Wednesday, August 15, 2012
Study finds flu in healthy-looking pigs at state fairs
Lisa Schnirring and Robert Roos Staff Writers
Aug 15, 2012 (CIDRAP News) – Testing of a sampling of pigs shown at the Minnesota State Fair during the 2009 H1N1 influenza pandemic revealed that 19% of them were infected with flu viruses, even though they looked healthy, according to a new study.
The findings highlight the challenges of preventing pigs and humans from passing flu viruses back and forth at fairs and swine shows, especially this summer when several states are tracking human illnesses from a novel H3N2 virus that has been detected in both pigs and people.
The study, which appears today in Emerging Infectious Diseases (EID), was conducted by researchers from the University of Florida, University of Minnesota, South Dakota State University, and University of Iowa, along with scientists from the US Centers for Disease Control and Prevention (CDC).
With the goal of watching for influenza A viruses in show pigs, the group recruited people ages 7 and older who were showing pigs at the Minnesota State Fair in 2008 and 2009 and the South Dakota State Fair in 2009. Participants filled out a questionnaire and allowed the researchers to collect nasal swab samples from their pigs. Just over 70% of participants were male, and the median age was 34.9 years. About a quarter of the pig handlers were younger than 18.
They used the CDC's real-time reverse transcription polymerase chain reaction (rRT-PCR) tests to screen the samples for influenza A viruses. Blinded samples were sent to the Minnesota Veterinary Diagnostic Laboratory in St. Paul, where rRT-PCR testing for matrix, hemagglutinin, and neuraminidase genes was done, and specimens were sent to the National Veterinary Services Laboratory in Ames, Iowa, for molecular and genetic sequencing studies.
Specimens were collected from 149 pigs, including 47 and 57, respectively, from the Minnesota State Fair in 2008 and 2009 and 45 from the 2009 South Dakota State Fair. All of them were assessed as healthy by a veterinarian before they were cleared to enter their shows.
In 2008, investigators found no evidence of influenza A, but 12 (12%) of the 102 sampled collected in 2009 tested positive. These included 11 (19%) of the 57 samples from the 2009 Minnesota State...