Swine Flu and the 2009 H1N1 Influenza Virus Pandemic

What is Swine Flu?

swinefluSwine Influenza or swine flu is a contagious respiratory disease of pigs, caused by a type A influenza virus. Type A influenza viruses can affect a range of other animals and humans. Like all influenza viruses, swine flu viruses change or mutate constantly. Swine flu is commonly seen in North America, South America, Asia, and Europe.

What is the difference between Swine Flu and H1N1 Influenza?

Over the years, different variants of swine flu viruses have emerged, and at this time, 4 main influenza type A virus subtypes have been identified in pigs (H1N1, H1N2, H3N2 and H3N1). A strain of the H1N1 subtype is responsible for the 2009 Influenza Pandemic that is causing illness in humans on a global basis, and that is being spread mostly by human-to-human contact. To avoid misunderstanding about the source of this pandemic, authorities have recommended that it be referred to as H1N1 Influenza.

What is a Pandemic?

Pandemic influenza is defined as a new influenza virus that spreads easily between humans and affects a wide geographic area. Influenza pandemics have been observed for several hundred years. The best-documented pandemics occurred during the 20th century, in 1918 (Spanish influenza), 1957 (Asian influenza) and 1968 (Hong Kong influenza). These varied in severity, with an estimated 1-50 million excess deaths during the pandemics. However, just because the disease is classified as a pandemic, it does not necessarily mean that it causes more severe disease.

On April 29, 2009, the World Health Organization (WHO) verified human-to-human transmission of H1N1 Influenza, and raised its pandemic alert level to Phase 5. A Phase 5 alert is a "strong signal that a pandemic is imminent and that the time to finalize the organization, communication, and implementation of the planned mitigation measures is short."

On June 11, 2009, the pandemic alert level was raised to Phase 6, meaning that a pandemic had been confirmed and that "sustained community-level transmission of the virus is taking place in more than one region of the world".

"Just because the disease is classified as a pandemic, it does not necessarily mean that it causes more severe disease."

WHO is continuing to monitor the situation, report the statistics and coordinate the disease response. Over 200 countries have reported laboratory-confirmed cases of H1N1 influenza in the 2009 Pandemic.

If this is a flu of pigs, why are humans getting it?

Usually, human cases of swine flu are uncommon and involve people who have close contact with pigs. The 2009 pandemic H1N1 influenza began in Mexico in the early spring and is primarily being spread by contact between people. These cases involve a new strain of the H1N1 subtype.

Genetic testing shows that this strain is related to swine influenza virus strains but also contains genetic material from human and avian influenza strains. Because this is a new strain, people and animals will have limited natural immunity, so the virus can spread rapidly.

As the number of human cases rises, the pandemic will accelerate and the likelihood that the virus will be transmitted from humans to other animal species will increase. However, the isolated cases in animals will have little impact on the current pandemic, which is spreading readily via human-to-human transmission and the animal cases will pose no special risks to human health.

 "A case of H1N1 in a cat in Iowa, USA, was confirmed on November 2, 2009."

What are the symptoms in people?

H1N1 influenza has the same symptoms as regular human seasonal flu, with a mild and short-lived illness in most adults. Symptoms are similar in humans and animals and generally include fever, fatigue, loss of appetite, sore throat, coughing, sneezing, runny nose and congestion; occasionally, the patient may develop vomiting and diarrhea.

Although most people do recover from the illness without the need for hospitalization or medical care, it is capable of causing serious illness or death in some individuals. In adults and children, the majority of deaths have occurred in people with pre-existing serious disease. However, the infection has caused serious illness or death in children who were apparently healthy prior to becoming infected with H1N1.

How is H1N1 Influenza spread?

Like most respiratory viruses, H1N1 influenza is contagious and spreads via direct contact with an infected patient or by touching objects that have been contaminated by discharges from a sneezing or coughing patient.

Can dogs and cats catch the disease?

Since November 2009, several cases of H1N1 have been confirmed in cats in the United States. In all cases, it appears that the cats were infected by direct transmission of the H1N1 virus from humans in the same household. In December 2009, the virus was detected in 2 dogs in China and 1 in the United States.

If your pet is experiencing flu-like symptoms or signs of an upper respiratory infection, it would be wise to seek immediate veterinary care. As human infections become increasingly widespread, transmission of the virus from humans to other animals is likely to occur with greater frequency.

Are pigs catching and spreading the H1N1 virus?

Veterinarians and government agencies are closely monitoring this situation. Since the 2009 H1N1 pandemic emerged, a very small number of infections have been identified in pig herds, and the virus was apparently spread to these herds by infected persons. Pigs with flu symptoms should be isolated from other animals or people and be seen immediately by a veterinarian.

Can one catch it from pork products?

No. There is no evidence that touching uncooked pork could infect you.

As a general reminder, you should always follow good food safety practices when handling any raw meat. These practices include washing hands with warm water and soap both before and after handling any raw meat; wash the cutting board, knives, and countertops with hot, soapy water, and keeping unwrapped raw meat away from any cooked food.

The virus is killed at normal cooking temperatures. If you ensure that pork is cooked properly (not pink in the middle) to an internal temperature of 160° Fahrenheit or 71° Celsius, you will kill any foodborne viruses and bacteria.

What about H1N1 spreading to or from other animal species?

Since the new pandemic H1N1 2009 virus emerged, infections in different species of susceptible animals (pig, turkey, ferret, cat, and dog) have been reported. Limited evidence suggests that these cases in animals are the result of direct transmission from infected humans.

Danish authorities recently reported the emergence of another novel influenza A virus in mink, and genetic sequencing demonstrated a new combination of human and swine genes. This finding further suggests that Influenza A viruses in animals and humans increasingly behave like a pool of genes circulating among multiple hosts, and that the potential exists for novel influenza viruses to be generated in animals other than swine. This situation reinforces the need for close monitoring and close collaboration between public health and veterinary authorities.

How do we protect ourselves?

"Wash your hands frequently and practice good hygiene."

To minimize your chance of infection, wash your hands frequently and practice good hygiene. If you are ill, stay home to avoid spreading the virus, and sneeze or cough into a disposable tissue which you immediately throw away.

Evidence shows that the use of surgical masks by the general public is not effective in preventing transmission of influenza. For more information about the use of surgical masks for protection, please check the following link:


Any person experiencing severe flu-like symptoms should immediately contact their health care provider. Because humans can spread the disease to pigs, people showing symptoms of influenza, especially those who have recently returned from travel to Mexico or other affected areas should avoid visiting pig farms.

 How do I keep up to date?

The World Health Organization is collaborating with the governments of countries with confirmed cases of swine influenza and will continue to issue updates as new cases occur. For accurate and up-to-date information, go to:

www.cdc.gov/swineflu/  (Centers for Disease Control)

www.phac-aspc.gc.ca  (The Public Health Agency of Canada)

www.who.int/csr/disease/swineflu/en/index.html  (World Health Organization)

Related Tags

swine, influenza, virus, h1n1, pandemic, pigs, mexico, swineflu, swine flu,

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