A University of Alberta study recommends that workers on pig farms be monitored as part of influenza pandemic preparedness, after a child on a communal farm in Canada was diagnosed with swine flu in 2006.

Though the seven-month-old boy made a full recovery, health researchers were concerned because of evidence that the virus spread to other members of the multi-family community, who, fortunately, all demonstrated mild or no apparent illness. It has been known for a long time that avian and swine strains of flu can spread to humans, with avian strains appearing to be more dangerous than swine strains; as of late 2007, the avian flu had killed 194 people in 321 cases reported worldwide.

Of the 90 people on the farm tested by the University of Alberta and a team of other researchers with provincial and federal health agencies, 54 were tested for positivity to the swine flu strain.  Besides the baby boy, four of seven other household members and four of 46 other people living on the farm tested positive. The strain of flu was also detected in one of 10 young pigs on the farm. The child apparently had no direct contact with the swine.

“The concern is that swine viral strains could adapt into a form that results in efficient human-to-human transmission,” said Dr. Joan L. Robinson, a professor at the University of Alberta in Edmonton, Canada, a pediatrician at the Stollery Children’s Hospital, and lead author of the study, which was published recently in the journal Emerging Infectious Diseases. Swine flu in humans is “under-recognized in Canada, but it has the capacity to become a problem,” she added. “Early recognition that swine strains are becoming more virulent might expedite both implementation of ideal infection control precautions for symptomatic cases and vaccine development.”

Rather than workers on livestock farms being responsible for recognizing their own flu symptoms, there should be a public health program in place that leads to specific measures if an unexpected number or severity of cases of flu-like illness occur in swine workers.

No health program targeting swine workers currently exists, Robinson notes.