемии свиного гриппа с 1 мая введен режим чрезвычайной ситуации. Гостиница, где остановилась заболевшая туристка, блокирована и оцеплена полицией^[24]

Профилактические мероприятия усилили социальную напряженность и вылились в Египте в небольшой крестьянский бунт, когда 3 мая 300—400 «нехороших» свиноводов собрались на улицах Каирa, чтобы спасти от угрозы уничтожения своих кормильцев. Демонстранты бросали в полицейских камни и бутылки, поэтому спецподразделения полиции по борьбе с уличными беспорядками были вынуждены применить резиновые дубинки и слезоточивый газ, чтобы разогнать протестующих^[25].

Президент США Барак Обама 24 октября 2009 года объявил чрезвычайное положение в связи с гриппом А/H1N1^[26]. Как сообщают представители Белого дома, Обама подписал соответствующий акт, в котором говорится, что грипп А/H1N1 является национальной угрозой для США.

Прогноз течения болезни и показатели смертности

Прогноз течения заболевания условно благоприятный, при адекватном иммунном статусе и у лиц не входящих в группы риска время заболевания не превышает 2 недель и заканчивается полным выздоровлением. Трудоспособность полностью восстанавливается.

При сниженном иммунитете, а также у лиц, входящих в группы риска, возможно развитие тяжелых, опасных для жизни осложнений.

Следует отметить, что смертность при инфицировании данным вирусом не превышает смертность при поражении другими штаммами вируса.^[27][28][29] Согласно данным Гарвардской школы общественного здоровья (на основе статистики, собранной в США, и модельных расчётов), смертность от свиного гриппа составляет 0,007 % от числа заболевших. Этот показатель ниже, чем у некоторых форм обычного сезонного гриппа.^[30]

Критика

7 июня 2010 Парламентская Ассамблея Совета Европы одобрила отчёт, критикующий действия Всемирной организации здравоохранения касательно пандемии гриппа H1N1 в 2009 году^[31].

Отчёт обвиняет Всемирную организации здравоохранения, а также правительства стран Европы и учреждений Евросоюза в действиях, приведших к растрате государственных средств и внушению населению необоснованных страхов. Из-за ограниченного масштаба эпидемии, крупные партии закупленной вакцины не были использованы^[32]. В одной Германии руководство федеральных земель впустую потратило на вакцины 239 миллионов евро^[33]

См. также

• Грипп
• Вспышка вируса гриппа H1N1 в 2009 году
• Вирусология
• Птичий грипп
• Вакцина для профилактики гриппа
• Испанский грипп
• Тяжёлый острый респираторный синдром (SARS)

Примечания

Литература

• Инфекционные болезни свиней, Феникс, 2007, ISBN 978-5-222-12183-2.

Ссылки

	Свиной грипп на Викискладе?

• Свиной грипп на сайте Всемирной организации здравоохранения
• Свиной грипп на сайте Центров по контролю и профилактике заболеваний США
• Временные методические рекомендации по лечению и профилактике гриппа A/H1N1 на сайте Министерства здравоохранения и социального развития РФ
• Временные методические рекомендации «Схемы лечения и профилактики гриппа, вызванного вирусом типа А/H1N1» — Информационное письмо Минздравсоцразвития РФ № 24-0/10/1-5039 от 25 августа 2009 г. (в редакции от 03 ноября 2009 г.)
• Временные методические рекомендации «Схемы лечения и профилактики гриппа, вызванного вирусом типа А/H1N» — информационное письмо Минздравсоцразвития РФ № 24-0/10/1-5039 от 25 августа 2009 г.
• Профилактика и лечение гриппа: рекомендации населению на сайте Министерства здравоохранения и социального развития РФ в виде презентации

Респираторные вирусные инфекции (МКБ-10: J00-06.00-06., J30-39.30-39.)
Грипп	Свиной грипп  • Птичий грипп  • Испанский грипп
Другие ОРВИ	Парагрипп  • Аденовирусы  • Риновирусы  • Реовирусы  • Респираторная синцитиальная инфекция

Пандемия свиного гриппа в 2009 году
Хронология пандемии свиного гриппа в 2009 году
Страны	Австрия • Бразилия • Канада • Китай • Коста-Рика • Дания • Германия • Ирландия • Израиль • Мексика • Нидерланды • Новая Зеландия • Перу • Панама • Испания • Южная Корея • Швейцария • Великобритания • США
Связанные статьи	Свиной грипп • Гриппоподобное заболевание • Грипп • Грипп A • H1N1 • Действия против свиней
См. также: Пандемия гриппа • Испанский грипп (1918) • H5N1 • Птичий грипп • Гриппоподобное заболевание • Гриппоподобный синдром

Свиной грипп (англ. Swine influenza) — условное название заболевания людей и животных, вызываемого штаммами вируса гриппа. Штаммы, ассоциированные со вспышками так называемого «свиного гриппа», обнаружены среди вирусов гриппа серотипа C и подтипов серотипа А (А/H1N1, А/H1N2, А/H3N1, А/H3N2 и А/H2N3). Эти штаммы известны под общим названием «вирус свиного гриппа». Свиной грипп распространён среди домашних свиней в США, Мексике, Канаде, Южной Америке, Европе, Кении, материковом Китае, Тайване, Японии и других странах Азии^[2]. При этом вирус может циркулировать в среде людей, птиц и других видов; этот процесс сопровождается его мутациями^[3].

Название «свиной грипп» широко распространялось в СМИ в начале 2009 года для обозначения пандемии^[1]. Внезапное объявление ВОЗ пандемии привело к путанице в понимании определения пандемии, её пересмотру и к пониманию того, что нет единого и универсального определения пандемии^[1][4].

Эпидемиология

Передача вируса от животного к человеку мало распространена, и правильно приготовленная (термически обработанная) свинина не может быть источником заражения. Передаваясь от животного к человеку, вирус не всегда вызывает заболевание и часто выявляется только по наличию антител в крови человека. Случаи, когда передача вируса от животного к человеку приводит к заболеванию, называют зоонозным свиным гриппом. Люди, работающие со свиньями, подвергаются риску заражения этим заболеванием, тем не менее с середины двадцатых годов XX века (когда впервые стала возможной идентификация подтипов вируса гриппа) было зарегистрировано всего лишь около 50 таких случаев. Некоторые из штаммов, вызвавших заболевание у людей, приобрели способность передаваться от человека к человеку. Свиной грипп вызывает у человека симптомы, типичные для гриппа и ОРВИ. Вирус свиного гриппа передается как через непосредственный контакт с заражёнными организмами, так и воздушно-капельным путём (см. Механизм передачи возбудителя инфекции).

Этиология

Основная статья: H1N1

Вспышка нового штамма вируса гриппа в 2009 году, получившая известность как «свиной грипп», была вызвана вирусом подтипа H1N1, обладающим наибольшим генетическим сходством с вирусом свиного гриппа. Происхождение этого штамма точно не известно. Тем не менее Всемирная организация по охране здоровья животных (World Organization for Animal Health) сообщает, что эпидемическое распространение вируса этого же штамма не удалось установить среди свиней^[5]. Вирусы этого штамма передаются от человека к человеку^[6] и вызывают заболевания с симптомами, обычными для гриппа^[7].

Свиньи могут быть инфицированы вирусом гриппа человека, и именно это могло произойти как во время пандемии Испанского гриппа, так и вспышки 2009 года.

Патогенез

В целом механизм воздействия данного вируса аналогичен таковому при поражении другими штаммами вируса гриппа. Входными воротами инфекции является эпителий слизистых оболочек дыхательных путей человека, где происходит его репликация и репродукция. Наблюдается поверхностное поражение клеток трахеи и бронхов, характеризующееся процессами дегенерации, некроза и отторжения поражённых клеток.

Развитие патологического процесса сопровождается вирусемией, длящейся 10 −14 дней, с преобладанием токсических и токсико-аллергических реакций со стороны внутренних органов, в первую очередь сердечно-сосудистой и нервной систем.

Главным звеном в патогенезе является поражение сосудистой системы, проявляющееся повышением проницаемости и ломкости сосудистой стенки, нарушением микроциркуляции. Данные изменения проявляются у больных появлением ринорагий (носовых кровотечений), геморрагий на коже и слизистых, кровоизлияниями во внутренние органы, а также приводят к развитию патологических изменений в лёгких: отёку легочной ткани с множественными кровоизлияниями в альвеолы и интерстиций.

Падение тонуса сосудов приводит к возникновению венозной гиперемии кожи и слизистых оболочек, застойному полнокровию внутренних органов, нарушению микроциркуляции, диапедезным кровоизлияниям, на более поздних сроках — тромбозам вен и капилляров.

Данные сосудистые изменения также вызывают гиперсекрецию ликвора с развитием циркуляторных расстройств, приводящих к внутричерепной гипертензии и отёку мозга^[8].

Клиника

Основные симптомы совпадают с обычными симптомами гриппа^[9] — головная боль, повышение температуры, кашель, насморк. Также появляются диарея, рвота, боли в животе. Существенную роль в патогенезе играет поражение лёгких и бронхов вследствие усиления экспрессии ряда факторов — медиаторов воспаления (TLR-3, γ-IFN, TNFα и др.), что приводит к множественному повреждению альвеол, некрозу и геморрагии^[10]
Высокая вирулентность и патогенность этого штамма вируса может быть обусловлена способностью неструктурного белка NS1 (присущего этому вирусу) ингибировать продукцию интерферонов I типа инфицированными клетками^[11]. Дефектные по этому гену вирусы оказываются существенно менее патогенными^[12].

Диагностика

Клинически течение данного заболевания в целом совпадает с течением заболевания при инфицировании другими штаммами вируса гриппа. Достоверный диагноз устанавливается при серотипировании вируса.

Профилактика

В целях первичной специфической профилактики (прежде всего лиц категории риска) в РФ и за рубежом проводится ускоренная разработка и регистрация специфических вакцин на основе выделенного штамма возбудителя. Эпидемиологи приветствуют также вакцинацию от «сезонного» гриппа, содержащую антитела против повреждающих агентов (белков) трёх, отличающихся от «свиного» штамма видов вируса.

В памятке ВОЗ о высокопатогенном гриппе указывается на необходимость исключить близкий контакт с людьми, которые «кажутся нездоровыми, имеющие высокую температуру тела и кашель». Рекомендуется тщательно и достаточно часто мыть руки с мылом. «Придерживайтесь здорового образа жизни, включая полноценный сон, употребление здоровой пищи, физическую активность»^[13]. При должной термообработке вирус погибает. Первичная неспецифическая профилактика направлена на предотвращение попадания вируса в организм и на усиление неспецифического иммунного ответа для предотвращения развития заболевания.

Лечение

Лечение заболевания, вызванного штаммами вируса «свиного» гриппа, по сути не отличается от лечения так называемого «сезонного» гриппа. При выраженных явлениях интоксикации и нарушениях кислотно-щелочного баланса проводится дезинтоксикационная и корректирующая терапия.

По словам главного специалиста по инфекционным болезням Москвы Николая Малышева, препараты, которые содержат парацетамол в своем составе, в большинстве случаев работают только симптоматически, т.е. убирают высокую температуру и снимают озноб. При этом никакого существенного воздействия на вирус гриппа они не оказывают. Другая категория препаратов, которая достаточно широко рекламируется, большей частью является по сути лекарствами с высокой эффективностью при начальных симптомах обычного ОРВИ, не вызванного штаммами гриппа.

Лечение тяжелых и средней степени тяжести случаев направлено на недопущение первичной вирусной пневмонии, обычно протекающей тяжело и вызывающей геморрагии и выраженную дыхательную недостаточность, и на профилактику присоединения вторичной бактериальной инфекции, также часто обуславливающей развитие пневмонии.

Показана также симптоматическая терапия. Из жаропонижающих препаратов большинством специалистов рекомендуются препараты содержащие ибупрофен и парацетамол (не рекомендуется использовать средства, содержащие аспирин, в связи с риском развития синдрома Рея^[14]).

Срочное обращение в медицинские учреждения (вызов скорой помощи) необходимо при признаках выраженной дыхательной недостаточности, угнетения мозговой деятельности и нарушений функции сердечно-сосудистой системы: одышки, нехватке дыхания, цианозе (посинения кожи), обмороке, появлении окрашенной мокроты, низком кровяном давлении, появлении болей в груди.

Обязательное обращение к врачу (как правило, в поликлинику по месту жительства) необходимо при высокой температуре, не снижающейся на 4-й день, выраженном ухудшении состояния после временного улучшения.

Рекомендации по профилактике и лечению гриппа Минздрава РФ

Министерство здравоохранения Российской Федерации выпустило «Временные методические рекомендации по лечению и профилактике гриппа A/H1N1» Архивная копия от 4 ноября 2009 на Wayback Machine^[15].

Временные методические рекомендации по схемам лечения и профилактики гриппа, вызванного вирусом типа А/H1N1, для взрослого и детского населения были подготовлены совместно с ведущими научно-исследовательскими институтами РАМН: НИИ гриппа, НИИ эпидемиологии и микробиологии им. Н. Ф. Гамалеи, ФГУ «Научно-исследовательский институт детских инфекций» и НИИ пульмонологии ФМБА России. От международных рекомендаций они отличаются наличием в них указаний на использование препаратов с недоказанной клинической эффективностью.

Эпидемии, вызванные вирусом гриппа H1N1

Основная статья: H1N1

Вспышка гриппа в 1918 году

Вспышка гриппа в 1976 году

В 1976 г. вспышка свиного гриппа в конце зимы на военной базе в США породила страхи в отношении опустошительной пандемии. Президент Джеральд Форд объявил о плане вакцинации каждого жителя страны. К концу года от нового штамма было вакцинировано 40 миллионов из примерно 200 миллионов американцев, но пандемии не произошло, а доверие к общественному здравоохранению пострадало. Свиной грипп 1976 года: уроки прошлого

Вспышка гриппа в 1988 году

Вспышка гриппа в 2007 году

20 августа 2007 года Департамент Сельского хозяйства Филиппин зарегистрировала вспышку гриппа H1N1 на свинофермах провинции Nueva Ecija и центрального Лусона.

Пандемия гриппа A/H1N1 2009

В апреле-мае 2009 года вспышка нового штамма вируса гриппа^[16] наблюдалась в Мексике и США. Всемирная организация здравоохранения (ВОЗ) и Центры по контролю и профилактике заболеваний США (CDC)^[17] выразили серьёзную обеспокоенность этим новым штаммом по причине того, что существует возможность его передачи от человека к человеку, имеется высокая смертность в Мексике, а также потому, что этот штамм может перерасти в пандемию гриппа. 29 апреля на экстренном заседании ВОЗ повысила уровень пандемической угрозы с 4 до 5 баллов (из 6 возможных) ^[18].

По состоянию на 27 августа 2009 года^[19] зарегистрировано около 255 716 случаев инфицирования гриппом A/H1N1 и 2 627 смертей в более чем 140 регионах мира.^[20] В целом заболевание этим гриппом протекает по классическому сценарию, частота осложнений и смертей (чаще вследствие пневмонии) не превышает средние показатели при сезонном гриппе.

На данный момент идут споры вокруг того, как же всё-таки называть данный штамм гриппа. Так, 27 апреля 2009 г. «свиной грипп» назвали «Калифорния 04/2009» ^[21], 30 апреля производители свинины выступили за переименование «свиной грипп» в «мексиканский» ^[22]; чёткого ненаучного наименования не придумано до сих пор.

Пятый уровень угрозы был объявлен в конце апреля 2009 года: в соответствии с принятой ВОЗ классификацией, этот уровень характеризуется распространением вируса от человека к человеку по меньшей мере в двух странах одного региона.

11 июня 2009 года ВОЗ объявила^[23] о пандемии свиного гриппа, первой пандемии за последние 40 лет. В этот же день ему была присвоена шестая степень угрозы (из шести). Степень угрозы ВОЗ не характеризует патогенность вируса (то есть опасность заболевания для жизни людей), а указывает на его способность к распространению. Т.о., любой грипп, передающийся от человека к человеку, достигает шестой степени угрозы.

Тем не менее, опасения ВОЗ связаны с генетической новизной штамма Калифорния и его потенциальной способностью к дальнейшей реассортации, вследствие чего возможно возникновение более агрессивных вариантов инфекции. Тогда, по аналогии с наиболее разрушительными пандемиями прошлого века, этот вирус приведет к серьезным людским потерям спустя некоторый (обычно полугодовой) период, сопровождающийся относительно умеренной летальностью.

Вспышка гриппа в 2016 году

Грипп и общество: социально-экономические последствия

В Гонконге в связи с угрозой эпидемии свиного гриппа с 1 мая 2009 года введен режим чрезвычайной ситуации. Гостиница, где остановилась заболевшая туристка, блокирована и оцеплена полицией^[24]

Профилактические мероприятия усилили социальную напряженность и вылились в Египте в небольшой крестьянский бунт, когда 3 мая 300—400 свиноводов собрались на улицах Каирa, чтобы спасти от угрозы уничтожения своих кормильцев. Демонстранты бросали в полицейских камни и бутылки, поэтому спецподразделения полиции по борьбе с уличными беспорядками были вынуждены применить резиновые дубинки и слезоточивый газ, чтобы разогнать протестующих^[25].

Президент США Барак Обама 24 октября 2009 года объявил чрезвычайное положение в связи с гриппом А/H1N1^[26]. Как сообщают представители Белого дома, Обама подписал соответствующий акт, в котором говорится, что грипп А/H1N1 является национальной угрозой для США.

Новый штамм в 2020 году

В конце июня 2020 года в Китае местными учеными был обнаружен новый штамм гриппа, который получил название G4 EA H1N1, который обладает характерными пандемическими свойствами. Такой вывод ученые сделали после того, как были зафиксированы случаи передачи вируса от свиней человеку^[27].

Прогноз течения болезни и показатели смертности

Прогноз течения заболевания условно благоприятный, при адекватном иммунном статусе и у лиц, не входящих в группы риска, время заболевания не превышает 2 недель и заканчивается полным выздоровлением. Трудоспособность полностью восстанавливается.

При сниженном иммунитете, а также у лиц, входящих в группы риска, возможно развитие тяжелых, опасных для жизни осложнений.

Смертность при инфицировании данным вирусом не превышает смертности при поражении другими штаммами вируса^[28][29][30]. Согласно данным Гарвардской школы общественного здоровья (на основе статистики, собранной в США, и модельных расчётов), смертность от свиного гриппа составляет 0,007 % от числа заболевших. Этот показатель ниже, чем у некоторых форм обычного сезонного гриппа^[31].

После перенесенного свиного гриппа у человека появляется типоспецифический иммунитет примерно на 1 год.^[32]

Критика

7 июня 2010 года Парламентская ассамблея Совета Европы одобрила отчёт, критикующий действия ВОЗ касательно пандемии гриппа H1N1 в 2009 году^[33].

Отчёт обвиняет Всемирную организацию здравоохранения, а также правительства стран Европы и учреждений Евросоюза в действиях, приведших к растрате государственных средств и внушению населению необоснованных страхов. Из-за ограниченного масштаба эпидемии, крупные партии закупленной вакцины не были использованы^[34]. В одной Германии руководство федеральных земель впустую потратило на вакцины 239 миллионов евро^[35].

По мнению президента межрегионального Общества фармакоэкономических исследований, заместителя председателя Формулярного комитета РАМН, доктора медицинских наук, профессора П. А. Воробьева: ажиотаж вокруг свиного гриппа, и все спекуляции на данную тему организованы с одной целью — побольше заработать (сверхприбыли фармацевтических компаний продвигающих вакцины и противовирусные препараты)^[36].

См. также

• Грипп
• Вспышка вируса гриппа H1N1 в 2009 году
• Вирусология
• Птичий грипп
• Вакцина для профилактики гриппа
• Испанский грипп
• Тяжёлый острый респираторный синдром (SARS)

Примечания

Литература

• Инфекционные болезни свиней, Феникс, 2007, ISBN 978-5-222-12183-2.

Ссылки

• Свиной грипп на сайте Центров по контролю и профилактике заболеваний США
• Какой грипп тяжелее: свиной или сезонный, и какова вероятность заболеть?

Эта страница в последний раз была отредактирована 29 декабря 2022 в 16:01.

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Обычно почти сразу, изредка в течении часа.