It wasn't immediately clear how the discovery would affect the commercial industry, which has been under quarantine measures since December and has faced international trade restrictions that in some cases have covered the entire country.
Association president Ray Nickel said the latest infection was confirmed earlier this week at a backyard coop with about 80 egg-laying chickens in Chilliwack, east of Vancouver.
Nickel said the birds were quickly destroyed and the Canadian Food Inspection Agency imposed a one-kilometre surveillance zone around the farm.
The agency did not respond to a request for comment and did not publicly disclose the latest avian influenza case.
The outbreak began last December, hitting 11 commercial chicken and turkey farms in Abbotsford, Chilliwack and Langley within the span of a few weeks, as well as a backyard coop in Langley.
Before this week, the most recent infection was the first backyard coop in Langley, which was confirmed Dec 19. The last infection at a commercial farm was detected in Langley on Dec. 17.
Federal officials imposed containment measures on a half the province, and 24 jurisdictions — including the United States, Mexico and many Asian countries — subsequently imposed trade restrictions on B.C. or Canadian poultry.
Once each infected site is cleaned and disinfected, the Canadian Food Inspection Agency imposes a 21-day ban before allowing birds onto the farms. That is followed by a three-month surveillance period, after which a farm can be declared free of avian flu.
Trade restrictions that are currently hanging over the industry won't be lifted until that process is finished, though foreign countries don't necessarily have to lift their trade restrictions immediately.
Nickel said it's not clear whether the latest infection at the backyard coop will affect that timeline.
"From what we understand CFIA is saying, backyard non-commercial farms don't have the same impact on border restrictions as commercial farms, but that isn't a guarantee either," he said.
Nickel noted Canada imposed restrictions on poultry from the northwestern United States after avian flu was detected in wild birds and on backyard farms.
The type of avian flu that has been circulating in B.C. and the northwestern United States does not pose a risk to humans, but it is highly contagious and deadly among birds.
The most serious Canadian outbreak of avian flu happened in 2004, when a highly pathogenic strain led to the culling of 17 million birds. It took more than a year for international trading bans to be lifted.