VANCOUVER -- The type of avian influenza responsible for an outbreak at poultry farms in southwestern British Columbia is H5N2, a source has confirmed -- the same virus behind at least three other previous outbreaks at Canadian farms.

A turkey farm and a chicken farm located in the Fraser Valley were placed under quarantine earlier this week after H5 avian influenza killed thousands of birds, and two other farms have since been placed under confinement.

A source tells The Canadian Press that tests have determined the virus is a high-pathogenicity, or high-path, strain of H5N2.

Pathogenicity does not indicate the level of danger a virus poses to people. High-path avian flu viruses kill birds, while low-path viruses can reduce egg production.

The Canadian Food Inspection Agency was expected to provide more information Thursday afternoon.

About 18,000 birds are either already dead or set to be euthanized at the original pair of farms. The two other farms that had received chickens from the Chilliwack facility were placed under quarantine on Wednesday, though officials haven't confirmed avian influenza at the new sites.

Officials have cautioned that the virus does not pose a risk to consumers if poultry meat is properly handled and cooked, though in rare cases it can be transmitted to people who work in close contact with the animals.

In 2010, a high-path strain of H5N2 avian flu in Manitoba at a turkey breeder farm led to the destruction of 8,200 birds.

The Fraser Valley has previously seen two outbreaks involving H5N2.

About 74,000 turkeys and chickens were destroyed in 2009 after a low-path strain of H5N2 infected poultry at two Fraser Valley farms, and more than 60,000 ducks and geese were destroyed at two farms in the region in 2005. In both cases, the culprit was a low-path strain of H5N2.

The most serious avian influenza outbreak in Canada was in 2004, when a high-path strain of H7N3 spread to 42 commercial farms and 11 backyard coups in the Fraser Valley. In response, the federal government ordered the slaughter of 17 million chickens, turkeys and other domestic birds.

The current outbreak is already having an economic impact on the Canadian poultry industry.

Since this avian flu was reported, Japan has banned all Canadian poultry products, as well as the import of chicks from B.C.; South Korea has banned chicks from Canada; Taiwan has banned all B.C. poultry and poultry products; and Hong Kong has banned poultry products from the Fraser Valley.

B.C.'s Ministry of Agriculture says the province's poultry industry produced 160 million kilograms of chicken in 2012, and 21 million kilograms of turkey.