How does swine flu spread between pigs and humans. What are the key facts about H1N1 influenza. Can humans contract swine flu from pigs. Is there a vaccine available for swine influenza.

The Nature of Swine Influenza: A Comprehensive Overview

Swine influenza, commonly known as swine flu, is a respiratory illness that primarily affects pigs. Caused by type A influenza viruses, this disease can lead to high morbidity rates among pig populations, although mortality rates tend to be low. While swine flu is primarily a concern for the porcine community, its potential to affect humans has garnered significant attention in recent years.

Characteristics of Swine Flu Viruses

Swine flu viruses are categorized into subtypes based on two surface antigens:

• Hemagglutinin (H)
• Neuraminidase (N)

These antigens play a crucial role in the virus’s ability to infect host cells and spread. Like all influenza viruses, swine flu strains are known for their constant mutations, which can lead to the emergence of new variants.

Current Swine Flu Subtypes

At present, four main influenza type A virus subtypes have been identified in pigs:

1. H1N1
2. H1N2
3. H3N2
4. H3N1

Among these, H3N2 and H1N1 have been the most frequently isolated strains in recent years.

The Prevalence of Swine Flu in Pig Populations

Swine flu outbreaks among pigs typically occur during late fall and winter months. The introduction of new pigs into existing herds can also trigger outbreaks. Studies conducted in the United States have revealed that a significant portion of the pig population shows evidence of past H1N1 infection.

Antibody Prevalence in Pigs

Research indicates that between 30% and 51% of the pig population in the United States has antibodies to H1N1. However, it’s important to note that the presence of antibodies doesn’t necessarily indicate a current infection. These antibodies can result from either vaccination or natural infection.

Can we distinguish between antibodies produced by vaccination and those from natural infection? Unfortunately, current methods do not allow for such differentiation in pigs. This limitation poses challenges for accurately assessing the true prevalence of natural swine flu infections in pig populations.

The Zoonotic Potential: Swine Flu Transmission to Humans

While swine flu viruses primarily infect pigs, rare cases of human infection have been documented. This zoonotic potential of swine flu viruses has been a subject of significant concern and research in recent years.

Frequency of Human Infections

How often do humans contract swine flu? The Centers for Disease Control and Prevention (CDC) reports receiving, on average, about one human influenza virus isolate that tests positive for swine flu each year. These cases most commonly occur in individuals who have had direct exposure to pigs.

Human-to-Human Transmission

While rare, there have been documented cases of person-to-person transmission of swine flu. One notable incident occurred in Wisconsin in 1988, where an outbreak of apparent swine flu infection in pigs led to multiple human infections. Although no community outbreak resulted, there was antibody evidence suggesting virus transmission from an infected patient to healthcare workers who had close contact with the patient.

Mechanisms of Swine Flu Transmission

Understanding how swine flu spreads is crucial for developing effective prevention and control strategies. The transmission mechanisms differ between pig-to-pig, pig-to-human, and human-to-human interactions.

Pig-to-Pig Transmission

In pig populations, the swine flu virus primarily spreads through contact with infected mucous secretions. Pigs infected with influenza virus typically exhibit symptoms such as:

• Runny nose
• Lethargy
• Cough
• Decreased appetite

When pigs are severely ill, their mucous carries high levels of the virus, facilitating transmission to other pigs in close proximity.

Pig-to-Human Transmission

Certain strains of swine flu virus can be directly transmissible to humans. Most human infections have occurred following direct contact with infected pigs. This highlights the importance of proper biosecurity measures for individuals working closely with swine, particularly in agricultural or veterinary settings.

Human-to-Human Transmission

While less common, human-to-human transmission of swine flu has been documented. This mode of transmission is particularly concerning from a public health perspective, as it raises the potential for wider community spread.

Historical Swine Flu Outbreaks: Lessons from the Past

Examining past swine flu outbreaks provides valuable insights into the virus’s behavior and potential impact on human populations. One of the most well-known incidents occurred in 1976 at Fort Dix, New Jersey.

The Fort Dix Outbreak

What made the Fort Dix outbreak significant? This event involved an outbreak of swine flu among soldiers, resulting in:

• At least four cases of disease with pneumonia
• One death
• All affected patients were previously healthy

The virus was transmitted to close contacts within the basic training environment, with limited transmission outside this group. It is believed to have circulated for approximately one month before disappearing.

Unanswered Questions

Despite extensive research, several aspects of the Fort Dix outbreak remain unclear:

• The source of the virus
• The exact time of its introduction into Fort Dix
• Factors limiting its spread and duration

Some experts suggest that the Fort Dix outbreak may have been an anomaly caused by the introduction of an animal virus into a stressed human population living in close contact under crowded conditions during winter.

Distinguishing Swine Flu from Human Influenza Strains

A common question that arises is whether the H1N1 swine flu virus is the same as human H1N1 viruses. The answer is no. H1N1 swine flu viruses are antigenically very different from human H1N1 viruses.

Antigenic Differences

What are antigens, and why are they important in this context? Antigens are substances that trigger an immune response in the body. In the case of influenza viruses, the surface proteins (hemagglutinin and neuraminidase) serve as antigens.

The antigenic differences between swine and human H1N1 viruses mean that:

• Immunity to human H1N1 strains may not protect against swine H1N1
• Vaccines developed for human H1N1 may not be effective against swine H1N1
• Diagnostic tests may need to be specific to differentiate between the strains

Prevention and Control: Vaccines for Swine Influenza

In the fight against swine flu, vaccines play a crucial role, particularly in pig populations. Are there vaccines available for swine flu? Yes, vaccines are available and are regularly administered to pigs to prevent swine influenza.

Vaccination in Pig Populations

Vaccinating pigs against swine flu offers several benefits:

• Reduces the incidence of illness in pig herds
• Minimizes economic losses for pig farmers
• Potentially reduces the risk of zoonotic transmission to humans

However, it’s important to note that, like all influenza vaccines, swine flu vaccines must be updated regularly to account for the constantly evolving nature of the virus.

Human Vaccines

While vaccines specifically for swine flu in humans are not routinely available, seasonal flu vaccines often include protection against swine-origin H1N1 strains that have adapted to circulate in human populations. During the 2009 H1N1 pandemic, a specific vaccine was developed and distributed to combat the outbreak.

Public Health Implications and Future Considerations

The potential for swine flu viruses to cause human infections and, in rare cases, human-to-human transmission, underscores the importance of ongoing surveillance and research in this area.

One Health Approach

Addressing the challenges posed by swine flu requires a One Health approach, which recognizes the interconnectedness of human, animal, and environmental health. This approach involves:

• Collaboration between veterinary and human health professionals
• Ongoing surveillance of influenza viruses in pig populations
• Rapid response mechanisms for potential outbreaks
• Research into cross-species transmission and virus evolution

Future Research Directions

Several key areas require further investigation to enhance our understanding and management of swine flu:

1. Improved diagnostics to differentiate between vaccine-induced and natural infection antibodies in pigs
2. Development of universal influenza vaccines that could protect against a wider range of strains
3. Better understanding of the factors that enable cross-species transmission
4. Enhanced surveillance systems to detect novel influenza strains early

By continuing to study swine flu and its potential impact on both animal and human populations, we can better prepare for and respond to future influenza threats. The lessons learned from past outbreaks, combined with ongoing research and surveillance efforts, will be crucial in mitigating the risks associated with this zoonotic disease.

As our understanding of swine flu continues to evolve, it’s clear that a multidisciplinary approach involving virologists, epidemiologists, veterinarians, and public health professionals will be essential in addressing the challenges posed by this and other emerging infectious diseases. By remaining vigilant and proactive in our approach to swine flu, we can work towards minimizing its impact on both animal and human health in the years to come.

Influenza

QUESTIONS & ANSWERS

Key Facts About Swine Influenza (Swine Flu)

What is swine influenza?

Swine influenza (swine flu) is a respiratory disease of pigs caused by type A influenza virus. Swine flu viruses cause high levels of illness and low death rates among pigs.
Swine influenza viruses may circulate in swine, including swine in Illinois.

Biology of swine influenza virus

Influenza A viruses in swine are categorized into subtypes based on two viral surface
antigens called hemagglutinin (H) and neuraminidase (N). Like all influenza viruses,
swine flu viruses change constantly. Pigs can be infected by avian influenza and
human influenza viruses as well as swine flu viruses. When influenza viruses from
different species infect pigs, the viruses can reassort (i. e. swap genes) and new viruses
that are a mix of swine, human and/or avian influenza viruses can emerge. Over the
years, different variations of swine flu viruses have emerged. At this time, there are four
main influenza type A virus subtypes that have been isolated in pigs: h2N1, h2N2,
h4N2 and h4N1. However, most of the recently isolated influenza viruses from pigs
have been h4N2 and h2N1 viruses.

How common is swine flu among pigs?

Outbreaks among pigs normally occur in late fall and winter and sometimes with the introduction of new pigs into herds. In the United States, studies have shown that 30 percent to 51 percent of the pig population has antibody evidence of having had
h2N1 infection. Antibody can be due to vaccination of pigs for swine flu or from natural
infection with swine flu. There is currently no way to differentiate antibody produced in
response to vaccination in pigs from antibody made in response to natural infection with h2N1.

Can humans catch swine flu?

Swine flu viruses do not normally infect humans. However, rare human infections with
swine flu have occurred. In the past several years, CDC has received, on average,
about one influenza virus isolate from a human that tests positive for swine flu each
year. Most commonly, these cases occur in persons with direct exposure to pigs. In
addition, there have been rare documented cases of one person spreading swine flu to others. For example, an outbreak of apparent swine flu infection in pigs in Wisconsin
in 1988 resulted in multiple human infections, and, although no community outbreak
resulted, there was antibody evidence of virus transmission from the patient to health
care workers who had close contact with the patient.

How does swine flu spread?

Pigs infected with influenza virus have a runny nose, lethargy, cough and decreased
appetite. The virus likely spreads from pig to pig through contact with infected mucous
secretions. (When pigs are really sick, their mucous carries high levels of virus).
Strains of swine flu virus also can be directly transmissible to humans. Most human
infections occurred following direct contact with infected pigs. However, there has been
at least one documented case of human-to-human transmission of swine flu.

What examples of swine flu outbreaks are there?

Probably most well-known is an outbreak of swine flu among soldiers in Fort Dix, New
Jersey, in 1976. The virus caused disease with pneumonia in at least four soldiers and
one death; all of these patients had previously been healthy. The virus was transmitted
to close contacts in a basic training environment, with limited transmission outside the
basic training group. The virus is thought to have circulated for a month and
disappeared. The source of the virus, the exact time of its introduction into Fort Dix, and
factors limiting its spread and duration are unknown. The Fort Dix outbreak may have
been an animal anomaly caused by introduction of an animal virus into a stressed
human population in close contact in crowded facilities during the winter.

Is the h2N1 swine flu virus the same as human h2N1 viruses?

No. The h2N1 swine flu viruses are antigenically very different from human

h2N1 viruses.

Is there a vaccine for swine flu?

Vaccines are available to be given to pigs to prevent swine influenza. There is no
vaccine to protect humans from swine flu. The seasonal influenza vaccine will likely
help provide partial protection against swine h4N2, but not swine h2N1 viruses.

What are the public health implications of human infections with swine influenza
viruses?

Human infections with animal influenza A viruses against which the human population
has little immunity should be investigated to determine the source of infection, and the
extent of spread and evidence of human-to-human transmission. Influenza A viruses
new to the human population that are able to efficiently transmit from person to person
and cause illness may represent a pandemic threat.

Although immunity to swine h2N1 viruses is low in the human population, a
high proportion of persons occupationally exposed to pigs (such as pig farmers or pig
veterinarians) have been shown in several studies to have antibody evidence of prior
swine h2N1 flu infection. And, for swine h2N1 viruses, only rare person-to-person
transmission has been documented in the past. Thus, human infections with swine
h2N1 viruses should be investigated particularly when they are detected among nonoccupationally
exposed persons to ensure that human-to-human transmission is not
occurring and to monitor for changes in circulating viruses.
Because most persons have some antibody to influenza h4N2 viruses since h4N2
viruses occur commonly in humans and because the swine and human h4N2 viruses
are similar, swine h4N2 virus infections in humans would not represent a possible
pandemic threat.

Adapted from CDC’s “Key Facts about Swine Influenza (Swine Flu)”

Factsheet on swine influenza in humans and pigs

Epidemiological background

Evidence of person-to-person spread of swine-origin influenza viruses (SIVs) is very limited and most swine-to-human transmissions have been epidemiologically dead-end events, i.e. onward transmissions are very rare.  One known exception is the A(h2N1)pdm09 influenza virus. Although this virus is likely of swine origin, it has not (to date) been detected in pigs prior to its appearance in humans. This could simply reflect that, as mentioned above, there is an absence (or limited presence) of programmes of surveillance for SIVs in many parts of the world.

Human infections with swine influenza have been sporadically detected (or at least published in the literature) since the late 1950s. These findings usually occurred in people with direct and indirect exposure to pigs i.e. people working in pig farms, etc. Sporadic transmission events of swine influenza viruses to humans have been reported in Europe and are described in the monthly Communicable Threat Reports (CDTR) as well as in the annual epidemiological zoonotic influenza reports.

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.

There are sporadic reports of human infections with swine influenza viruses, mainly in people who had direct contact with infected pigs. Since swine influenza is not a foodborne illness, it is highly unlikely for humans to contract swine influenza through eating pork, as influenza viruses are often only found in pigs’ respiratory tracts and cannot be found in their meat. Transmission occurs through aerosol and close contact with infected pigs as well as through a contaminated environment.

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. The first known introduction of human influenza virus into swine populations occurred after the Spanish flu in 1918 and this lineage was called ‘classical swine’ h2N1 (or lineage 1A). This lineage is still present in pigs in the Americas and Asia, but has not been detected in European pigs in the last two decades.

The first significant outbreak of an avian A(h2N1) influenza virus lineage occurred in 1979 and led to the establishment of an ‘avian-like’ A(h2N1) virus lineage in European pigs. This virus, referred to as Eurasian avian-like 1C lineage, rapidly established itself in Europe and has continued to circulate in swine until the present day.

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 A(h2N2) influenza viruses were established in Europe with the reassortment of swine A(h4N2) viruses and a human-seasonal A(h2N1) virus (h2huN2) and to date are still circulating among European pig populations.

The emergence of the 2009 pandemic A(h2N1) virus (h2N1pdm09) was a result of a reassortment event between a North American ‘triple-reassortant (TRA)’ swine influenza virus and a European ‘avian-like’ A(h2N1) (h2avN1) (lineage 1A. 3.3.2/pdm[MV2] ). Since its introduction into the European swine population, it reassorted broadly with the circulating swine A(h2N1), A(h4N2), and A(h2N2) subtypes.

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

To date, the most common 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 different related reassortant genotypes.

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 landscape of circulating swine influenza viruses in the US is quite versatile, due to many reassortment events throughout the years. 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. The first TRA A(h4N2) influenza virus was introduced in the US in 1998, evolving further into defined phylogenetic clades over time, of which some are still dominant to the present day. As a result of further reassortment between the TRA A(h4N2) viruses and classical swine A(h2N1), new TRA A(h2N1) and A(h2N2) viruses were generated and are still present in the US.

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, which produce more than 50% of the worldwide swine population,

 seems to be the only world region frequently importing pigs (and potentially SIVs) from other continents. The classical swine A(h2N1) viruses were endemic until the 1990s, however European A(h2avN1), A(h4N2), and North American ‘triple reassortant’ lineage viruses were introduced as a result of swine imports from other continents.

Surveillance for swine influenza in European pigs

Swine influenza in pigs is not notifiable at the EU level and no routine surveillance in pig populations is in place. Indeed, worldwide structured surveillance is very weak as swine influenzas are not considered to be a major threat to animal health. Surveillance is dependent on individual national or supranational initiatives to analyse and adapt the available swine influenza vaccines.

The surveillance of influenza in pigs in numerous Member States was conducted in a coordinated way through a project called ESNIP3, which was funded by the European Commission (DG-Research) and ended in 2013. The COST Action project (CA21132) led by the European Swine Influenza Network (ESFLU) aims to broaden the scope of the previous ESNIP2 and ESNIP3 projects towards a One Health approach, with a focus on diagnostic protocols and management capabilities aiming to mitigate swine influenza.

Swine influenza is among the 10 priority zoonotic diseases for which surveillance strategies have been proposed by EFSA.

The 2009 pandemic influenza A(h2N1)

The A(h2N1)pdm09 influenza virus from 2009 contained genes from pig, bird and human influenza viruses, in a combination that had not been reported before  in any part of the world. Following the emergence of the 2009 pandemic, this virus was also isolated from pigs in multiple areas of the world (including Europe), and it is currently circulating in pigs in several European countries. The infections in swine were initially due to transmission from infected humans, and then subsequently spread through pig-to-pig transmission.

The pig as a mixing vessel theory

The ‘mixing vessel’ theory supports the hypothesis that swine infected with swine influenza virus could be dually infected with avian or human influenza A viruses, as most swine influenza viruses are reassortants with mixtures of human, avian and swine virus genes. Pigs’ ability to serve as a ‘mixing vessel’ depends on the presence of both human-adapted and avian-adapted receptor types in their respiratory tract.

The transmission of these reassortant viruses to humans could then result in the introduction of novel viruses into the human population. On rare occasions, the combination of avian, swine and human influenza virus genes could produce a potential source for a human pandemic strain. 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 derive 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.

Page last updated

14 Mar 2023

What you need to know about swine flu.

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What you need to know about swine flu.

What is h2N1 (swine flu)?
h2N1 (commonly known as “swine flu”) is a new influenza virus that causes illness in humans. This new virus was first detected in humans in the United States in April 2009. Other countries, including Mexico and Canada, are also reporting human cases of the new virus. This virus spreads from one person to another, probably in much the same way as regular seasonal flu.

Why is the new h2N1 virus sometimes called “swine flu”?
This virus was originally called “swine flu” because it was found in laboratory studies that many of the pathogens in this new virus were very similar to influenza viruses commonly seen in pigs in North America. However, further studies have shown that the detected virus differs in many ways from that which is spreading among North American pigs. It contains two genes from influenza viruses commonly found in pigs in Europe and Asia, as well as bird genes. Scientists call this virus the “quadruple reassortant.”

How did the new h2N1 flu spread in people in the US?
The first confirmed cases of human infection with the h2N1 influenza virus in the United States were in Southern California and near Guadalupe County, Texas. Since then, the virus has spread rapidly, with infections being reported from a growing number of states. An updated number of cases of confirmed h2N1 influenza infections in the United States is continuously posted on the Internet at http://www.cdc.gov/h2n1flu/investigation.htm. The Centers for Disease Control and Prevention is working with local and state health agencies to investigate the situation.

Is this new h2N1 virus infectious?
The CDC has determined that the new h2N1 virus is contagious and spreads from one person to another. However, at the moment there is no information on how easily this virus spreads between people.

What are the main signs and symptoms of this virus in humans?
The symptoms of the new h2N1 influenza virus are similar to those of the seasonal flu. These include high fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills, and feeling tired. Many of the infected patients also complained of diarrhea and vomiting. In addition, as with seasonal influenza, serious and even fatal cases have been recorded as a result of the disease caused by this virus.

How serious is the disease associated with the new h2N1 virus?
It is currently unknown how dangerous this virus will become to the general population. CDC staff review the medical records of patients infected with the virus to determine if there are any groups of people who are at particular risk of infection, serious illness, or hospitalization associated with the virus. During seasonal flu, there are certain populations that are at greater risk for serious complications. Among them are people over the age of 65, children under five, pregnant women, as well as people of any age suffering from chronic diseases. At present, it remains unclear whether certain groups of people are at serious risk of developing complications due to infection with the new virus. The CDC is also conducting laboratory tests to determine if any people have natural immunity to this virus based on their age.

How is the new h2N1 virus transmitted?
The transmission of the new h2N1 virus is believed to be identical to that of seasonal influenza. Influenza viruses are mainly transmitted from person to person during coughs or sneezes of sick people. Some people can get sick by touching objects that contain flu viruses and then touching their own mouth or nose.

How long does it take for this virus to spread from an infected person to other people?
The CDC currently believes that this virus has the same spreading properties as seasonal flu viruses. Studies of seasonal influenza have shown that a person can be contagious 1 day before symptoms appear and 7 days after the onset of the disease. Children, especially younger children, may be potential carriers of the virus for a longer period of time.

Can you get sick with the new h2N1 virus if you eat or cook pork?
No. h2N1 viruses are not foodborne. Infection with the new HIN1 virus through pork or pork products is not possible. Properly processed and cooked pork products are completely safe to consume.

Is there a risk of disease through drinking water?
Tap water treated with existing disinfection methods does not pose a particular risk of transmission of influenza viruses, while providing a high degree of protection against viruses. The susceptibility of the new h2N1 influenza virus to accepted drinking water treatment processes has not been studied. However, recent studies have shown that the level of free chlorine commonly used to purify drinking water is sufficient to inactivate the highly pathogenic H5N1 avian influenza. It is likely that other influenza viruses, such as the new h2N1, will also be inactivated by chlorine treatment. To date, there have been no documented cases of influenza caused by contaminated drinking water.

Can the novel h2N1 influenza virus be spread through water in swimming pools, spas, water parks, fountains and other treated water used for bathing and swimming?
Influenza viruses infect the human upper respiratory tract. There are no documented cases of influenza virus infection associated with water use. The susceptibility of the h2N1 influenza virus to chlorine and other disinfectants used in swimming pools, spas, water parks, fountains, and other treated water sources used for bathing and swimming has not been studied. However, recent studies have shown that CDC-recommended levels of free chlorine (1–3 ppm [mg/L] for swimming pools and 2–5 ppm for spas) are sufficient to disinfect avian virus. influenza A (H5N1). It is likely that other influenza viruses, such as the new h2N1, will also be disinfected with chlorine.

Can the h2N1 influenza virus be transmitted in and outside of bathing and swimming water?
Yes, pools of water used for bathing and swimming are no different from other public places. The modes of transmission of the new h2N1 virus are believed to be identical to those of the seasonal flu. Influenza viruses are mainly transmitted from one person to another during the coughing or sneezing of sick people. Some people can get sick by first touching objects that contain flu viruses and then touching their own mouth or nose.

How can you protect yourself from infection?
There is currently no vaccine to protect against infection with the novel
h2N1 virus. To prevent the spread of respiratory illnesses such as the flu, normal daily hygiene practices should be followed.
To protect your health, use the following measures:

• Cover your nose and mouth with a tissue when you cough or sneeze. Throw away the used tissue in the trash.
• Wash your hands thoroughly and often with soap and water, especially after coughing or sneezing. Alcohol-based hand sanitizers are also effective.
• Do not touch eyes, nose or mouth. The infection is transmitted in this way.
• Avoid close contact with sick people.
• If you are ill, stay home for 7 days after symptoms develop or until symptoms develop within 24 hours, whichever is longer. This is necessary to prevent infecting others and further spread of the virus.

Other important things you can do include:

• Follow public health guidelines for school closures, social distancing, and other flu isolation measures.
• Be prepared to stay at home for about a week if you suddenly become ill; some stock of over-the-counter medications, alcohol-based hand rubs, tissues, and other related items may come in handy to help eliminate the need to go out in public while you are sick and
  carrier of the infection.

What is the best way to avoid spreading the virus through coughing or sneezing?
If you are sick, limit contact with other people as much as possible. If you become ill, stay home for 7 days after symptoms develop or until symptoms develop within 24 hours, whichever is longer. Cover your mouth and nose with a tissue when you cough or sneeze. Throw used tissues in the trash can. Afterward, wash your hands after every bout of coughing or sneezing.

What is the best way to wash your hands to avoid getting the flu?
Washing your hands frequently will protect you from germs. Use soap or an alcohol-based hand rub to wash your hands. It is recommended to wash your hands – with soap and warm water – for at least 15-20 seconds. If soap and water are not available, disposable wipes soaked in alcohol-based hand rub or disinfectant gels can be used. They can be found in most supermarkets and pharmacies. When using the gel, rub it into your hands until completely dry. The gel does not require water to act; the alcohol it contains will kill the germs on your hands.

What to do if you get sick?
If you have flu-like symptoms after returning from (or being in contact with someone with h2N1 influenza) from countries that are not prone to influenza, including fever, body aches, a runny or stuffy nose, sore throat, nausea, vomiting, or diarrhea, stay at home and avoid contact with other people unless you need to seek medical attention. If you are seriously ill or especially susceptible to complications from the flu, contact your healthcare provider or seek medical attention. The health facility will determine if flu testing is needed or if treatment is needed right away.
If you become ill and have any of the following signs that your condition is getting worse, call your doctor right away.
In children, similar signs that require urgent medical attention may include:

• Rapid or labored breathing
• Blueness of the skin
• Refusal to drink enough
• Severe or persistent vomiting
• Non-awakening or no response
• So excited that the child resists being picked up
• Some relief from influenza symptoms, which then returned with fever and increased cough

In adults, symptoms that require immediate medical attention
may include the following:

• Shortness of breath or shortness of breath
• Pain or pressure in the chest or abdomen
• Sudden dizziness
• Confusion
• Severe or persistent vomiting
• Some relief from influenza symptoms, which then returned with fever and increased cough

Are there medicines to treat the new flu?
Yes. The CDC recommends the use of oseltamivir or zanamivir to treat and/or prevent infection with the novel h2N1 influenza virus. Antiviral drugs are prescription drugs (tablets, solutions, or inhalers) that are designed to treat the flu and stop viruses from multiplying in your body. If you get sick, antiviral medicines can slow down the progression of the illness and help you feel better sooner. In addition, they can prevent serious complications caused by the flu. During the current epidemic, the use of anti-influenza antiviral drugs for the treatment of serious influenza is a priority.

How long does the influenza virus remain active on objects (eg books and doorknobs)?
Studies have shown that the influenza virus is able to survive on surrounding objects with the possibility of infecting a person within 2-8 hours from the moment it hits the surface.

What kills the influenza virus?
Influenza virus is destroyed by high temperature (75-100°C). In addition, some chemical germicides, including chlorine, hydrogen peroxide, detergents (soap), iodophors (iodine-based antiseptics), and alcohol solutions, are effective against human influenza viruses when used at the appropriate concentration for a sufficient period of time. For example, alcohol-based hand rubs and gels can be used to clean hands. Gels must be rubbed into the hands until completely dry.

Which surfaces are more likely to be contaminated?
Viruses can be spread when a person touches objects they are on and then touches their eyes, nose or mouth. Viruses are airborne when an infected person sneezes or coughs.

How should household waste be handled to prevent the spread of the influenza virus?
To prevent the spread of influenza virus, it is recommended that tissues and other disposable items used by an infected person be thrown into the trash.
Wash hands with soap and water after using wipes.

How do I clean my home to prevent the spread of the flu virus?
To prevent the spread of the influenza virus, it is important to keep surfaces (especially bedside tables, bathrooms, kitchens, and children’s toys) clean by wiping them down with household disinfectants according to label directions.

How should linens, cutlery and dishes used by people infected with the influenza virus be handled?
It is not necessary to wash linen and cutlery and dishes belonging to the patient separately, but it is important to remember that these items should not be used by others without careful pretreatment. Linens (such as sheets and towels) should be washed using regular laundry soap and dried in a hot dryer. Do not carry dirty linen “in an armful” to the place of washing in order to prevent your own infection. After carrying dirty laundry, wash your hands with soap and water or wipe them with an alcohol-based hand rub. Feedback and Research

What epidemiological studies are being carried out in response to the current influenza outbreak?
Daily monitoring of the epidemic situation in the world on influenza h2N1. At airports, monitoring (with thermometry) is carried out over the health of citizens entering Russia from countries that are unfavorable for h2N1 influenza. When identifying persons with signs of the disease, they are hospitalized and laboratory examination is carried out to clarify the diagnosis.

Swine flu

What is swine flu?
Swine flu is a respiratory disease of pigs caused by the influenza A virus that periodically provokes outbreaks in animals. Swine influenza viruses cause high levels of morbidity, with relatively low mortality, 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. The classic swine flu virus (h2N1 influenza A virus) was first detected in a pig at 1930 year.

How many swine flu viruses are there?
Like all influenza viruses, the swine flu virus is characterized by constant variability. Pigs can become infected with avian or human flu viruses as well as with swine flu viruses. When infecting pigs, influenza viruses of different species can “regroup” (ie replace genes) and form new strains that are a combination of swine, human and/or avian influenza infections. Over the years, many different types of swine flu viruses have emerged. There are currently four major influenza A virus subtypes identified in pigs: h2N1, h2N2, h4N2 and h4N1. However, most recently identified swine influenza viruses belonged to the h2N1 subtype.

Human swine flu

Can humans get swine flu?
Swine flu viruses are not normally transmitted to humans. However, isolated cases of human infection with swine flu have been observed. Most often, infection occurred among people who had direct contact with animals (for example, children who were close to pigs in the market, or workers in pig farms). In addition, human-to-human transmission of swine flu has been documented. For example, the outbreak of swine flu in animals in Wisconsin at 1988 led to numerous diseases among people, but it did not cause an epidemic among the population. However, the transmission of the virus from the patient to the doctors who had close contact with him was confirmed by the presence of antibodies.

How common is swine flu infection in humans?
According to the CDC, one case of swine flu every 1-2 years is registered in the United States, from December 2005 to February 2009, 12 human cases of swine flu were recorded.

What are the symptoms of swine flu in humans?
Symptoms of swine flu in humans are expected to be the same as those of regular seasonal flu and include fever, lethargy, anorexia, and cough. Some swine flu patients have reported a runny nose, sore throat, nausea, vomiting, and diarrhea.

Is it possible to get swine flu through pork dishes?
No. The swine flu virus is not transmitted through food. You cannot contract this virus by eating pork products. Properly processed and cooked pork products are safe. Cooking pork at an internal temperature of 70°C kills the swine flu virus in the same way 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. Humans are most likely to be infected with swine flu when there is close contact with sick animals, such as in a pigsty and at domestic pig livestock shows. Human-to-human transmission is also possible.
Presumably, the mode of transmission is similar to that of seasonal influenza in humans, which is mainly transmitted through coughing or sneezing of patients. A person can also become infected after touching an object with respiratory secretions containing the flu virus on the surface, and then touching their mouth or nose.

What do we know about human-to-human transmission of swine flu?
In September 1988, a previously healthy 32-year-old pregnant woman was hospitalized with pneumonia and died 8 days later. The h2N1 swine flu virus has been identified. Four days before going to the hospital, the patient visited a provincial pig fair, where a flu-like disease was widespread among the animals.
Subsequent studies showed that 76% of exhibitors tested had swine flu antibodies, but no serious cases were found among this group. Additional research shows that one in three health care workers who came into contact with the patient had a moderate flu-like illness with antibodies that suggested swine flu infection.

How can a person be diagnosed with swine flu?
Diagnosis of swine influenza A infection usually requires collection of a respiratory sample within the first 4-5 days of illness (when the patient is most likely to transmit the virus). However, some people, especially children, can be contagious for 7 or more days. Detection of swine influenza A virus requires sending to specialized virological laboratories for laboratory analysis.

What medicines 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 flu viruses are susceptible to all four drugs, recent WHO data indicate that the virus is resistant to amantadine and rimantadine.

Are there any other examples of swine flu outbreaks?
The most famous case is an outbreak of swine flu among soldiers at the Fort Dix military base in New Jersey in 1976 year. The virus caused the illness of at least 4 soldiers (X-ray showed pneumonia) and 1 death. All patients were previously healthy. The virus was transmitted through close contact in a military training group for 1 month with limited transmission outside of it. The source of the virus, the exact time it entered Fort Dix, and the factors that limited its spread and duration are unknown. It is possible that the outbreak at Fort Dix was caused by a virus of animal origin during the winter period in a group of people who were in a tense state, had close contact and were in overcrowded premises. The swine influenza A virus found in a soldier at Fort Dix was named A/New Jersey/76 (Hsw1N1).

Swine flu in pigs

How is 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. Influenza-carrying herds and herds vaccinated against influenza may experience sporadic cases of illness, may show moderate disease, or be completely asymptomatic.

What are the symptoms of swine flu in pigs?
Signs of swine flu in pigs include: sudden onset of fever, depression, coughing (bellowing noises), discharge from the nose and eyes, sneezing, difficulty breathing, red or irritated eyes, and refusal to eat.

How common is swine flu in pigs?
h2N1 and h4N2 swine influenza viruses are endemic in pigs. Outbreaks usually occur during the colder months (late autumn and winter) and sometimes after new animals are introduced into susceptible herds. Studies have shown that h2N1 swine flu is common in pigs worldwide; 25% of animals produce antibodies, which confirms infection. In the US, studies have found that antibodies that are indicative of h2N1 infection were detected in 30% of pigs. In particular, 51% of animals in the northern and central United States showed the presence of antibodies as evidence of infection with the h2N1 virus. Cases of human infection with the h2N1 swine flu virus are rare.
There is currently no way to distinguish between antibodies that are produced in pigs in response to influenza vaccine from antibodies that are produced in animals in response to infection with h2N1 swine flu. Since at least 1930, it has been known that the h2N1 virus is common among pigs. Initially, h4N2 viruses came to animals from humans. The active h4N2 swine influenza viruses are closely related to the human h4N2 viruses.

Is there a swine flu vaccine?
Vaccines to prevent influenza in humans have been developed and have already been received by the Kirishi Central District Hospital. In the coming days, vaccination of the adult population will begin, primarily those at risk of infection and transmission of the disease.

Symptoms and signs of swine flu, how to treat, how to avoid

Since mid-November, talks about the outbreak of swine flu A (h2N1) have not subsided in Russia. The new strain of the familiar virus has not yet taken the form of an epidemic, but is spreading rapidly: cases of infection have already been noted in 74 regions, although there were 55 a week ago. Izvestia found out the main symptoms of swine flu and the categories of people who are at risk.

In what regions of Russia swine flu was found

Against the backdrop of an increase in the incidence of SARS and influenza, the regions are once again introducing additional preventive measures, and Russians are buying masks and folk remedies for colds. Swine flu was the cause of a pandemic in 2009 and still circulates in the country as a seasonal flu, posing a significant threat to human health. Rospotrebnadzor acknowledges that the situation with the virus in some regions is tense. The epidemiological threshold has been exceeded in Moscow and almost reached in St. Petersburg, Yekaterinburg, Saratov, Kemerovo, Vladivostok, Kursk, Orenburg and other large cities.

Photo: Izvestia/Dmitry Korotaev

Russian Health Minister Mikhail Murashko urged Russians to wear masks in public places to stop the spread of the virus. However, experts interviewed by Izvestia are sure that it will not be possible to stop the flu so easily and that the peak is still far away. The maximum number of infections, according to forecasts, will occur during the New Year holidays and mid-January.

Swine flu symptoms:

list

As Natalya Ochinskaya, an infectious disease specialist at the SM Clinic, explained to Izvestia, the symptoms of swine flu and coronavirus are very difficult to distinguish. Infection occurs by airborne and household routes.

Signs of swine influenza A (h2N1):

1. Acute onset of the disease, the first symptoms occur within 12 hours.
2. High temperature – 39.5 degrees or more.
3. Head and muscle pain.
4. General intoxication of the body.
5. Dry cough that quickly becomes hacking and painful with the threat of turning into pneumonia.

Some patients also develop vomiting and eating disorders. To clarify the diagnosis and understand whether it is the flu or the coronavirus, a PCR test will help. This is important because the treatments for infections vary widely.

Complications after swine flu, who is at risk

As Vladimir Chulanov, chief freelance specialist of the Russian Ministry of Health for infectious diseases, specified, children under five years of age, adolescents from 15 years of age and elderly people over 65 are at risk for the incidence of influenza and SARS years, as well as pregnant women, employees of medical institutions and citizens with chronic diseases.

Photo: TASS/Alexander Ryumin

With swine flu, there is a high probability of a rapid development of pneumonia on the second or third day of illness. Therefore, at the first signs of this acute respiratory disease, it is necessary to consult a doctor and use antiviral drugs in order to block the activity of the virus in time. Other complications include hyperthermic and hypertoxic reactions, in rare cases damage to the central nervous system, and various vascular reactions. The RPN explained that a patient can become infected with two strains of influenza at once: similar cases have already been recorded in Russia, although there are not so many of them.

Mistakes in the treatment of swine flu and prevention

Airing rooms and cleaning smartphones will help reduce the risk of contracting influenza and SARS, but ginger, vitamin C and garlic have no evidence base for the prevention of viral diseases, doctors say. As a preventive measure, you can rinse your nose and gargle with saline solutions, Anna Simbirtseva, a general practitioner of the federal network Fomin’s Clinic, reminded Izvestia. Susceptibility to viral infections can be affected by deficiency or insufficiency of vitamin D and zinc – this point should be discussed with your doctor. As a general recommendation, doctors suggest less frequent visits to crowded places or wearing masks.

Photo: TASS/Mikhail Japaridze

One of the main mistakes is the late appeal to the doctors. When calling a doctor, experts recommend not delaying, as h2N1 swine flu can cause many complications and lead to hospitalization or even death. At the same time, the RPN states that the Russian healthcare system is fully prepared to receive a large number of patients with influenza.

Swine flu vaccine, worth it or not

Timely vaccination remains the main and reliable way to prevent swine flu and SARS. The head of Rospotrebnadzor emphasized that Russian flu vaccines protect against a severe course of the disease. One of them in the form of a spray from the Center. N.F. Gamaleya will protect against all types of virus. It is better to get vaccinated in late November – early December, because the body needs about two weeks to develop immunity.

Photo: Izvestiya/Sergey Konkov

According to the RPN, by the beginning of December, almost 50% of Russians had been vaccinated against the flu, that is, more than 72.4 million people had already been vaccinated in the country.