All the farms are within a 3-mile radius of where the first case was discovered, near Abbotsford, British Columbia, last month. The strain of virus under investigation is not known to affect humans. The two farms were ordered to "depopulate" their flocks, bringing the total number of birds killed since the outbreak began to about 90,000, according to an official at the Canadian Food Inspection Agency.
Tests on the birds at the two new farms are under way. The virus found at the earlier farms was a high-pathogenic version of the H7N3 strain. The pathogenic level reflects the virus's ability to spread between birds.
Officials have said they do not know if the disease was spread between the farms, or if the chickens contracted it from wild fowl in the area along the Fraser River east of Vancouver.