On the Importance of Health Monitoring of Swine Workers

This is an article I wrote for a producers group newsletter on February 21, 2008. Unfortunately it was never published because the administrators of the newsletter thought it was too "controversial". I'm not sure what the controversy was. Perhaps it was the fact that I was advocating a review of their employee health policies or biosecurity protocols? Maybe they felt workers might be too scared to come to work? Who knows, but those were the facts and they remain salient today - although the anecdotes may be a bit dated. I ended up submitting piece on swine mange detection and control, which they found more agreeable. My original article follows:

I am sitting here at my computer, surrounded by NyQuil® capsules and
Kleenex®. I feel terrible but these flu symptoms are making me think
about a couple of recently published studies that focused on swine influenza
and its impact on swine workers.

A research group from the University of Alberta recently isolated a strain of Influenza A virus of probable swine origin (H3N2) from a 7-month old infant who lived on a communal farm in Canada. Another research group from the University of Iowa tested nearly 400 swine workers, including farmers, veterinarians, and
meat processing workers for exposure to strains of swine influenza. Their findings showed that occupational exposure to pigs greatly increases these workers' risk of
swine influenza virus infection. Why are these two studies important? It is well known that humans, pigs, and birds are linked in influenza transmission. During
the 1918 pandemic, a concurrent outbreak of swine influenza spread across the US Midwest. Numerous anecdotal accounts from that time period described flu-like illnesses developing in farmers and their families after contact with ill swine and of swine developing symptoms of swine influenza after contact with ill farmers. Since the 1918 pandemic, human influenza viruses have infected swine and swine influenza viruses have occasionally caused recognized disease among humans. The details of
the influenza virus are quite intricate however, it is important to know that Influenza A virus can infect people, pigs, and birds. Influenza A/H3N2 viruses occur commonly in humans; therefore most people have some antibody to these viruses. Two important swine flu virus strains are H1N1 and H3N2. H1N1 viruses do not commonly occur in people, however a high proportion of people occupationally exposed to pigs have been shown in several studies to have antibody evidence of prior swine H1N1 flu infection. For swine H1N1 viruses, only rare person to person
transmission has been documented in the past. Thus, human infections with swine H1N1 viruses should be investigated particularly when they are detected among non-occupationally exposed persons to ensure that human to human transmission is not occurring and to monitor for changes in circulating viruses and the emergence of novel viruses. Since the swine and human H3N2 viruses are similar, a swine H3N2
virus infection in humans would not represent a possible pandemic threat.

So what does this mean for the swine workers of today? Because of their potential bridging role in exposing humans to swine diseases, swine workers are an important risk group in a potential pandemic. Protecting swine workers from influenza viruses will also benefit those with whom they have contact, namely family members, as well as the swine herds for which they care. Encouraging swine workers to receive annual influenza vaccines will reduce their potential role in the genesis of novel influenza strains. You can read more about swine influenza and its importance in swine workers at the Centers for Disease Control and Prevention website: www.cdc.gov/flu/swine.

Heightened Biosecurity Measures

In light of the discovery of the circulating H1N1 influenza virus in a group of pigs on a farm in Alberta, now would be a great time for producers to review or initiate a clear biosecurity policy for their farms. Pigs are susceptible to many human flu viruses, therefore steps must be taken to minimize the introduction of a virus onto a farm, by people, by vehicles, and by wildlife such as birds, or other livestock.

The following are heightened biosecurity protocols that may be initiated during this outbreak:

• Ensure all biosecurity protocols are strictly followed
• People should avoid going into pig barns if they have influenza like symptoms (fever, sore throat, cough, runny nose, achy or tired) or if someone in their family has influenza like symptoms
• People who work in pig barns should visit their doctor if they develop influenza like symptoms
• Visitors should not be allowed into pig barns, especially if they have recently been to areas where people have been affected by this virus
• If symptoms of swine influenza occur in a herd (coughing, fever, depression, runny nose, off feed) contact your veterinarian promptly for diagnosis and advice.

The pork industry reminds the public that type A H1N1 influenza is not a food safety concern. People cannot catch type A H1N1 influenza from consuming pork or pork products and Canadian pork continues to be safe to eat.

H1N1 Diagnosed at Alberta Farm

A worrisome discovery was made when 220 pigs at a 2,200 head unit were diagnosed with the same strain of H1N1 currently spreading through the world's human population. It appears that a farm worker who had recently returned to work after a trip to Mexico may have been the point source for the infection. While it is common that humans can infect pigs and pigs can infect humans with so-called common strains of H3N2 influenza virus, this movement between species gives the virus an opportunity to mutate along the way. This may make it more likely for this virus to become more virulent although this is not a given. Another concern would be for the virus to become seeded in swine populations, especially on smaller farms that may not have the level of biosecurity as larger operations.

The herd has been quarantined and all pigs are recovering or have recovered. The farm worker has recovered as well. Read the story here: http://www.google.com/hostednews/canadianpress/article/ALeqM5jOCNS_KUIXJQ6YeBf31nkGFvTrNQ.