H5N1 Avian Flu Viruses Found in Manitoba, but Not Asian Form of Virus: CFIA

By HELEN BRANSWELL

TORONTO (CP) – Two wild ducks in Manitoba have tested positive for H5N1 avian flu viruses, but not the dangerous form of the virus circulating in Southeast Asia, federal officials announced Saturday.

“Canadians can rest assured that we have not detected the Asian strain of avian influenza of animal or human health concern,” Dr. Brian Evans, Canada’s chief veterinary officer said in announcing the findings.

The H5N1 viruses were isolated from two ducks as part of a cross-country surveillance program to find what avian flu viruses are being carried by wild ducks in this country. These viruses are not considered a health threat.

“It’s not surprising necessarily and it wouldn’t be concerning,” Michael Perdue, an avian influenza expert with the World Health Organization’s global influenza program said Saturday from Geneva.

Perdue suggested further such findings should probably be expected.

“As people get more worried and start looking more, they’re going to find more probably.”

The announcement came a day after federal officials revealed a domestic duck sent to slaughter from a farm in British Columbia’s Fraser Valley had tested positive for an H5 virus. The farm has been quarantined as officials try to determine if additional birds are carrying the virus.

Under international regulations, H5 and H7 viruses found in domestic poultry operations must be reported. Those two subtypes of avian influenza have the capacity to produce highly pathogenic strains, which are lethal to chickens.

High-path avian influenza viruses can trigger widespread outbreaks that can lead to huge economic losses for poultry producers, as happened in B.C.’s Lower Mainland in 2004 with the H7N3 strain.

In terms of the wild bird surveillance program, so far all the viruses that have been found – including the H5N1s – are of low pathogenicity, federal officials said.

Other H5 viruses were found in British Columbia and in Quebec, Evans said. Two birds in British Columbia carried H5N9 viruses and five carried H5N2. Two birds in Quebec carried H5N3 viruses. All were low-path viruses.

The Asian H5N1 viruses are highly pathogenic. Those H5N1 viruses have also infected 130 people in five countries since December of 2003; 67 of those people have died.

Canadian scientists who have studied big chunks of the genetic code of the two proteins on the surface of the Manitoba H5N1 viruses have confirmed these viruses are from the family of North American H5N1 viruses, not the strains circulating in Southeast Asia.

North American H5N1 viruses have so far proven to be much milder viruses than their distant Asian cousins, avian influenza experts say.

“We’ve got 32 years of surveillance work that says these North American strains in wild birds in the past have never been a threat,” Dr. Richard Slemons, an avian influenza expert at Ohio State University, said from Columbus on Saturday.

“Does that mean they won’t be a threat in the future? No it does not. But history says they aren’t a risk.”

“Canadians can rest assured that we have not detected the Asian strain of avian influenza of animal or human health concern.”