How is swine flu transmitted from pigs to humans: What People Who Raise Pigs Need To Know About Influenza (Flu)
What People Who Raise Pigs Need To Know About Influenza (Flu)
As someone who raises pigs, whether for show (e.g. 4-H or Future Farmers of America [FFA]) or as part of a farming operation (i.e. commercial pork producer), you may have questions about influenza (the flu) in both pigs and people. This document addresses what is known about flu viruses in pigs and people and what people in contact with pigs can do to reduce the risk of getting sick or of getting their pigs sick.
Influenza Virus Infections in Pigs and People
There are many causes of respiratory disease in pigs, including influenza. Among influenza types, only type A influenza viruses are known to infect pigs. Most of the influenza viruses circulating in swine are different from those circulating in people. When viruses that normally circulate in pigs infect humans, they are termed “variant” viruses.
At this time, there are three main flu viruses that circulate in U.S. pigs: h2N1, h2N2 and h4N2. These viruses do not usually infect people and are genetically different from the h2N1 and h4N2 viruses that commonly circulate in people. When the flu viruses circulating in pigs are very different from the human flu viruses causing illness in people, people may have little to no immune protection against the viruses circulating in pigs. Also, human flu vaccines probably would not offer protection against the viruses that are found in pigs.
Flu viruses commonly infect pigs and pig herds and can result in high rates of illness among pigs, but few deaths.
Signs of influenza in pigs include:
- Coughing (“barking”)
- High fevers
- Breathing difficulties
- Discharge from the nose
- Going off feed
However, pigs also may become infected with flu viruses from people and from birds. This cross-species spread and possible mixing of flu viruses can lead to new and very different flu viruses that might gain the ability to spread easily between people.
Questions & Answers about Influenza in Pigs
Q. How does influenza spread among pigs?
A. Flu viruses are thought to spread among pigs in the same way that human influenza viruses spread among people. That is mainly through close contact between infected and uninfected pigs and possibly from contact by an uninfected pig with an object contaminated by an infected pig. Pigs also can be infected by flu viruses from their human caretakers.
Q. Can influenza virus infections be prevented in pigs?
A. It may be possible to lessen the risk of infections in pigs and/or severity of disease by following these management strategies:
- Vaccinating herds
- Using good biosecurity measures
- Practicing good hygiene
- Vaccinating pig caretakers with seasonal influenza vaccine
- Using proper ventilation systems
Q. What about flu vaccines for pigs?
A. Flu vaccines for pigs can help, but are not 100% effective. Sometimes the vaccine used may not protect against the virus or viruses circulating. In addition, current vaccines may not be effective in young pigs due to interference from antibodies received from the sow. Generally, protection of young pigs is achieved by vaccinating sows; however, those maternal antibodies are not fully protective for the young pig and decrease by the time they are 10 to 13 weeks old or sooner. Producers may vaccinate their animals after maternal antibodies decrease.
Q. How can veterinarians help?
A. You should work together with your veterinarian to develop management strategies to reduce the spread of influenza among herds and to prevent the introduction and spread of flu viruses between pigs, people, and birds.
Q. Can people get influenza from eating pork?
A. Flu viruses in pigs have not been shown to be transmissible to people through eating properly handled and prepared pork (pig meat) or other products derived from pigs. For more information about the proper handling and preparation of pork, visit the USDA website fact sheet Fresh Pork from Farm to Tableexternal icon.
Q. What about 2009 h2N1?
A. The 2009 h2N1 flu virus was first detected in people in the United States in April 2009. It was a new influenza virus among humans which was able to spread easily from person-to-person, causing the first influenza pandemic in more than 40 years. This virus had two genes from flu viruses that normally circulate in pigs in Europe and Asia, three genes that normally circulate in North American pigs, and genes from flu viruses from birds and people as well. This particular virus, however, had not been detected in North American pigs before April 2009. The 2009 h2N1 flu virus is now considered a human influenza virus.
In October 2009, the first case of 2009 h2N1 flu virus infection in a pig in the United States was confirmed. Pig infections with the 2009 h2N1 flu virus also have been found in other countries, including Canada, Australia and Argentina. USDA and other researchers conducted studies in pigs that showed that the 2009 h2N1 virus caused illness in swine similar to those of other well-known, circulating swine flu viruses.
Q. How common are variant infections in people?
A. Human infections with influenza A viruses normally found in swine (now called variant viruses) are rare events, but the frequency of such detections has increased in recent years. This could be occurring for a number of reasons including: improved laboratory methods for testing for these viruses in the United States, increased surveillance in the United States for influenza, or it is possible that the increased frequency of detection of variant viruses represents a true increase in the number of such cases, possibly occurring from exposure to infected swine or through subsequent, limited human-to-human transmission.
The Flu Can Spread from Pigs to People and from People to Pigs
- Human flu viruses can infect pigs and can introduce new flu viruses into the swine population.
- The flu viruses that normally circulate in pigs can infect people, but this is not common.
- In 2005 and 2006, three cases of infection with flu viruses that normally circulate in swine (“variant viruses”) were reported in people.
- Beginning in 2007, about three to four of these cases were reported per year. This increased reporting may partially be because human infection with novel (non-human) flu viruses became nationally notifiable in 2007. That means that when a human infection with a non-human influenza virus is detected in people, it must be reported to federal authorities.
- In 2012, 313 variant cases were reported to CDC, the largest number of cases reported in a single year.
- Reported Infections with Variant Influenza Viruses in the United States includes the most up to date information about infections with variant viruses that have been reported to CDC.
- The flu viruses that commonly spread in humans are different from the ones that spread in pigs.
- People who get vaccinated annually against human influenza can still get sick from swine influenza viruses.
- Pigs that have been vaccinated for swine influenza can still get sick from some human influenza viruses.
- When people are infected with variant flu viruses, the symptoms are basically the same as those caused by illness from human influenza viruses and can include fever, cough, body aches, headaches, fatigue and runny or stuffy nose. There may also be vomiting or diarrhea.
- Most reported cases of human infection with variant viruses have occurred in people who have been near infected pigs in public settings such as fairs or petting zoos, or who work directly with infected pigs.
- Investigations of human cases of infection with variant viruses are routine. These investigations are designed to determine if the flu virus in question is spreading from person to person. It is important to know if flu viruses common among pigs are spreading among people so that cases in other people can be prevented.
Preventing the Spread of Flu Viruses Between People and Pigs
Like everyone else, animal caretakers tending pigs should get annual seasonal influenza vaccines. Although vaccination of people with seasonal influenza vaccine probably will not protect against infection with variant influenza viruses (because they are substantially different from human influenza A viruses), vaccination is important to reduce the risk of transmitting seasonal influenza A viruses from ill people to other people and to pigs. Seasonal influenza vaccination might also decrease the potential for people or pigs to become co-infected with both human influenza viruses and influenza viruses from pigs. Such dual infections are thought to be the source of reassortment of two different influenza A viruses which can lead to a new influenza A virus that has a different combination of genes, and which could pose a significant public or animal health concern.
Other routine measures to take:
- Wash your hands frequently with soap and running water before and after exposure to animals,
- Avoid close contact with animals that look or act ill, when possible, and
- Avoid contact with pigs if you are experiencing flu-like symptoms.
If you must come in contact with pigs while you are sick, or if you must come in contact with pigs that are known or suspected to be infected, or their environment, you should use appropriate protective measures (for example, wear protective clothing, gloves, masks that cover your mouth and nose, and other personal protective equipment) and practice good respiratory and hand hygiene.
If you or your family members become sick with flu-like symptoms and need medical treatment, take the following steps:
- Contact your health care provider and let them know about your symptoms and that you work with swine. Your doctor may prescribe treatment with influenza antiviral medications and may want a nose and throat specimen collected from you for testing at your state health department.
- Avoid or limit contact with household members and others until you have been fever-free for 24 hours without the use of fever reducing medications, and avoid travel.
- Practice good respiratory and hand hygiene. This includes covering your mouth and nose with a tissue when coughing or sneezing and putting used tissues in a waste basket. If tissues are not available, cough or sneeze into your upper sleeve. Always wash your hands after coughing or sneezing. This is to lower the risk of spreading whatever virus you have to others.
- Avoid or limit contact with pigs as much as possible. Stay away from pigs for 7 days after symptoms begin or until you have been fever-free for 24 hours without the use of fever reducing medications, whichever is longer. (This is to protect your pig(s) from getting sick.)
Almost all influenza cases in humans are caused by human flu viruses, not viruses from swine. However, if you are infected with an influenza virus of animal origin, the health department will want to talk with you about your illness and make sure that other people you live and work with are not sick with the same virus.
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Centers for Disease Control and Prevention
U. S. Department of Agriculture
Factsheet on swine influenza in pigs
Swine influenza – animal facts
Influenza in swine is an acute viral infection of the respiratory tract in pigs caused by type A influenza viruses. The mortality rate is low in pigs and recovery usually occurs within 7–10 days. Swine-origin (or swine-lineage) influenza virus (SIV) infections also occur in poultry and humans, but interspecies transmission is considered a rare event. Three subtypes of influenza A virus have been found to circulate in pigs: A(h2N1), A(h2N2) and A(h4N2). They are all swine influenzas, i.e. they are well adapted to their swine hosts. They are different from human influenza viruses with the same nomenclature and can be distinguished from them antigenically.
Current influenza viruses in European pigs
Avian-like swine A(h2N1) influenza viruses (SIVs) of the subtypes A(h2N1), A(h4N2) and A(h2N2) are enzootic and widespread in swine producing regions of Western Europe. In Central Europe, SIV activity is low and the circulation of h4N2 and h2N2 remains to be confirmed. The classical A(h2N1) influenza virus – which was a direct descendant of the 1918 human influenza pandemic virus and is still present in pigs in the Americas and Asia – has not been detected in European pigs for over 15 years. Contemporary swine A(h4N2) influenza viruses in European pigs descend from early human influenza A(h4N2) pandemic strains, and have diverged substantially genetically and antigenically from contemporary human viruses. The ‘triple re-assortant’ (TRA) swine influenza A(h2) viruses are named like this because they contain genes from avian, human and swine influenza viruses. The TRA influenza viruses seen in North America (including influenza A(h4N2) viruses, also observed in Asia) have not been detected in European pigs to date.
Current Swine influenza viruses circulating in the US and Asia
The epidemiology and virology of SIVs in Europe and the United States seem to be quite different. The TRA viruses of the type S-OtrA(h4N2) seen in pigs and humans in the United States have not been found in Europe to date. The main SIVs circulating in pig herds in the United States in recent years have been swine TRA A(h2N1), A(h4N2) and A(h2N2) viruses. These TRAs have also been found in Asia.
An important point is that there is little, if any, movement of live pigs between Europe and other continents. Indeed, it is not legal for live pigs to be imported from the United States to Europe.
Asia, especially China, has the largest human and pig populations in the world, and seems to be the only world region frequently importing pigs (and potentially SIVs) from other continents. The most commonly circulating influenza viruses in Asia are the classical swine A(h2N1) virus, human-origin A(h4N2) viruses, the American triple reassortant (TRA) A(h2N2) virus, the European avian-like A(h2N1) virus and all their reassortant variants.
Surveillance for swine influenza in European pigs
Swine influenza in pigs is not notifiable at the European Union level. Indeed, worldwide structured surveillance is very weak because swine influenzas are not considered to be a major threat to veterinary health. Through a project called ESNIP3, funded by the European Commission (DG-Research), the surveillance of influenza in pigs in numerous Member States is conducted in a coordinated way and the outputs from it are analyzed. This is supported by largely industry driven activity in a number of countries while formally funded programmes at national level are more limited. However, ECDC is not aware of any integrated animal-human influenza surveillance in Europe.
The pig as mixing vessel theory
Most swine influenza viruses are reassortants with mixtures of human, avian and swine virus genes. This supports the classical theory that pigs are susceptible to both human and avian influenza viruses, and that they can then serve as ‘mixing vessels’ for those viruses in pigs that are infected with two or more viruses. Antigenic ‘drift’ within swine influenza virus lineages does occur but it is less prominent than antigenic ‘drift’ in human influenza viruses. A significant fraction of the currently circulating influenza A(h2N1) viruses in pigs derives from the 2009 pandemic influenza A(h2N1) virus, now officially designated A(h2N1)pdm09 influenza virus. The further reassortment of previously circulating pig influenza viruses such as those of types A(h2N1), A(h2N2) and A(h4N2) with the A(h2N1)pdm09 influenza virus is therefore possible.
h2N1 flu (swine flu) – Symptoms and causes
The h2N1 flu, commonly known as swine flu, is primarily caused by the h2N1 strain of the flu (influenza) virus. h2N1 is a type of influenza A virus, and h2N1 is one of several flu virus strains that can cause the seasonal flu. Symptoms of the h2N1 flu are the same as those of the seasonal flu.
In the spring of 2009, scientists recognized a particular strain of flu virus known as h2N1. This virus is a combination of viruses from pigs, birds and humans that causes disease in humans. During the 2009-10 flu season, h2N1 caused the respiratory infection in humans that was commonly referred to as swine flu. Because so many people around the world got sick, in 2009 the World Health Organization (WHO) declared the h2N1 flu to be a pandemic. In August 2010, WHO declared the pandemic over. After the pandemic was over, the h2N1 flu virus became one of the strains that cause seasonal flu.
The flu vaccine can now help protect against the h2N1 flu (swine flu). The h2N1 flu virus strain is included in the seasonal flu vaccine, including the vaccine for 2020-21.
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The signs and symptoms of flu caused by the h2N1 virus are similar to those of infections caused by other flu strains and can include:
- Fever, but not always
- Sore throat
- Runny or stuffy nose
- Watery, red eyes
- Body aches
- Nausea and vomiting
Flu symptoms develop about one to three days after you’re exposed to the virus.
When to see a doctor
It’s not necessary to see a doctor if you’re generally healthy and develop flu signs and symptoms, such as fever, cough and body aches. Call your doctor, however, if you have flu symptoms and you’re pregnant or you have a chronic disease, such as asthma, emphysema, diabetes or a heart condition, because you have a higher risk of flu complications.
If you have emergency signs and symptoms of the flu, get medical care right away. For adults, emergency signs and symptoms can include:
- Difficulty breathing or shortness of breath
- Chest pain
- Ongoing dizziness
- Worsening of existing medical conditions
- Severe weakness or muscle pain
Emergency signs and symptoms in children can include:
- Difficulty breathing
- Blue lips
- Chest pain
- Severe muscle pain
- Worsening of existing medical conditions
Influenza viruses such as h2N1 infect the cells that line your nose, throat and lungs. The virus enters your body when you inhale contaminated droplets or transfer live virus from a contaminated surface to your eyes, nose or mouth.
You can’t catch swine flu from eating pork.
If you live in or travel to an area where many people are infected with the h2N1 virus, you may be exposed to the virus.
Influenza complications include:
- Worsening of chronic conditions, such as heart disease and asthma
- Neurological signs and symptoms, ranging from confusion to seizures
- Respiratory failure
The Centers for Disease Control and Prevention (CDC) recommends annual flu vaccination for everyone age 6 months or older. Each year’s seasonal flu vaccine protects against the three or four influenza viruses that are expected to be the most common during that year’s flu season. The flu vaccine can reduce your risk of the flu and its severity and lower the risk of having serious illness from the flu and needing to stay in the hospital.
Flu vaccination is especially important in the 2020-21 flu season because the flu and coronavirus disease 2019 (COVID-19) cause similar symptoms. Flu vaccination could reduce symptoms that might be confused with those caused by COVID-19. Preventing the flu and reducing the severity of flu illness and hospitalizations could also lessen the number of people needing to stay in the hospital.
The flu vaccine is available as an injection and as a nasal spray. The nasal spray is approved for use in healthy people ages 2 through 49 years old. The nasal spray isn’t recommended for some groups, such as pregnant women, children between 2 and 4 years old with asthma or wheezing, and people who have compromised immune systems.
These measures also help prevent the flu and limit its spread:
- Wash your hands thoroughly and frequently. Use soap and water, or if they’re unavailable, use an alcohol-based hand sanitizer.
- Cover your coughs and sneezes. Cough or sneeze into a tissue or your elbow. Then wash your hands.
- Avoid touching your face. Avoid touching your eyes, nose and mouth.
- Clean surfaces. Regularly clean often-touched surfaces to prevent spread of infection from a surface with the virus on it to your body.
- Avoid contact. Stay away from crowds if possible. Avoid anyone who is sick. If you’re at high risk of complications from the flu — for example, you’re younger than 5 or you’re 65 or older, you’re pregnant, or you have a chronic medical condition such as asthma — consider avoiding swine barns at seasonal fairs and elsewhere.
During the COVID-19 pandemic, both COVID-19 and the flu may be spreading at the same time. Your local health department and the CDC may suggest other precautions to reduce your risk of COVID-19 or the flu. For example, you may need to practice social distancing (physical distancing) and stay at least 6 feet (2 meters) from others outside your household. You may also need to wear a cloth face mask when around people outside your household.
Feb. 24, 2021
Swine Influenza – an overview
Viruses That Cause Diseases Represent a Small Fraction of the Viral Community
Diseases such as smallpox, rabies, AIDS, bird flu, swine flu, herpes, hepatitis, Japanese encephalitis, cassava mosaic disease as well as some of the more common, chickenpox, and the ever prolific common cold have helped perpetuate the bias toward viewing viruses as major challenges to humans, either directly through affecting our health or through affecting the health of livestock and crops. Indeed, much of the historical and current research resolved around determining the causative agent of virus diseases that often negatively affect their hosts, whether by causing disease in humans, plants, or animals or by killing their microbial hosts. Not only can virus diseases take a large toll on human life, some infections are seen as development concerns affecting education, income, productivity, and economic growth. Economic losses due to viruses derive from the treatment of the diseases they cause, their prevention, control of their vectors, as well as a myriad of varying consequences of social, economic and political impact, and the research aimed at developing control strategies—including vaccines and their administration. In agriculture viruses can lead to a complete crop loss due to reductions in plant growth and vigor, decreases in product quality (and hence, market value), investments in the development of prevention and control strategies, the implementation of quarantine programs, development of detection protocols, and more.
Although some virus diseases, such as smallpox and poliomyelitis, have been eradicated or almost wiped out, many diseases persist with limited little success at management and containment. In addition, new infectious diseases are emerging and old ones are reappearing after a significant decline in incidence. The term emerging disease refers to the appearance of an as yet unrecognized infection, or a previously recognized infection that has expanded into a new ecological niche or geographical zone. Emerging or re-emerging diseases are typically zoonotic, i.e., the infection can be spread between animals and humans and is often accompanied by some change in pathogenicity. HIV/AIDS is an example. HIV crossed into humans from chimpanzees in the 1920s presumably because of the bush meat trade—the hunting and killing of chimpanzees and other animals for human consumption. Severe acute respiratory syndrome (SARS), avian influenza, and Zika are more recent emerging zoonotic diseases. Zoonoses have been known since early historical times, but their incidence has quadrupled in the last half-century, mainly because of increasing human encroachment into wildlife habitats, air travel, and wildlife trafficking.
As this book will present diseases of viral etiology no further details will be provided in this section. Suffice to say that viruses can inflict damage in ways not caused by other pathogens mainly because virus infections are not always easy to control or prevent. However, it now appears that viruses with bad intent represent only a small fraction of a massive viral community and that a large number of viruses are unknown to science. Technologies of DNA and RNA deep sequencing, as well as genomics and metagenomics, are rapidly uncovering new species of viruses from seemingly healthy hosts. A diverse, abundant, and underappreciated viral community exists on and within us, even within our own genomes. Unlike the influenza- and Ebola-like viruses, these viruses establish a balanced coexistence by regulating their gene expression (possibly involving the use of noncoding RNAs such as microRNAs) thus allowing them to exist for the host’s entire lifetime under the radar of the host’s defense systems.
Swine flu | disease | Britannica
Swine flu, also called swine influenza, hog flu, or pig flu, a respiratory disease of pigs that is caused by an influenza virus. The first flu virus isolated from pigs was influenza A h2N1 in 1930. This virus is a subtype of influenza that is named for the composition of the proteins hemagglutinin (H) and neuraminidase (N) that form its viral coat. Since the 1930s three other subtypes of flu viruses also have been isolated from pigs, including h2N2, h4N1, and h4N2. The emergence of h4N2 in pigs occurred in the late 1990s and is suspected of having been transmitted to pigs from humans. Although swine influenza viruses are similar to the influenza viruses that circulate among humans, swine viruses possess distinct antigens (molecules that induce an immune response).
Symptoms and transmission
Between 25 and 30 percent of pigs worldwide carry antibodies to swine influenza viruses, which indicates that these animals have been exposed to swine flu. The disease is endemic in pigs in the United States, and in some regions of that country more than 50 percent of pigs carry antibodies to swine influenza viruses. Infection with any of these viruses causes a flulike illness in pigs, which typically occurs in the fall and early winter. Symptoms of infection include coughing (barking), fever, and nasal discharge, and illness generally lasts about a week.
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The virus is spread rapidly among pigs and is easily spread to birds and humans who come into contact with the pigs or contaminated food or bedding or who inhale infectious particles in the air. Humans infected with swine influenza virus may experience fever and mild respiratory symptoms, such as coughing, runny nose, and congestion. Some persons experience diarrhea, chills, and vomiting. Swine influenza virus rarely causes death in humans.
A well-documented outbreak of swine flu in humans occurred in 1976 in New Jersey, U.S., at Fort Dix army base, where severe respiratory illness was observed in a small group of recruits and caused one death. Although the virus isolated from the recruits was identified as swine influenza, the origin of the virus was unknown.
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Treatment and prevention
There are no specific drugs available for swine flu in pigs, and treatment is thus supportive. Providing a clean and dry environment and keeping infected pigs separate from healthy pigs are essential approaches to controlling the disease. In many cases, antibiotics are administered to prevent the emergence of bacterial infection.
Outbreaks of swine flu in pigs can be prevented through vaccination against the viruses. The spread of the virus among pigs also can be controlled through sanitary practices, such as disinfecting areas that were occupied by infected pigs, disposing of contaminated bedding, and washing hands after handling infected animals.
Learn More in these related Britannica articles:
Prevalent Eurasian avian-like h2N1 swine influenza virus with 2009 pandemic viral genes facilitating human infection
Influenza A virus (IAV) is a global pathogen of humans and a wide range of mammalian and avian species. Reassortment of influenza viruses is a major mechanism to generate progeny viruses with novel antigenic and biological characteristics, which can cause catastrophic human epidemics and pandemics. Historically, pandemic IAVs from 1957, 1968, and 2009 are all reassortants derived from human and animal influenza viruses (1, 2). Pigs, being susceptible to avian, swine, and human IAVs, are regarded as “mixing vessels” in the generation of influenza viruses with pandemic potential (3⇓–5). The emergence of the 2009 pandemic (pdm/09) h2N1 virus vividly illustrates the importance of pigs in new outbreaks (6⇓–8). Therefore, continuous surveillance of swine influenza viruses (SIVs) in pigs and assessment of their zoonotic potential are essential for the preparedness of human pandemics.
China has, arguably, the most complex SIVs ecosystem with classical swine (CS) lineage, North American triple-reassortant (TR) lineage, and Eurasian avian-like (EA) lineage SIVs cocirculating in pigs (9). EA h2N1 SIVs are found in 2001, and gradually become the dominant lineage in China (9⇓–11). However, after 2009, the pdm/09 h2N1 virus in humans has spread back into pig herds around the world (12, 13). Subsequently, reassortants between the swine EA h2N1 virus and human pdm/09 h2N1 virus have been sporadically detected in pigs in China and other countries (10, 14⇓⇓⇓⇓⇓–20), some of which have caused human infections in China (21⇓–23). However, the current prevalence and biological properties of these emergent EA reassortants and their infectivity in human population are unknown.
In this study, we performed an extensive SIVs surveillance program between 2011 and 2018 in 10 provinces with high-density pig populations. We identified a predominant emergent EA reassortant genotype 4 (G4) virus in pigs, which has pdm/09 and TR-derived internal genes and shows efficient infectivity and transmissibility in the ferret model. Serological surveillance among swine workers and general population showed that G4 EA h2N1 viruses have acquired increased human infectivity. Thus, the emergent G4 EA h2N1 viruses pose a serious threat to human health.
EA h2N1 Viruses Exhibit Increased Genetic Diversity since 2013.
To investigate the epidemiological status of SIVs, from 2011 to 2018, we performed active surveillance and collected a total of 29,918 nasal swab samples from normal pigs in slaughterhouses in 10 provinces with high-density pig populations (SI Appendix, Fig. S1). We isolated 136 influenza viruses from these samples, with an isolation rate of 0. 45% (SI Appendix, Table S1). In the same period, 1,016 nasal swabs or lung samples were collected from pigs showing respiratory symptoms in our school’s veterinary teaching hospital, of which 43 were positive for influenza virus, at an isolation rate of 4.23% (SI Appendix, Table S1). Based on sequence analysis of the hemagglutinin (HA) and neuraminidase (NA) genes of the combined 179 SIVs, they were identified as EA h2N1 (n = 165), pdm/09 h2N1 (n = 7), CS h2N1 (n = 1), h4N2 (n = 4), and H9N2 (n = 2) viruses (SI Appendix, Table S1), indicating that EA h2N1 is the predominant subtype virus circulating in pig populations in China. Among them, only EA h2N1 virus was isolated every year, while other SIVs such as CS h2N1 and h4N2 were only found in certain years. Seven pdm/09 h2N1 viruses were only found in 2011, indicating that pdm/09 h2N1 virus was not maintained in pigs even though it was generated from pigs (2). All 43 viruses isolated from diseased pigs were of EA h2N1 subtype. It is noted that the mean virus isolation rates from diseased pigs increased annually from 1.40% in 2011 to 8.21% in 2018, with a sharp increase from 2014 (SI Appendix, Fig. S2), indicating that EA h2N1 viruses are a growing problem in pig farms.
To understand the phylogenetic evolution of the prevailing EA h2N1 viruses, a total of 77 viruses were selected for full genome sequencing on the basis of isolation time and location, with at least one strain sequenced per province (SI Appendix, Table S2). The whole genomes of 77 viruses were analyzed along with all available EA h2N1 sequences from both swine and human viruses in mainland China from 2011 to 2018. Based on the unified swine h2 HA nomenclature system (24), the HA genes of all of the EA h2N1 viruses isolated in the study belonged to clade 1C.2.3 (SI Appendix, Fig. S3). Viruses isolated during 2011–2013 had relative short evolutionary branches. However, long branches leading to several lineages were found in viruses isolated after 2013 (Fig. 1A). NA genes had a similar genetic evolution pattern (SI Appendix, Fig. S3). Notably, also after 2013, the six internal genes exhibited distinct diversity, with multiple origins from original EA, pdm/09, Avian, and TR lineages (SI Appendix, Fig. S3). These results suggest that the genomes of EA h2N1 SIVs have undergone increased diversity since 2013.
Phylogenetic relationship of HA gene and antigenic characterization of EA h2N1 SIVs in China from 2011 to 2018. (A) Phylogenetic tree of HA gene. Phylogenetic tree was estimated using genetic distances calculated by maximum likelihood under the GTRGAMMA + I model. SIVs isolated in this study are green; sequences of viruses with names in black were downloaded from databases. Node labels represent bootstrap values. Viruses labeled with a red triangle were selected for antiserum generation. A full detailed HA gene tree with the consistent topology is shown in SI Appendix, Fig. S3. (Scale bar is in units of nucleotide substitutions per site. ) (B) Antigenic map based on the HI assay data. Open squares and filled circles represent the positions of antisera and viruses, respectively. Clusters were identified by a k-means clustering algorithm. Strains belonging to the same antigenic cluster are encircled in an oval. The vertical and horizontal axes both represent antigenic distance. The spacing between grid lines is 1 unit of antigenic distance, corresponding to a twofold dilution of antiserum in the HI assay. Details of the HI assay data are shown in SI Appendix, Table S5. (C) Antigenic analysis of EA h2N1 and human influenza vaccine strains. Twenty serum samples, collected from 4-y-old children vaccinated with trivalent vaccines (A/Michigan/45/2015 [pdm/09 h2N1] + A/Singapore/INFIMH-16-0019/2016 [h4N2] + B/Colorado/06/2017 [B/Victoria]), were subjected to HI assays. The pdm/09 h2N1 virus A/Michigan/45/2015, human h4N2 virus A/Singapore/INFIMH-16-0019/2016, G1 EA h2N1 virus SW/HN/08/11, and G4 EA h2N1 virus SW/SD/1207/16 were used as antigens. HI titers ≥ 40 were considered positive.
G4 Reassortant EA h2N1 Viruses Have Been Predominant since 2016.
To show viral evolution, we conducted molecular clock phylogenic analysis and genotype characterization (Fig. 2A and SI Appendix, Fig. S4). Based on lineage classification, six genotypes of G1–G6 were found in EA h2N1 viruses from 2011 to 2018 (Fig. 2B). The virus with all eight genes from the “pure” EA h2N1 lineage was designated as G1. G1 viruses were predominately circulating in both southern and northern China from 2011 to 2013 (SI Appendix, Fig. S5). However, prototypical EA h2N1 viruses have largely disappeared since 2014 (Fig. 2B and SI Appendix, Fig. S5). G2, G3, and G6 reassortant EA viruses appeared transiently during 2011–2015. In 2013, two reassortant G4 and G5 viruses emerged in southern China (SI Appendix, Fig. S5). G5 virus possesses the HA, NA, and matrix (M) genes from the original EA h2N1 lineage, the viral ribonucleoprotein (vRNP) genes from the pdm/09 lineage, and the nonstructural (NS) gene from the TR lineage. G5 virus was detected continuously from 2013 to 2017, but it has declined since 2015 and was not found in 2018 (Fig. 2B). Similar to G5, G4 was also a triple reassortant, except its M gene was derived from pdm/09 lineage. G4 virus has shown a sharp increase since 2016, and is the predominant genotype in circulation in pigs detected across at least 10 provinces (Fig. 2B and SI Appendix, Fig. S5).
Phylogenetic analysis of EA h2N1 SIVs in China from 2011 to 2018. (A) Phylogeny and divergence time of the HA gene and genotype evolution of EA h2N1 SIVs. The phylogenetic tree of HA gene was generated by Bayesian Markov Chain Monte Carlo framework, using the GTR substitution model with gamma-distributed among site rate heterogeneity and a “strict molecular clock” model. Colored boxes show the lineage classification of each gene segment of EA h2N1 viruses. Purple node bars represent 95% credible intervals of lineage divergence times. A detailed phylogenetic tree including sequence names is shown in SI Appendix, Fig. S4. (B) Diversity of genotypes of EA viruses isolated from swine in China, 2011–2018.
To assess the zoonotic potential of the G4 reassortant EA viruses, four representative G4 viruses (A/swine/Shandong/1207/2016 [SW/SD/1207/16], A/swine/Hebei/0116/2017 [SW/HB/0116/17], A/swine/Henan/SN13/2018 [SW/HN/SN13/18], and A/swine/Jiangsu/J004/2018 [SW/JS/J004/18]) were selected for further biological characterization. Two G1 strains (A/swine/Henan/08/2011 [SW/HN/08/11] and A/swine/Hebei/T37/2013 [SW/HB/T37/13]) and a pdm/09 h2N1 virus, A/California/04/09 (CA04), were also selected for comparison.
G4 EA h2N1 Viruses Preferentially Bind Human-Like SAα2,6Gal Receptor.
The binding preference of HA to host SAα2,6Gal receptor is a critical determinant for cross-species transmission of IAVs to humans (25, 26). We determined the binding affinity of EA h2N1 viruses to SAα2,3Gal and SAα2,6Gal sialylglycopolymers. Like pdm/09 virus CA04, all four of the G4 EA h2N1 viruses as well as the two G1 viruses bound SAα2,6Gal receptors with high affinity but bound poorly to SAα2,3Gal receptors (SI Appendix, Fig. S6A). Furthermore, all of the EA h2N1 viruses were found to bind to human tracheal epithelial lining to an extent similar to CA04 pdm/09 h2N1 virus, but control avian H5N1 virus showed no binding (SI Appendix, Fig. S6B). Thus, these results demonstrate that G4 EA h2N1 viruses preferentially bind human-like SAα2,6Gal receptor, a key prerequisite for infecting human cells.
G4 EA h2N1 Viruses Replicate Efficiently in Human Airway Epithelial Cells.
Next, we assessed the replication of G4 viruses in normal human bronchial epithelial (NHBE) cells and alveolar epithelial (A549) cells, the major target cells in human influenza virus infection. In NHBE cells, G4 and pdm/09 viruses replicated to similar levels at each time point, and both of them produced more viable progeny viruses during 36 h to 60 h postinfection (pi) than did G1 viruses (P < 0.05 or P < 0.01, ANOVA) (SI Appendix, Fig. S7A).
Infection of human A549 cells with G4 viruses gave similar progeny results. G4 and pdm/09 viruses produced more infectious virus than did G1 viruses from 24 h to 60 h pi (P < 0.05 or P < 0.01, ANOVA), reaching highest titers of 107.75 median tissue culture infective dose (TCID50)/mL and 107.5 TCID50/mL, respectively. In contrast, G1 viruses showed peak titers of 106.5 TCID50/mL (SI Appendix, Fig. S7B). Collectively, G4 EA reassortant viruses replicate efficiently in human airway epithelial cells, similarly to replication of pdm/09 h2N1 virus.
G4 EA h2N1 Viruses Exhibit Efficient Infectivity and Transmissibility in Ferrets.
Ferrets have been widely used as an experimental model to study human infection and transmission of influenza virus (27). Here, three ferrets were infected intranasally (i.n.) with each virus at a dose of 106 TCID50 in a 1.0-mL volume. We found that G1 EA or pdm/09 viruses caused only mild clinical signs (SI Appendix, Table S4). Infection with G4 EA viruses, on the other hand, resulted in more severe clinical symptoms such as pyrexia, sneezing, wheezing, and coughing, with higher mean maximum weight loss ranging from 7.3 to 9.8% (SI Appendix, Table S4). Postmortem and histopathology revealed that G4 virus-infected lungs had more-severe lesions than G1 or pdm/09 virus-infected lungs, with pronounced multifocal areas of consolidation, hemorrhage, and edema, and exhibited more severe peribronchiolitis and bronchopneumonia (SI Appendix, Fig. S8A). All four G4 viruses replicated to higher titers in the upper respiratory tract (nasal turbinate and trachea) of ferrets, which were similar to pdm/09 viruses and significantly higher than the two G1 viruses (P < 0.05 or P < 0.01, ANOVA), while no infectious virus was recovered from extrapulmonary tissues (SI Appendix, Fig. S8B). Overall, current G4 reassortant EA h2N1 viruses showed increased replication and pathogenicity in ferrets, indicating that G4 viruses are likely to cause more severe infection than G1 EA h2N1 viruses in humans.
Efficient human-to-human transmission is a critical feature of pandemic influenza viruses. To assess the transmissibility of G4 viruses, we performed direct contact (DC) and respiratory droplet (RD) virus transmission experiments on ferrets. The results showed that CA04 pdm/09 h2N1 virus efficiently transmitted to all ferrets by DC and RD (Fig. 3). All four G4 viruses were transmitted to all DC animals. Importantly, three of four G4 viruses, SW/SD/1207/16, SW/HN/SN13/18, and SW/JS/J004/18, were transmitted to all three RD ferrets. The remaining G4 virus, SW/HB/0116/17, was transmitted to one of three RD ferrets (Fig. 3). By contrast, with G1 viruses, neither virus transmission in DC or RD groups (Fig. 3) nor seroconversion at 14 day pi was detected in all recipient ferrets (SI Appendix, Table S4). Thus, there is compelling evidence to show that current predominant G4 reassortant EA h2N1 viruses are highly transmissible by DC and RD among ferrets, suggesting their capacity to readily infect humans.
Horizontal transmission of EA h2N1 viruses between ferrets. Groups of three ferrets were inoculated i.n. with 106 TCID50 of indicated viruses. The next day, infected animals were individually cohoused with an uninfected DC ferret; an uninfected RD contact animal was also housed in a wire frame cage adjacent to the infected ferret. Nasal washes for virus shedding detection were collected every other day from all animals from day 2 of the initial infection. Each color bar represents the virus titer of an individual animal. Dashed lines indicate the lower limit of virus detection.
G4 EA h2N1 Viruses Exhibit Low Antigenic Cross-Reactivity with Human Influenza Vaccine Strains.
Preexisting immunity can protect humans from related influenza viruses, but antigenic drift can decrease such protection in a population. Antigenic change is mainly due to variation of the HA gene. In this study, we found that the HA gene of EA h2N1 viruses isolated after 2013, including G4 viruses, formed an independent phylogenetic group. To determine the extent of antigenic drift of G4 viruses, 14 representative EA h2N1 viruses (10 G4 and 4 G1 viruses) were selected, based on their HA phylogenic topology, for antigenicity test.
A panel of ferret sera were used for hemagglutination inhibition (HI) assays, including sera against pdm/09 h2N1 virus A/Michigan/45/2015 from the current h2N1 human influenza vaccine lineage, G1 EA h2N1 viruses SW/HN/08/11 and SW/HB/T37/13, and G4 EA h2N1 viruses SW/SD/1207/16 and SW/HN/SN13/18. On the basis of reactivity levels in HI assays, EA viruses could be classified into antigenic groups A and B (Fig. 1B and SI Appendix, Table S5). The original G1 EA viruses were in antigenic group A, while G4 viruses belonged to antigenic group B. The cross-reactive titers between the two antigenic groups were 8- to 64-fold lower than those of homologous reactions. Antisera against pdm/09 h2N1 viruses (A/Michigan/45/2015) cross-reacted with antigenic group A viruses (titers 1:160 to 320) but reacted poorly with antigenic group B strains (titers ≤ 40) (SI Appendix, Table S5). Further analysis showed several amino acid differences in the HA antigenic sites among G1 and G4 EA h2N1 viruses, including 135 (h2 numbering) and 222 in Ca2, and 185 in Sb (SI Appendix, Table S6). However, which amino acid contributes to the observed antigenic change needs to be determined in future. Thus, predominant G4 reassortant EA h2N1 viruses are antigenically distinct from the earlier G1 EA and pdm/09 h2N1 viruses.
To assess cross-protection of human seasonal influenza vaccine against G4 EA viruses, HI assays were performed with 20 serum samples collected from 4-y-old children vaccinated with trivalent vaccines (pdm/09 h2N1+ h4N2 + B/Victoria). All serum samples were reactive (titers ≥ 1:40) to pdm/09 h2N1 and h4N2 viruses (Fig. 1C). However, none of the serum samples cross-reacted with the G4 or even the G1 EA h2N1 virus (Fig. 1C). Collectively, predominant G4 reassortant EA viruses are antigenically distinct from current human influenza vaccine strains, indicating that preexisting immunity derived from the present human seasonal influenza vaccines cannot provide protection against G4 viruses.
G4 EA h2N1 Viruses Showed Increased Infection Rate in Humans Evidenced by Seroprevalence.
To determine whether the G4 reassortant EA h2N1 virus can infect across species from swine to humans, serological surveillance was conducted to detect prevalence of virus exposure in swine production workers. From 2016 to 2018, a total of 338 serum samples were collected from swine workers in 15 farms. Serum samples (n = 230) from ordinary households were also collected as a population comparison group. G4 EA virus SW/SD/1207/16, which belonged to antigenic group B, was used as virus antigen in HI assays. To control for interference of h2N1 antibody against pdm/09 and earlier G1 EA viruses, pdm/09 virus A/Michigan/45/2015 and G1 EA virus SW/HN/08/11 were included as viral antigens. Disconcertingly, 10.4% (35/338) of swine workers and 4.4% (10/230) of general population were positive (titers ≥ 1:40) for G4 virus SW/SD/1207/16. In the multivariable analysis, after adjusting for confounders, swine workers had an increased odds ratio (aOR = 2. 60, 95% CI [1.24 to 5.45], P = 0.012) compared with the general population group. After controlling for possible cross-reactivity with pdm/09 virus, the odds ratio remained elevated (aOR = 2.25, 95% CI [1.05 to 4.83], P = 0.038) (Table 1). It is noted that swine workers in 4 of 15 farms were more than 15% seropositive against G4 virus SW/SD/1207/16 (SI Appendix, Table S7). In contrast, 6.5% (22/338) of swine workers and 2.2% (5/230) of the general population were positive for G1 virus SW/HN/08/11, with no statistically significant difference (P = 0.068) between the two groups after controlling for possible cross-reactivity with pdm/09 virus (Table 1). In addition, the swine workers group and general population were 38.8% (131/338) and 31.7% (73/230) seropositive, respectively, for pdm/09 h2N1 virus A/Michigan/45/2015 (P = 0.082). These results demonstrate that the newly prevalent G4 reassortant EA h2N1 viruses in pigs are more infectious to humans than their predecessors of G1 viruses.
Seropositive rate of influenza virus in swine workers (SW) and common household population (CHP)
We further investigated the association of sera collection year, age, or gender with seroprevalence of G4 reassortant EA h2N1 virus. In the swine workers group, the seropositive rates of G4 EA h2N1 virus were 6.7%, 11.7%, and 11.7% from 2016, 2017, and 2018, respectively (SI Appendix, Table S8). It is noteworthy that participants 18 y to 35 y of age had a 20.5% (9/44) seropositive rate against G4 EA h2N1 virus SW/SD/1207/16, which had an increased odds ratio (OR = 3.2, 95% CI [1.3 to 7.7], P < 0.01) compared with other age groups (SI Appendix, Table S8). For gender factor, no statistically significant difference in the seroprevalence of any virus tested according to sex was observed (P > 0.05). These results indicate that young adult swine workers carry a higher risk of infection with G4 reassortant EA h2N1 virus.
Pigs can independently facilitate the genesis of a human pandemic IAV strain (2, 7). Thus, continual systematic monitoring and assessing potential risks of emerging influenza viruses in pigs are necessary for early warning of future pandemics (28). In this study, based on extensive IAV surveillance in pigs from 2011 to 2018, we identified and characterized a predominant reassortant SIV (G4) derived from the reassortment of previous EA, pdm/09, and TR viruses. G4 h2N1 viruses are able to bind human-like SAα2,6Gal-linked receptor, replicate well in human airway epithelial cells, and transmit by aerosol among ferrets; they are antigenically distinct from pdm/09 h2N1 viruses. Of concern is that serological surveillance indicates the G4 reassortant EA h2N1 virus exhibits elevated infectivity in humans, especially for swine-exposed younger adults, which increases the opportunity for virus adaptation in humans.
EA h2N1 virus has been circulating in pigs in Europe and Asia for decades (29⇓–31). In 2001, EA virus was found in Hong Kong and gradually became dominant in mainland China (9⇓–11). Here, we also found that the “pure” EA h2N1 viruses of G1 were predominant in swine population from 2011 to 2013. However, since 2014, G4 and G5 reassortant EA h2N1 viruses gradually replaced the prototypical EA h2N1 viruses, and, currently, G4 viruses are the single predominant genotype circulating in China. Surveillance from farmed pigs with respiratory symptoms has shown that its isolation rate increased sharply after 2014, and increased year by year (SI Appendix, Fig. S2). Others have also reported on the infection of G4-like reassortant EA h2N1 viruses in farmed pigs (16, 18). A typical feature of G4 virus is that vRNP and M genes originate from pdm/09 virus, and NS gene is from TR virus, indicating that this gene constellation has a distinct competitive advantage in pigs. All of this evidence indicates that G4 EA h2N1 virus is a growing problem in pig farms, and the widespread circulation of G4 viruses in pigs inevitably increases their exposure to humans. So far, a total of five human cases of EA-like SIV infection have been reported in China (21⇓–23, 32, 33). The first three cases were children under 3 y old, but the latest two cases, reported in 2016 and 2019, were of a 46- and a 9-y-old, respectively. Genetic analysis indicated that the latter two cases were caused by G4-like EA h2N1 virus. Epidemiological survey found that the two patients had neighbors who reared pigs, suggesting that G4 EA virus could transmit from swine to human, and lead to severe infection and even death (22, 23). Thus, it is necessary to strengthen the surveillance effort of G4 EA viruses among swine and human populations.
Pandemic occurs when an IAV with novel HA surface antigen becomes readily able to undertake human-to-human transmission. G4 genotype of reassortant SIVs, identified in the present study, possesses all of the essential hallmarks of a candidate pandemic virus. G4 virus has different antigenicity from current human influenza viruses. Similar to pdm/09 virus, G4 virus preferentially binds human-like SAα2,6Gal receptor and effectively transmits in the ferret model. The G4 virus also shows increased pathogenicity, based on the present ferret study and other reports in mice (18, 34, 35). A limited serological investigation found that the general population, who had little opportunity to contact pigs, lacked antibodies against G4 virus, but swine-exposed adult populations showed elevated seroprevalence (10.4%, 35/338), which further supports our hypothesis of G4 virus transmission from pigs to human. It is of concern that human infection of G4 virus will further human adaptation and increase the risk of a human pandemic.
In summary, G4 EA h2N1 viruses possess all the essential hallmarks of being highly adapted to infect humans. Controlling the prevailing G4 EA h2N1 viruses in pigs and close monitoring of swine working populations should be promptly implemented.
As County Fairs Reopen, CDC Warns of Swine to Human Influenza Cases
The CDC recently announced the fifth human infection of influenza A virus subtypes that are commonly spread among pigs, occurring in 4 US states during the 20-21 (October 2020 through September 2021) influenza season. There is no evidence of subsequent person-to-person spread.
“These types of infections occur in people rarely, and usually in the context of exposure to pigs, but are concerning because of their pandemic potential,” the CDC report indicates.
The 5 reported infections of the 20-21 season occurred in Wisconsin (one h4N2v [v designating variant] and one h2N1v), North Carolina (one h2N1v), Ohio (one h2N2v), and Iowa (one h2N2v).
As this summer county fair season gets underway, the CDC advises avoiding the close proximity to pigs that can occur in pig barns and livestock exhibits; noting that infected pigs can cough or sneeze droplets with influenza virus.
Prevention measures recommended by the CDC include not eating or drinking in proximity to areas with pigs, avoiding contact with pigs that appear to be sick, and washing hands often with soap and running water before and after exposure to pigs.
Influenza viruses from different species can infect pigs, according to the CDC report, where virus can reassort, swapping genes to produce new strains that are a mix of swine, human, and/or avian influenza viruses.
“This is thought to have happened in 2009 when a new h2N1 virus with genes of avian, swine and human origin emerged to cause a flu pandemic,” the report notes.
In June of 2020, a surveillance study of swine influenza virus in China, published in the Proceedings of the National Academy of Sciences, described the emergence of a genotype 4 (G4) reassortant Eurasian avian-like (EA) h2N1 virus which bears 2009 pandemic (pdm/09) and triple-reassortant (TR)-derived internal genes. The investigators find this influenza A variant to have been the predominant subtype in swine populations in China since 2016.
Similar to the pdm/09 virus, the investigators indicate, the G4 viruses bind to human-type receptors, proliferate in human airway epithelial cells, and have shown efficient infectivity and aerosol transmission in animal (ferret) studies.
“Of concern is that swine workers show elevated seroprevalence for G4 virus,” the investigators observe.”Controlling the prevailing G4 EA h2N1 viruses in pigs and close monitoring in human populations, especially the workers in swine industry, should be urgently implemented. “
Since 2005, a total of 489 Influenza A virus variant subtype have been identified in the US, with some limited, non-sustained, person-to-person spread. Except for the 2009 h2N1 pandemic, there has not been ongoing community transmission. The CDC points out that seasonal flu vaccines are not formulated to protect against variant viruses; although the same influenza antiviral drugs used to treat seasonal flu can be effective against variant viruses.
“In general, the risk to the public from these infections is considered low, but each case of human infection with a variant influenza A virus should be fully investigated to be sure that such viruses are not spreading in an efficient and ongoing way in humans,” the CDC report advises.
90,000 Important Facts About Swine Flu – Questions and Answers
Swine Flu What is Swine Flu?
Swine flu is a respiratory disease of pigs caused by the influenza A virus and occasionally provokes outbreaks in animals. Swine influenza viruses cause high morbidity rates, with relatively low mortality rates, in pigs. They can spread among animals throughout the year, but more often outbreaks occur in late autumn and winter, similar to epidemics in humans.For the first time the classic swine flu virus (H1M1 influenza A virus) was detected in a pig in 1930
PIG FLU IN HUMAN
Can a person get swine flu?
Swine flu viruses are not normally transmitted to humans. However, there have been isolated cases of human infection with swine flu. Most often, the infection took place among people who had direct contact with animals (for example, children who were near pigs in the market, or workers on pig farms).In addition, there have been cases of human-to-human transmission of swine flu. For example, an outbreak of swine flu in animals in Wisconsin in 1988 caused numerous human diseases, but it did not cause an epidemic in the general population. However, the transmission of the virus from the patient to doctors who had close contact with him was confirmed by the presence of antibodies.
What are the symptoms of swine flu in humans?
Human symptoms of swine flu are thought to be the same as those of regular seasonal flu, and include fever, lethargy, lack of appetite, and cough.Some swine flu patients have reported runny nose, sore throat, nausea, vomiting, and diarrhea.
Can you get swine flu from pork?
No. The swine flu virus is not spread through food. You cannot get this virus by eating pork products. Properly processed and cooked pork products are safe. Cooking pork at an internal temperature of 7C will kill the swine flu virus as well as other germs and viruses.
How is swine flu transmitted?
Viruses of this disease can be transmitted directly from animals to humans and vice versa. People are most likely to become infected with swine flu when there is close contact with sick animals, for example, in a pig pen and at livestock shows for domestic pigs. Human-to-human transmission is also possible.
Presumably, the mode of infection is similar to the seasonal flu infection in humans, which is mainly carried out through coughing or sneezing of patients.A person can also become infected after touching an object on the surface of which there is respiratory secretions with the influenza virus, and then to their mouth or nose.
What medications are available to treat swine flu in humans?
According to WHO, there are four groups of antiviral drugs for the treatment of influenza: amantadine, rimantadine, oseltamivir and zanamivir. Although most swine influenza viruses are susceptible to all four drugs, recent WHO data suggest that the virus is resistant to amantadine and riman-tadine.
Swine flu in pigs How does swine flu spread among pigs?
Influenza viruses are believed to be transmitted through close contact between animals and, possibly, from infected objects that move between sick and uninfected pigs. Infected herds and herds vaccinated against influenza may experience occasional illness, moderate illness, or be asymptomatic.
What are the signs of swine flu in pigs?
Signs of swine flu in pigs include sudden onset of fever, depression, coughing (barking sounds), nasal and eye discharge, sneezing, difficulty breathing, redness or irritation of the eyes, and refusal to eat.
Is there a vaccine against swine flu?
Vaccines are available to prevent influenza in swine. But there are no vaccines to protect humans from swine flu.The seasonal flu vaccine is likely to help protect some of the H3N2 swine virus, but not H1N1.
A. OHANYAN, chief physician of Bagayevsky region
90,000 BBC Russian – Worldwide
Epidemiologists are looking for ways to contain the spread of swine flu.
What is swine flu?
Swine flu is a respiratory illness caused by influenza A, usually affecting pigs.
There are many varieties of this infection and it is constantly changing.
Until now, it has not passed to humans, but its last form has overcome the interspecies barrier and can spread from person to person, possibly by airborne droplets.
What’s new in this type of swine flu?
The World Health Organization (WHO) has confirmed that at least a few human cases have been caused by a h2N1 strain of influenza A, which is still unknown.
h2N1 is the same virus strain that causes regular seasonal outbreaks of influenza in humans.
However, the current variant of the h2N1 strain is different. It contains genetic material commonly found in viruses that infect humans, birds and pigs.
Influenza viruses are capable of exchanging genetic components. It seems that the new h2N1 variety appeared as a result of mixing different variants of viruses in the body of one animal, usually infecting representatives of different species.
Pigs are the ideal melting pot in which viruses can mix.
How dangerous is this disease?
Human symptoms of swine flu appear to be similar to those of normal flu.
These include fever, cough, sore throat, aches, chills and fatigue.
Of all the registered cases of the disease in the world, the majority of those infected have a mild form.However, in Mexico, several people have died.
How Serious Should You Take Swine Flu?
When a new strain of virus appears that can be transmitted from person to person, experts are watching it very closely, as it could potentially cause a global epidemic or pandemic.
WHO warned that cases of the disease in Mexico and the United States could cause a global pandemic, and indicates that the situation is very serious.
However, according to experts, it is too early to draw conclusions.
The world is now closer to an influenza pandemic, they point out, than at any time since 1968. Therefore, after an emergency meeting on Monday, the threat from the disease was raised from three to four on a six-point scale.
No one knows what the consequences of the pandemic might be, but experts have warned of the possibility of millions of deaths. The Spanish flu pandemic, or “Spanish flu”, which began in 1918 and was caused by the h2N1 virus strain, has claimed millions of lives.
The fact that the disease in those infected in the United States and in other countries has so far been mild is encouraging. It can be assumed that the severe course of the disease in Mexico may be caused by a specific geographic factor – possibly the presence of another virus in the population, which may not be present in other areas.
Another explanation may be the fact that people who fell ill in Mexico sought help at a later stage of the disease than those who fell ill in other countries.
It is also possible that the form of the virus found in Mexico is slightly different from that found elsewhere. But this can only be confirmed by laboratory analysis.
It is also hoped that because humans are often exposed to forms of the h2N1 virus during seasonal outbreaks of influenza, our immune systems can fight this infection more effectively.
However, it is very unusual that among those who died from the disease there are many young people.Typically, the elderly are most affected by the flu.
Can this virus be contained?
This virus, apparently, has already begun to spread around the world, and most experts believe that it is extremely difficult to stop its spread in an environment where people can travel freely around the world.
WHO officials argue that flight restrictions will not have the desired effect. Checking passengers arriving at airports, in their opinion, is also ineffective, since many infected people may not yet show symptoms.
Is swine flu treatable?
US authorities reported that two flu medications, Tamiflu and Relenza, appear to be effective in treatment. But you need to start using them at an early stage.
The use of these drugs reduces the likelihood of transmission of the virus from sick people to others.
The British government has already stockpiled large quantities of Tamiflu in case of a pandemic.
It is unclear how effective influenza vaccines will be in protecting against this new strain, as it is genetically different from other influenza strains.
American scientists are developing a completely new vaccine, but it will take time to develop and produce it in quantities that can meet the huge demand.
A vaccine was used in the United States in 1976 to protect humans against a type of swine flu.
However, she had serious side effects, including Guillain-Barré syndrome (in 500 cases). The vaccine has killed more people than the flu itself.
What to do to avoid getting sick?
People with flu symptoms who may have contracted the swine flu virus, such as those living in areas of Mexico experiencing an outbreak, should seek medical attention.
But the sick are asked not to go to the clinic in order to reduce the risk of the spread of the disease.They should stay at home and ask their doctor for advice over the phone.
After the WHO raised the threat of swine flu, the British Foreign Office issued a recommendation not to travel to Mexico, if it can be done without it.
What measures can be taken to avoid getting infected?
Avoid contact with people who look sick and who are coughing.
Generally accepted rules of behavior and hygiene help to reduce the spread of infection.So, you need to cover your mouth and nose when coughing and sneezing with a disposable napkin, which must then be thrown away.
It is also important to wash your hands with soap and water as often as possible and frequently wipe common items such as doorknobs and telephone handsets with a damp cloth.
Those caring for people with flu symptoms should cover their mouth and nose with a mask. In Britain, the authorities are planning to buy more of these protective masks for health workers.
But experts say there is no scientific evidence that wearing masks for prevention protects against infection.
Can I eat pork?
Yes. There is no evidence that a person can get swine flu if they eat meat from an infected animal.
However, it is very important to cook the meat thoroughly. The virus dies at 70C (158F).
The strain of avian influenza that has claimed dozens of lives in Southeast Asia in the past few years is different from the strain that caused the current outbreak of swine flu.
This is a new type of h2N1 strain, while avian influenza is caused by the H5N1 strain.
Experts believe H5N1 has the potential to cause a pandemic as it mutates rapidly.
However, until now, this disease remains mainly avian.
Without exception, all infected people have worked in close contact with birds, and cases of human-to-human transmission of the virus are extremely rare.There is no evidence that H5N1 has acquired the ability to pass easily from person to person.
Where can I get more information?
Information about swine flu and tips on how to protect yourself from it can be found on the websites of the world’s leading medical and research organizations.
90,000 What is important to know about swine flu? – Prevention
What is important to know about swine flu?
We heard about swine flu in 2009, when the world was in a panic amid news of the spread of its A / h2N1 virus, which caused the first swine flu pandemic in our century.In 2016, swine flu is the most active and dangerous of all existing forms of disease.
In order to understand the abbreviation of the virus, you need to know that influenza A is the most common type of influenza that causes the most large-scale epidemics, and h2N1 is a subtype of the influenza virus in pigs, which has highly pathogenic properties and the ability to be transmitted from person to person.
Currently, the epidemiological threshold has been exceeded in 47 regions of all federal districts, except for the Crimean one.By all criteria, the epidemic today can be considered moderate in intensity. The threshold was exceeded in the country as a whole – by 31.5 percent.
The main danger of swine flu lies in the ability of the strain to multiply not only in the upper respiratory tract (nasal cavity and larynx), but also in the lower (trachea and bronchi), and the multiplication of the A / h2N1 virus in the lower respiratory tract can lead to the development of viral pneumonia.
The danger of all influenza viruses is that they can mutate, so the vaccine has to be improved.The problem of the winter of 2016 is also that the usual seasonal flu has not disappeared, and A / h2N1 has reactivated. It should be borne in mind that the number of people affected by the swine flu does not exceed the number of people affected by seasonal influenza. In both cases, treatment must be started immediately in order to avoid serious consequences.
The difficulty lies in the fact that the symptoms of swine flu differ little from the symptoms of ordinary flu, and at the beginning they completely resemble the usual acute respiratory infections.However, unlike acute respiratory infections, the temperature jump occurs quickly, and it lasts for several days. When infected with swine flu, a person suffers from dry cough, high fever (39-40 degrees), drowsiness, general fatigue, sore throat, chest and muscles, lacrimation, lack of appetite. Less commonly, symptoms such as runny nose, photophobia, shortness of breath, nausea, etc. Swine flu can quickly develop into severe pneumonia.
The risk group includes various categories of people:
- People 30-67 years old suffering from diabetes, overweight, cardiovascular diseases, weakened immunity;
- Pregnant women;
- People over 67 years of age who are generally more susceptible to respiratory diseases;
- Children under 5 years old;
The World Health Organization, as well as the expert community, have developed some guidelines to follow during an influenza epidemic.
- Doctors recommend vaccinating, however, at the moment it is too late to do so. In the autumn in Russia, measures were taken to vaccinate the population from risk groups.
- Avoid crowded places. If this is not possible, wear a mask. Usually, a mask should be worn by people with cold symptoms if they are outside the home, but since this rule is not often followed, healthy people also need to protect themselves. The mask should be changed every two hours or more often, as it becomes damp and no longer protects against viruses and bacteria.
- Stay away from people who cough or sneeze.
- If possible, do not touch the handles and railings, do not touch your face after that.
- After coming from outside, wash your hands, face and even nose thoroughly with soap and water.
- Remember to wipe your phone and tablet with, for example, an antibacterial cloth.
- Stick to a healthy lifestyle, get enough sleep.
- In case of signs of malaise, a sharp deterioration in health, you should immediately consult a doctor.
- Take sick leave: the flu cannot be carried on your feet.
- Drink plenty of fluids, vitamin C.
- It is recommended to sneeze into the elbow rather than the palm.
It is categorically impossible to self-medicate. The doctor must prescribe drugs that not only relieve the symptoms of the disease, based on the characteristics of the patient, but also prescribe drugs that act specifically on the virus. In the case of influenza, medications are divided into:
- Symptomatic (our usual medicines that relieve headaches, runny nose, etc.)etc.)
- Virucidal preparations (disinfectants)
- Immunostimulants (including the group of interferon drugs)
- Etiotropic (affecting the virus)
It is necessary to start using drugs at the very beginning of the disease, this will give more chances for a speedy recovery and a mild course of the disease. Help in the fight against the disease and phytoncides – volatile plant secretions. Influenza viruses inhibit phytoncides in garlic, onions, eucalyptus and conifers.
New strain of swine flu discovered that could lead to a pandemic
Chinese scientists announced the discovery of a new strain of swine flu that can be transmitted from pigs to humans and can spread to pandemic proportions. A new strain called G4 is genetically linked to the h2N1 strain that caused the 2009 pandemic.
Researchers at the China Agricultural University, the China Center for Disease Control and Prevention and the University of Nottingham in the UK reported that they discovered a new h2N1 strain called G4 as a result of surveillance of the swine flu virus between 2011 and 2018.
The authors note that pigs should be considered as intermediate hosts or “mixing vessels” for pandemic influenza viruses.
“The G4 virus has all the basic features of a virus that could spread into a pandemic,” says a study published Monday in the journal PNAS.
Serological studies have shown that 10% of farm workers who have come into contact with pigs have antibodies to this strain. Most often they were detected in people aged 18 to 35 years.
Currently, the virus is transmitted from pigs to humans, and there is little evidence that the infection can now be transmitted from person to person. But scientists are concerned that the virus could mutate further, becoming much more contagious.
“Because pigs can be infected with influenza viruses from a variety of host organisms (such as birds and humans), they can serve as a” mixer “to help recombine influenza genes from different viruses and create a” new “influenza virus.The problem is that such a “new” reassortant virus could be more easily transmitted from person to person or could cause more severe disease in humans than the original viruses, ”according to the World Health Organization website.
According to the US Centers for Disease Control and Prevention, the 2009 swine flu outbreak claimed the lives of 157,000 to 575,000 people worldwide.
Eighty percent of deaths are estimated to have occurred in people under the age of 65.Almost a third of people over the age of 60 had antibodies, as they probably already encountered the h2N1 virus at a younger age.
A vaccine against this strain was developed in a short time, and in August 2010, WHO announced the end of the pandemic.
Doctor73 – News – What is the danger of “swine” flu was told by Olga Fadeeva, an infectious disease specialist of the Central Medical-Sanitary Unit named after V.A.A. Egorova Olga Fadeeva
“Swine” flu is a rather serious illness. We asked to answer the most frequently asked questions of residents about this disease.
– What is swine flu?
“Swine” flu, as it is popularly called, is an acute highly contagious infectious disease caused by the pandemic influenza A (h2N1) virus, transmitted from pigs and humans to humans, with a high susceptibility among the population with the development of a pandemic.It is characterized by fever, respiratory syndrome and severe course with the possibility of death. Today in medicine it is customary to distinguish several forms of this virus, but the most common are 3 of their subtypes, conventionally called A, B and C. The most dangerous subtype for humans is A.
– How to recognize swine flu? What are the symptoms?
The influenza A (h2N1) virus is easily transmitted from person to person and causes respiratory diseases of varying severity.The mechanism of action of this virus is similar to that of other strains of the influenza virus and the symptoms of the disease are similar to those of ordinary (seasonal) flu. The severity of the disease depends on a number of factors, including the general condition of the body and age.
The incubation period for swine flu lasts from 1 to 7 days. The clinical manifestations of infection are varied. In people with weakened immunity, the disease is very difficult and often ends in death.In some patients, on the contrary, it is asymptomatic and can be detected only when antibodies to the virus are detected in the blood serum (asymptomatic virus carrier).
In most cases, the signs of swine flu are similar to those of seasonal flu or SARS: intense headache, photophobia, fever up to 39-40 ° C, aching muscles and joints, weakness, lethargy, feeling weak, sensitivity to light, tickling and pain in throat, dry cough, runny nose, abdominal pain and diarrhea may join.
– How is the infection transmitted?
Transmission of infection is carried out by airborne droplets. The virus from the mucous membranes of the respiratory tract when breathing, sneezing, coughing, talking is released in huge concentration and can be suspended for several minutes.
The period of infectiousness (contagiousness) begins from the end of the incubation period and lasts the entire febrile period, reaching its maximum in 1-2 days after the onset of the disease. After 5-7 days of illness, the concentration of the virus in the exhaled air decreases sharply, and the patient becomes practically harmless to others.A great epidemic danger is posed by patients who, when sick with influenza, do not stay at home, but continue to visit public places. Continuing to lead an active lifestyle, they manage to infect a large number of people.
Influenza usually starts acutely. The incubation period is usually 1–2 days, but can last up to 5 days. Then the period of acute clinical manifestations begins. Swine flu can occur not only in a moderate and severe form, but also as a common ARVI.-
What complications can there be?
Complications after swine flu are manifested depending on a number of factors. The severity of the infection, the patient’s age, the person’s immunity, as well as the timeliness and effectiveness of medical care are important. Swine flu is more severe in elderly patients, as well as in children of primary school age, pregnant women, people with severe chronic diseases.
With proper and timely treatment of swine flu, the prognosis will be favorable.However, quite often this disease provokes a number of complications that can have a negative impact on the general state of human health. So, a frequent complication is the exacerbation of chronic diseases of the cardiovascular system. The latter is especially common in the elderly. Sometimes angina pain is also manifested, and in the first days of the disease, blood pressure rises. Also, in older people who suffer from chronic diseases of the respiratory system, mixed cardiovascular and respiratory failure may occur.Another serious complication of swine flu is sometimes acute pneumonia. Most of the acute pneumonias that occur as a complication of swine flu are of bacterial origin. Severe forms of pneumonia provoke pathogenic staphylococci, which are resistant to a large number of commonly used antibiotics.
– Why is swine flu dangerous? Is he really that aggressive and contagious?
With swine flu, a more severe course is observed, pneumonia may develop from 2-3 days.In the first 48 hours of illness, it is necessary to monitor the patient’s condition in order not to miss the development of complications. It should also be remembered that there are the most vulnerable groups of people – children, pregnant women, the elderly, people with chronic diseases of the heart, lungs, and immunodeficiencies.
– Are there medications for swine flu?
Treating a disease caused by strains of swine flu is essentially the same as treating so-called “seasonal” flu. Today, we have targeted antiviral drugs against the h2N1 influenza A virus.Self-medication for influenza is unacceptable, it is impossible to predict the course of influenza, with a severe form of influenza, various complications may develop. Therefore, it is necessary to prescribe specific antiviral agents and, if necessary, adequate therapy with antibacterial agents and other drugs (in order to prevent complications), additional examinations may be shown – chest x-ray, ECG.
Patients with influenza require constant monitoring by health workers, but, unfortunately, about 30% of patients are admitted to hospitals late – after 5-6 days of illness, which leads to a protracted course of pneumonia and other complications.
– What should be done in order not to get sick? What kind of prevention is there?
Realizing the danger of swine flu, you should take all measures to prevent the occurrence of this disease. The main measure for specific prevention of influenza is vaccination. It is carried out with effective influenza vaccines containing current strains of influenza viruses, including those for h2N1, recommended by the World Health Organization for the upcoming epidemic season, the composition of the vaccine is updated annually.Vaccination is recommended for all population groups, but primarily indicated for contingents from risk groups: children from 6 months, elderly people suffering from chronic diseases, medical workers, teachers, students, service workers, transport, pregnant women from the second trimester. Vaccination is carried out no later than 2-3 weeks before the onset of the epidemic rise in incidence.
It is also recommended to avoid contact with persons with signs of illness, reduce the time spent in crowded places and on public transport, wear a medical mask, regularly and thoroughly wash your hands with soap or wipe them with a special hand sanitizer, carry out wet cleaning, ventilation and humidification of air in the room.The viral particle of the influenza A virus has a diameter of about 100 nm, but it is not individual viral particles that fly in the air, but small droplets of liquid (fine aerosol) formed when sneezing. They settle in four to five hours, and a medical mask effectively detains them. Ultraviolet radiation effectively inactivates the virus; to inactivate the virus present in the air of the room, it is enough to irradiate the room with an ultraviolet lamp for half an hour. Airing the premises is useful, but you should not get carried away with cold drafts.
A correct way of life plays a significant role, it is good sleep, balanced nutrition, physical activity. The diet should include as many foods as possible containing vitamin C (lingonberries, currants, blueberries, citrus fruits, etc.). In order to increase the body’s resistance to respiratory viruses, including influenza viruses, as a measure of nonspecific prophylaxis, various drugs and agents that increase immunity (vitamin complexes) are used (on the recommendation of a doctor).
In conclusion, I would like to emphasize that the situation with influenza is generally typical for this period, traditionally January-February is the time of the rise of acute respiratory viral infections. The most important thing in this situation, if these symptoms occur, promptly seek medical help.
Chinese scientists have discovered a new strain of swine flu with “pandemic potential”
Chinese scientists studying swine flu viruses have announced the discovery of a new strain of this virus that can spread from pigs to humans and spread to pandemic proportions.As noted in a study published in the journal Proceedings of the National Academy of Sciences, the new strain is a combination of characteristics of the avian influenza strain found in birds in Europe and Asia, the h2N1 strain that caused the 2009 swine flu pandemic, and the North American h2N1 strain. , which contains the genes of avian, swine flu and the flu virus that people get sick.
According to the authors of the study, the new strain, called G4 EA h2N1, is quite capable of passing from pigs to humans and provoking a new pandemic.The study analyzed nearly 30,000 swabs taken from pigs in 10 Chinese provinces between 2011 and 2018 and found 179 swine flu viruses, most of which were G4. “The G4 virus has spread dramatically since 2016 and is the predominant genotype found in pigs in at least 10 provinces,” the scientists note. Influenza viruses are usually easily transmitted from pigs to humans, and two cases of human infection with the G4 virus have been documented, but an infected person rarely transmits the virus to another person.But scientists believe that the emergence of the new G4 virus characteristics of the h2N1 strain that led to the swine flu pandemic in 2009 could help the virus adapt, allowing it to spread from person to person.
However, there are other opinions. Commenting on the study by Chinese scientists in Science, evolutionary biologist at the John Fogarty International Center of the National Institutes of Health Martha Nelson said: “The likelihood that this particular option will provoke a pandemic is low.”There are too few analyzes analyzed to provide a detailed picture of which strains are prevalent in pigs in China, she said.
Rosselkhoznadzor assessed the danger of ASF spread
Rosselkhoznadzor assessed the risk of ASF spread
Rosselkhoznadzor assessed the risk of ASF spread News
The Rosselkhoznadzor assessed the danger of ASF spread
The spread of such dangerous diseases as avian influenza and African swine fever (ASF) in Southeast Asia, without adequate biological protection against viruses… RIA Novosti, 29.01.2020
The spread of coronavirus
Federal Service for Veterinary and Phytosanitary Surveillance (Rosselkhoznadzor )
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MOSCOW, January 29 – RIA Novosti. The spread of such dangerous diseases as avian influenza and African swine fever (ASF) in Southeast Asia, without proper biological protection against viruses, can lead to their mutation threatening humans, the press service of the Rosselkhoznadzor told reporters. ASF) does not pose a threat to humans, however, according to experts from the Federal Center for Animal Health, the possibility of its mutation cannot be ruled out. In addition, this level of a pandemic is already leading to serious economic and social consequences, threatening the population of domestic and wild pigs in all Asian region, “- said the press service.According to the department, the continuing spread of ASF in Europe demonstrates the low efficiency of measures taken to control the disease, as a result, this year the Rosselkhoznadzor expects the introduction of ASF to France, Germany. The department recalled that history knows many examples of changes in the genetic structure of viruses: for example, the influenza virus birds H5N6, which caused a serious infection in the population in 2016-2017, was a new strain resulting from the exchange of genes between four different viruses.In addition, in 2009, some strains of influenza virus subtype h2N1 (“swine flu”), acquired the ability to spread from person to person. Meanwhile, h2N1 has already caused influenza pandemics: in 1918-1919 from the so-called “Spanish flu” killed 40-50 million people. ASF was first recorded in 1903 in South Africa. It is a viral disease of domestic and wild pigs. The virus poses no threat to human health and other animal species, but threatens serious damage to pig breeding.In the event of a disease, the mortality rate is almost 100%. If a focus of infection appears, all pigs in the outbreak and within a radius of 20 kilometers from it are destroyed. The spread of the disease can only be stopped by strict quarantine measures.
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Federal Service for Veterinary and Phytosanitary Supervision (Rosselkhoznadzor), European Commission, European Union, Society
MOSCOW, January 29 – RIA Novosti. The spread of such dangerous diseases as avian influenza and African swine fever (ASF) in Southeast Asia, without proper biological protection against viruses, can lead to their mutation threatening humans, the press service of the Rosselkhoznadzor told reporters.
“Rosselkhoznadzor is concerned about the spread of dangerous highly contagious diseases in Southeast Asia, such as avian influenza and African swine fever.A high population density, a large population of agricultural and wild animals and birds, the development of farming, the joint keeping of different species in conditions that do not provide biological protection against viruses can lead to their mutation, “the press service said.
January 21, 2020, 15:47
Several cases of African swine fever were detected in the Samara region
“To date, the virus (ASF) does not pose a threat to humans, however, according to experts of the Federal Center for Animal Health, the possibility of its mutation cannot be ruled out.In addition, this level of the pandemic is already leading to serious economic and social consequences, threatening the population of domestic and wild pigs in the entire Asian region, “the press service said. control of the disease, as a result this year the Rosselkhoznadzor expects the introduction of ASF into France and Germany.
“Today it is known that one of the last outbreaks of ASF in Poland occurred among wild boars 12 kilometers from the border with Germany – such a distance is wild boars can overcome in a very short time.The European Commission is trying to preserve the status of large pork exporters for the EU countries, so it cannot be ruled out that the scale of the spread of ASF in the EU is already much wider than the officially declared ones, “the press service noted.
15 January 2020, 11:46
a new outbreak of African swine fever
The department recalled that history knows many examples of changes in the genetic structure of viruses: for example, the H5N6 avian influenza virus, which in 2016-2017 caused a serious infection in the population, was a new strain that arose as a result of gene exchange between four different viruses.In addition, in 2009, some strains of influenza virus subtype h2N1 (“swine flu”), acquired the ability to spread from person to person. Meanwhile, h2N1 has already caused influenza pandemics: in 1918-1919 from the so-called “Spanish flu” killed 40-50 million people.
ASF was first recorded in 1903 in South Africa. It is a viral disease of domestic and wild pigs. The virus poses no threat to human health and other animal species, but threatens serious damage to pig breeding.In the event of a disease, the mortality rate is almost 100%. If a focus of infection appears, all pigs in the outbreak and within a radius of 20 kilometers from it are destroyed.