Vancouver - Four poultry farms where an outbreak of avian influenza was discovered in British Columbia are now under quarantine and thousands of their turkeys and chickens will be euthanised, officials said on Wednesday.The Canadian Food Inspection Agency said two more farms have been placed under quarantine, a day after announcing that measure for the first two farms.There are no reports of the disease being transmitted to humans.Tests to determine the precise strain of the virus were conducted Sunday after bird deaths were reported at a turkey farm in Abbotsford and a chicken farm in Chilliwack.All four farms are about 8km apart in the Fraser Valley east of Vancouver.Quarantined farmsThe Abbotsford farm housed 11 000 turkeys that were to be slaughtered for Christmas. Half died from the bird flu. The Chilliwack barn housed 7 000 chickens and about 1 000 of those died.Numbers for the two latest quarantined farms were not available."They are [under quarantine] just on the basis of suspicion. The tests will reveal if they have an influenza or not," said Harpreet Kochhar, Canada's chief veterinary officer.Birds had been moved between the various farms, he said.The remaining birds will be euthanised using carbon dioxide and then composted inside their barns, said Jane Pritchard, British Columbia's chief veterinary officer.Other domestic birdsThe results expected Thursday should show whether the virus is the dangerous H5N1 strain or another variation, said Perry Kendall, British Columbia's provincial health officer.Kochhar said the source of the infection is not yet known. He said the focus is on containing the infection's spread.Kochhar said Hong Kong has suspended the importation of poultry from the Fraser Valley. He said Canada has been in communication with the United States, Japan and the European Union about the outbreak.In 2004, health officials ordered 17 million chickens, turkeys and other domestic birds slaughtered to contain an outbreak of avian influenza at 42 poultry farms in the Fraser Valley, costing industry hundreds of millions of dollars.Avian influenza poses little risk to people who are consuming poultry meat if it is handled and cooked properly. In rare cases, the virus can transmit to people who have had close contact with the birds, health officials said.