Oct 19, 2009 (CIDRAP News) – The US Department of Agriculture (USDA) today confirmed the pandemic H1N1 flu virus in a sample from a Minnesota pig, marking the first detection of the virus in pigs in the United States.
Suspected positive samples from pigs at the Minnesota State Fair were first reported by the USDA on Oct 16. The findings were confirmed by the USDA's National Veterinary Services Laboratories in Ames, Iowa, according to today's USDA press release. The release mentioned just one positive sample but said others were still being tested.
Agriculture Secretary Tom Vilsack said the USDA has reminded its trading partners that several international organizations emphasize that there is no scientific basis to restrict the trade of pork and pork products. "People cannot get this flu from eating pork or pork products. Pork is safe to eat," he said in the press release.
The USDA said that an infection in a show pig doesn't suggest that commercial herds are infected, because the two types of swine activities typically operate independently and don't involve the same personnel or animal stock.
The National Pork Producers Council (NPPC), in a statement today, reiterated that pork is safe to eat and handle and that the US Centers for Disease Control and Prevention (CDC) has said flu viruses can't be transmitted through food, including pork.
The sample that tested positive was collected at the Minnesota State Fair in August in a research project conducted by the University of Iowa and the University of Minnesota. The 2-year-old project, supported by the CDC, was designed to document flu viruses where humans and pigs interact, such as fairs and other exhibitions. The pig barn at the fair is a popular attraction, partly because the state's biggest pig is on display.
Three of 103 samples from pigs at the fair had come up positive in preliminary tests by the university researchers, the Minnesota Department of Agriculture reported on Oct 16.
Today's USDA announcement adds to the growing list of countries that have detected the pandemic virus in pigs. In early May, the virus was found for the first time in pigs in Alberta, Canada. Though an infected worker was thought to have spread the virus to the pigs, the connection was never confirmed. Other countries—such as Australia, Ireland, and most recently Norway—have more definitively linked infections in pig herds to infected workers.
The American Association of Swine Veterinarians (AASV) said on Oct 16 that several children who stayed in a Minnesota State Fair dormitory at the time the pigs were tested got sick with flulike illnesses and were went home, though there is no known link between the pigs and the children. A record number of people, about 1.8 million, attended the fair this year, though it is not known how many of them toured the swine barn.
According to CDC influenza surveillance reports, flu activity in Minnesota increased from sporadic to regional during the last part of August and into the first days of September when the state fair took place.
This summer some states announced extra measures to protect pigs from contracting the virus from sick fairgoers. For example, agriculture officials in North Carolina urged people to wash their hands before entering the fair exhibits to protect the pigs from the virus. They also asked sick people to avoid fairs and advised fair managers to add 6-foot barriers to separate animals from people.
The AASV recommends that swine workers receive seasonal and novel H1N1 vaccines and that producers observe good on-farm biosecurity. It also advises that producers continue immunizing their pigs against influenza, support the USDA's surveillance program, and submit samples when pigs show flu-like signs. It urges farmers not to ship sick animals to slaughter until clinical symptoms resolve.
The NPPC also renewed its plea for pork producers to tighten their biosecurity protocols to protect pigs from the virus, including restricting public access to barns.
Oct 19 USDA press release
Oct 19 NPPC press release
Oct 16 AASV statement
Oct 16 Minnesota Department of Agriculture release
Minnesota State Fair Web site