Late peak in influenza cases prompts call for continued focus on biosecurity

By Bruce Cochrane, Farmscape

The Western College of Veterinary Medicine is encouraging a continued focus on biosecurity on Canadian hog farms amid a later than normal peak in cases of influenza.

Typically, the number of cases of influenza in people and in pigs tend to peak in the fall in November-December and again in the late winter or early spring in February-March. By now, numbers would normally be on the decline.

Dr. Susan Detmer, an Associate Professor with the Western College of Veterinary Medicine, observed over the past month and a half Canada has been experiencing an upswing in influenza activity.

“We actually had very limited influenza activity for the 2020 and 2021 flu seasons. This was also true for the other respiratory pathogens such as the common cold. We attributed that to the lockdowns and all of the restrictions we had in place so there were less respiratory viruses going around entirely. Normally this time of year we're seeing it go down. Right now, the numbers are going up. It's a logarithmic increase so we don't know when it's going to peak out,” explained Dr. Detmer.

“We would expect that, as people go outside in the next few weeks, we'll start to see it decline again but it's hard to predict because the peak is coming so late in the year. Normally by mid-April we start to see a decline in influenza. Pre-pandemic, historically we see a decline in human influenza by the end of April and in pigs, because sometimes these viruses are going into pigs from people, we usually see a decline in that transmission by mid-May.”

 Dr. Detmer says we have very good biosecurity measures on hog farms in Canada and the United States.

She says pigs don't leave the farm but humans so do and so we need to be more concerned about whether the humans are protected properly to prevent zoonotic transmission of infections.

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