H1N1 Influenza and Pigs
by D. Van Metre * (12/14)
Revised by M. Eisenach**
- H1N1 influenza is a new strain of the influenza (or flu) virus that has been circulating among many people across the world since it was first detected in people in Mexico.
- The symptoms of H1N1 influenza in people overlap greatly with those of “seasonal influenza,” which typically occurs in people in the late fall and winter.
- It is important that pig owners understand that the H1N1 virus can be transmitted from people to pigs.
In the fall of 2009, human and animal health government agencies announced that the H1N1 virus had been detected in a pig in Minnesota. Colorado pig owners need to remind themselves of a few simple facts and principles that will help them to prevent infection in their pigs. First, it may be helpful to review some fundamental facts about H1N1.
1. What is H1N1 influenza?
H1N1 influenza is a new strain of the influenza (or flu) virus that has been circulating among many people across the world since it was first detected in April of 2009 in people in Mexico. It is also called “pandemic flu” because it is currently spreading in people worldwide – that’s what the term pandemic means. The H1N1 virus derived originally from a strain that lived in pigs, but it also contains the genes of influenza viruses of birds and humans. This origin gave rise to the common name of “swine flu”, widely used by mass media at the start of the H1N1 pandemic. Since then, the veterinary and medical professions, in conjunction with governmental health agencies, have recommended that the term H1N1 be used to describe this virus, to minimize confusion regarding terminology and the safety of eating pork.
The symptoms of H1N1 influenza in people overlap greatly with those of “seasonal influenza,” which typically occurs in people in the late fall and winter. The strains of flu involved in seasonal influenza are different from this newer H1N1 virus.
2. A pig in Minnesota tested positive for H1N1 influenza virus. What does this mean for pig owners?
It is important that pig owners understand that the H1N1 virus can be transmitted from people to pigs. Therefore, any person showing symptoms of the flu, such as fever, headache, runny nose, sore throat, or a cough should not come in contact with pigs. This is the most important step that a pig owner can take to protect their herd. At this time, there is no evidence that an infected pig can cause illness in people.
3. Other than keeping people with flu symptoms away from my pigs, what else can a pig owner do to keep his or her pigs from becoming infected?
If a pig owner takes a pig to a show or fair, the owner should request that signs be posted that ask people with symptoms of the flu to keep away from pigs.
Keep pigs that travel to shows or fairs isolated from the main herd for two weeks after returning from a fair or show, just in case a pig might have been exposed to someone with flu.
Maintaining good ventilation and overall hygiene in the pig barn will help the pigs stay healthy. Keeping their feed and water clean is also important for good general health.
People working with pigs should wash their hands before and after handling pigs, their feed, or their bedding. Ideally, people working with pigs should wear waterproof outer boots that can be disinfected with Lysol® after use. People working with pigs should wear coveralls or a dedicated set of working clothes when working with pigs. These clothes/coveralls and boots should be left at the entrance to the barn after use.
Limit visitors to the farm to only visitors whose visits are absolutely necessary, who are currently healthy, and who have not experienced flu-like symptoms themselves or in their families in the previous week.
As the H1N1 influenza and seasonal influenza vaccines become available, people who work with pigs should get vaccinated. A vaccine is being developed to protect pigs from H1N1 but is not yet commercially available.
4. If a pig were to become infected with H1N1, what signs would develop?
The symptoms of influenza in pigs are the same as they are in people – fever, congestion, coughing (the cough often sounds like a “bark”), sneezing, and aches. As for people, most pigs infected with influenza virus recover after a few days of illness.
If you are concerned about the possibility of infection in your pigs, contact your veterinarian. The steps to take are similar to those for people. A pig showing symptoms of flu should be isolated from other pigs, kept warm, dry, and comfortable, and offered plenty of good food and water.
5. If pigs become infected, can they transmit the infection to people?
At present, there is no evidence that pigs have transmitted the H1N1 virus back to people. People can transmit it to pigs, and infected pigs can transmit it to other pigs. This is why we should focus on keeping people with signs of flu away from our pigs.
However, people should take precautions to protect themselves if their pigs show symptoms of flu. Why? Many strains of the influenza virus exist, and, although examples are rare, some strains can potentially be transmitted from pigs to people. If your pigs are showing symptoms of flu, the precautions that you can take to protect yourself are:
1.) Wash your hands before and after handling pigs, their feed, or their bedding.
2.) Wear waterproof footwear when handling pigs, their feed, or their bedding. Disinfect this footwear with Lysol® after use, and keep footwear at the entrance to the pig barn between uses.
3.) Wear coveralls or outer clothing dedicated solely to being worn around pigs. This outer wear should also be left at the entrance to the pig barn between uses.
4.) Consult your physician or health care provider to determine if you are able to wear an “N95” mask to limit the chances that you might inhale the virus when working with pigs. These masks are available at most hardware stores.
5.) Young children, the elderly, and people with pre-existing respiratory or immune system disorders should not come in contact with pigs showing symptoms of flu.
6. Even if a pig were to become infected with H1N1 virus, would its pork be safe to eat?
Yes. The Centers for Disease Control (CDC) recently reiterated what veterinarians and pork producers have maintained since the virus emerged last spring. According to the CDC, H1N1 is not transmitted by food. You cannot get this flu from eating or handling pork or pork products. The same is true for other strains of the influenza virus – they cannot be transmitted by handling or eating pork or poultry. As has always been the case, pigs with symptoms of any existing illness should be allowed to recover before being sold at an auction or taken to slaughter – this is a common-sense principle that helps to keep our food supply the safest in the world.
7. Where can I find more information about influenza and its effect on pigs and people?
*D. Van Metre, DM, DACVIM, Colorado State University Extension specialist (veterinarian) and associate professor, College of Veterinary Medicine and Biomedical Sciences, Clinical Sciences. **M. Eisenach, Colorado State University Extension agent, livestock, Morgan County. 5/10. Revised 12/14.
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