It turns out birds have a flu season too.
After years of studying the role of wild birds in outbreaks of avian influenza in domestic poultry flocks, one of Canada’s top public sector veterinarians says the bottom line is farmers need to take precaution in the fall.
John Pasick is the national veterinary science authority for the Canadian Food Inspection Agency, and he says there’s an annual rhythm to infections. Much like humans tend to suffer more in the fall when kids return to the Petri dish of schools, birds spread disease in the fall during migration.
“The main message from our research is for farmers to maintain good biosecurity measures in the fall when the birds are migrating,” Pasick said in a recent interview. “Pay close attention to every detail during that time because domestic flocks have little natural immunity to diseases.”
Even when there is no direct contact between wild and farmed birds, the weather or even small rodents can spread diseases carried by wild birds into poultry, he said. In one case in Saskatchewan, pond water transmitted an infectious disease.
Pasick has worked as a veterinary virologist with CFIA and Agriculture Canada for 24 years, including 18 years at the National Centre for Foreign Animal Disease in Winnipeg. He was a World Organization for Animal Health Reference Laboratory expert for avian influenza and classical swine fever.
He recalls the outbreak of avian influenza in British Columbia in 2004. Coming on the heels of the BSE discovery in Alberta a year earlier, the poultry disease gained national attention. The disease has returned regularly since then, bringing it under scrutiny by Pasick and other experts.
Since then, researchers in Canada and elsewhere have been compiling data on disease outbreaks including questioning farmers whose flocks were affected. They also track migration patterns of wild birds. Their goal is to improve early warnings to farmers about disease threats.
One of their key findings is that breakdowns in biosecurity are a frequent contributor to the incident.
Basically what happens is a low-pathological disease in wild birds mutates into a high-pathological outbreak in farmed flocks kept indoors and often of the same age, he said. Backyard poultry flocks are less affected by diseases from wild birds because they are more diverse in age.
Every outbreak in Canada is closely studied to learn as much as possible about it and the overall threat to poultry farms, he said. Canada is working with the United States to better understand transmission patterns and what causes a low-pathological disease in the wild to become much deadlier in flocks.
It’s a global problem and waterfowl receive special attention in the study.
Several academic articles have been published detailing the problem in extensive detail.
Pasick is a contributor to a lengthy piece in the Scientific Reports series from the journal Nature on the outbreak of H5N2 in British Columbia in 2014.
Science Magazine, published by the American Association for the Advancement of Science, published a map showing how H5N8 spread from Southeast Asia through Russia into Europe and through Alaska into the Americas.