The Continuing Mystery of How Canadian Pigs Caught the Novel Flu Virus

On 2 May, a pig farm in Alberta, Canada, made international news when officials revealed that the animals there carried that novel H1N1 virus causing the swine flu outbreak in humans—the first and still the only pigs known to be infected. The Canadian Food Inspection Agency (CFIA) said it was “highly probable“that a Canadian who recently had traveled to Mexico and returned with flu-like symptoms had infected the pigs. At press conferences on 2 May and 7 May, Canadian officials explained that because the farmer did not buy pigs from other farms, the “contractor” who had gone to Mexico was the most likely source of the virus. That scenario ruled out the possibility that the pigs were infected before humans and may have held clues to the origin of the outbreak.

It turns out that the contractor, Adrian Blaak, was a carpenter who had worked on the farm for one day, 14 April, swapping out vents on a pig barn. Although Blaak was feeling ill that day, he had minimal direct contact with the pigs. The farmer first noticed illness in his pig herd on 24 April. Officials quickly suspected that Blaak was the source of the pig infection, but his symptoms had resolved by then, at which point it’s typically difficult to find the virus. Nasopharyngeal swabs taken from him, as expected, were negative for the novel H1N1. At a 7 May press conference, Frank Plummer, who heads the National Microbiology Laboratory in Winnipeg, a branch of the Public Health Agency of Canada (PHAC), said that they were going to test Blaak’s blood samples for antibodies to the novel H1N1 virus, which could confirm that he had been infected.  Plummer also discussed other workers at the farm who had flu-like symptoms and were being tested for evidence of infection with the swine flu virus.

ScienceInsider recently asked Plummer by email about the results from the tests of the carpenter’s sera. Plummer did not respond but his spokesperson on 3 June wrote that PHAC was “unable to answer questions related to specific cases.” The spokesperson suggested that the Province of Alberta might have more information, but the chief medical officer there also cited privacy reasons for not discussing the case.

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