Swine Flu and H1N1 Influenza

By Tammy Hunter, DVM; Krista Williams, BSc, DVM; Cheryl Yuill, DVM, MSc, CVH

What is swine flu?

Swine 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, variants of swine flu viruses have emerged, some of which have infected humans who have direct contact with infected pigs. In 2009 a new variant, H1N1, was identified. It was unusual because it could pass between humans. A strain of the H1N1 subtype is responsible for the 2009 influenza pandemic that caused illness in humans globally. To avoid misunderstanding about the source of this pandemic, authorities have recommended that it be referred to as H1N1 influenza.

If this is a flu of pigs, why do humans get it?

Usually, human cases of swine flu are uncommon and involve people who have close contact with pigs.

Genetic testing shows that the H1N1 strain is related to swine influenza virus strains but also contains genetic material from human and bird influenza strains. It is believed that a mixture of different influenza viruses that infect pigs shared or swapped their genetic information, leading to the development of the new strain of H1N1 that can infect humans.

Can dogs and cats catch the disease?

Since November 2009, several cases of H1N1 have been confirmed in cats and dogs in the United States. In all cases, it appears that pets were infected by direct transmission of the H1N1 virus from humans in the same household. Similar reports have been seen in different areas of the world including China and France. H1N1 appears to spread in cats and dogs similar to how it spreads in humans: direct contact or touching objects that have been contaminated by discharge from a sneezing or coughing patient. If you experience flu-like symptoms, it is recommended to take the same precautions with your pet as you would with other members of your family.

If your pet experiences flu-like symptoms or signs of an upper respiratory infection and you have recently experienced flu-like symptoms, 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 continue to closely monitor the spread of H1N1. Since the 2009 H1N1 pandemic, a very small number of infections have been identified in pig herds, and the virus was apparently spread to these herds by infected people. Pigs with flu symptoms should be isolated from other animals or people and be seen immediately by a veterinarian.

Can I catch it from pork products?

No, there is no evidence that touching uncooked pork could infect you.When handling any raw meat, you should always follow good food safety practices. These practices include washing your hands with soap and warm water before and after handling any raw meat; washing 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°F (71°C), you will kill any foodborne viruses and bacteria.

What about H1N1 spreading to or from other animal species?

Danish authorities have reported the emergence of another novel influenza virus in mink, and genetic sequencing demonstrated a new combination of human and swine genes. This finding further suggests that influenza 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?

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 that you immediately throw away.

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 should avoid visiting pig farms.

Where can I find the latest information on H1N1 influenza?

Find valuable and up-to-date information from health authorities:

  • Centers for Disease Control and Prevention (www.cdc.gov)
  • The Public Health Agency of Canada (www.canada.ca/en/public-health/)
  • World Health Organization (www.who.int)
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