The science of oink
UF researcher detects swine flu strains at state fairs
By Jill Pease
Despite their healthy appearance, several pigs on show at two 2009 U.S. state fairs were infected with swine flu, according to a new study by UF infectious disease experts.
Up to one-fifth of show pigs at the 2009 Minnesota state fair were infected, and an infected animal was also found at the 2009 South Dakota fair, the researchers reported in the September issue of the Centers for Disease Control and Prevention’s Emerging Infectious Diseases journal.
The findings come in the wake of recent CDC warnings to fairgoers and reports of new swine flu strains, called H3N2 variants, in people who had direct or indirect contact with pigs at agricultural fairs.
“The new H3N2 variant viruses that are circulating now in pigs and apparently affecting people at pig shows are offsprings of the 2009 pandemic virus that spread throughout the world,” said lead investigator Gregory Gray, M.D., M.P.H., chair of the UF College of Public Health and Health Professions department of environmental and global health, and a member of UF’s Emerging Pathogens Institute. “It mixed with the viruses that were already present in pigs and out has come a new progeny virus.”
Between July 12 and Aug. 10, health authorities have confirmed 153 cases of H3N2 variant infections in four states.
For the 2009 study, Gray, then director of the University of Iowa’s Center for Emerging Infectious Diseases, and his team evaluated pigs and their handlers at the Minnesota and South Dakota state fairs. Of 57 pigs examined at the Minnesota fair, 11 tested positive for swine flu, and of 45 pigs examined at the South Dakota fair, one tested positive. In addition, six of seven viruses the researchers isolated from the pigs were identical to the pandemic H1N1 virus that had first been confirmed in humans just five months earlier, in April of that year.
“We really need a much better understanding of how common these infections are in U.S. pigs and how they are spreading,” Gray said. “Public health, veterinary health, environmental health and the pork industry must work closely together in understanding influenza transmission, as some of these viruses can cause significant health problems in man and pigs, as well as major economic harm to agribusinesses.”