Canada Bird Flu More Pathogenic Than First Thought

The bird flu strain found last month on a British Columbia farm was more severe than had been thought, but the risk to humans is still low, Canadian health officials said on Tuesday.

The bird flu strain found last month on a British Columbia farm was more severe than had been thought, but the risk to humans is still low, Canadian health officials said on Tuesday.The Canadian Food Inspection Agency also said it has quarantined a second farm in the Fraser Valley of southwestern British Columbia where “a low level of illness appears to exist among some of the birds.”The agency said the strain of virus found in British Columbia is the H7N3 strain, which is more pathogenic, or more virulent, than earlier though. However it is not the same form of the bird flu that has caused several human deaths in Asia and forced farmers to cull millions of birds.Officials had originally identified the flu found Feb. 18, at a farm in Matsqui, British Columbia, as a low pathogenic H7N3 strain of the disease, but testing indicates it was transforming to a high pathogenic strain.”The presence of both forms of the virus on the same premises is not unheard of but is rare,” CFIA said, adding that “Low and high pathogenicity refers to how the virus behaves in birds.”The H7N3 strain is not known to cause illnesses in humans, and initial tests found no indication that the virus had spread to workers at the Matsqui farm.CFIA said that as a safety precaution it had treated the case in Matsqui from the beginning as if it were dealing with a high pathogenic version of the disease. The farm’s 16,000 broiler and breeder chickens were destroyed.Official have said they believe the chickens contracted the flu from ducks or other wild birds in the area.Other poultry farms in the area about 45 miles east of Vancouver were also surveyed.(Source: Reuters HEalth, March 2004)