Advertisement

B.C. avian flu outbreak came as a surprise and scope is still unknown, officials say

Hens are seen in cages at a state poultry farm on the outskirts of Minsk, November 11, 2013. The biggest farm in Belarus, it produces more than 35 millions eggs every day for the domestic market and for export, mostly for neighboring Russia. REUTERS/Vasily Fedosenko (BELARUS - Tags: AGRICULTURE SOCIETY ANIMALS)

The latest Canadian outbreak of avian flu appears to have caught animal-health authorities by surprise.

Although they seem to have moved quickly to try to contain it, one official admitted they may be dealing with a very virulent strain.

Two more farms in B.C.’s Fraser Valley, just east of Vancouver, were quarantined Wednesday, bringing the number of poultry operations being investigated by the Canadian Food Inspection Agency (CFIA) to four, said chief veterinarian Dr. Harpreet Kochhar.

He also warned that officials aren’t sure the outbreak will be limited to those four, three of which are chicken farms and another that was raising turkeys for the Christmas market.

“As avian influenza is highly contagious and can spread rapidly; it is possible that additional at-risk farms may be identified in the coming days,” Kochhar said.

Chief B.C. Medical Officer Dr. Perry Kendall said there’s no evidence of people being infected by the virus, though health officials are prepared to isolate and treat anyone who might show symptoms.

The two additional chicken farms have not been confirmed as having the virus. They were flagged because both had received shipments of birds from the first and one was experiencing a higher than normal death rate, officials said.

Kochhar said the CFIA expects to get test results in the coming days to pinpoint the exact strain of avian flu and its pathogenicity – how fast it could spread.

"The present mortality does tell us that it is a very virulent virus," he said, but tests will determine how worried they should be about it potentially spreading to other farms.

Dead turkeys showed no obvious signs

Dr. Jane Pritchard, British Columbia’s chief veterinary officer, said they weren’t expecting to find avian influenza when they tested turkeys that were part of a massive die-off last weekend.

Up to 18 birds a day were dying at one farm last week, higher than normal “but not catastrophic,” said Pritchard. But by Sunday, the numbers were getting too high to count.

By Monday they had lost 60 per cent of the flock,” she said.

Necropsies of the dead birds turned up none of the usual signs associated with a bird flu, such as damaged lungs and trachea or bleeding.

“We were actually thinking something must have been in the feed, something must have happened on a management scale,” Pritchard said Wednesday during a conference call with reporters. “But because the losses were catastrophic, part of our normal screening in a catastrophic-loss situation is to screen the birds for avian influenza.

"So immediately all those samples went for avian influenza. We were expecting those to be negative and they came up positive. It was normal protocols because of the high losses that allowed us to catch this in this case.”

It’s at least the sixth time in a decade that Canada is dealing with an outbreak of avian influenza in the economically-important poultry industry.

The CFIA first reported Tuesday that two farms in the Fraser Valley – a turkey operation and a broiler chicken breeder – were found to have an H5 strain of the virus this week. The surviving chickens and turkeys were destroyed.

The toll so far has been around 18,000 birds, not including those likely to be destroyed if the two new suspected farms turn out to be infected.

The outbreak is already having an economic impact. Kochhar confirmed that Hong Kong has suspended importing of poultry and poultry products from the Fraser Valley, even though they’re safe to consume if properly handled and cooked.

“However, there is a reaction in the international community, which continues to actually protect their own industry,” he said.

Poultry production in Canada last year was worth almost $4 billion, with the biggest output coming from Ontario, Quebec and British Columbia. According to Statistics Canada, B.C. produced about 2.7 million turkeys and 101 million chickens in 2013, for a total value of about $230 million.

Kochhar said Canada is working with its close economic partners, including the United States, the European Union and Japan, to limit potential import restrictions through existing “zoning” agreements.

First major outbreak in 2004

Avian flu was largely unknown in Canada until 2004, when a highly contagious strain swept through the Fraser Valley’s poultry operations, forcing the destruction of more than 15 million birds to stamp it out.

The region was hit the following year at two duck farms, and again in 2009 when a low-pathogenic strain was found at a turkey farm. The impact of those outbreaks was limited thanks to quarantine and efforts to prevent contamination through stringent disinfection and restricting access to poultry barns.

Manitoba experienced an outbreak in 2010 of the same strain that hit B.C. the previous year, while a Saskatchewan broiler egg-hatching operation was hit by a highly pathogenic strain in 2007.

Transitory wild birds carrying avian flu have been considered the most likely sources of the infections, but CFIA investigation into the Saskatchewan outbreak did not rule out contaminated drinking water and workers inadvertently spreading the germs through inadequate disinfection procedures.

Kochhar said any one of those things could be responsible for this new outbreak, but it’s not investigators’ prime concern right now.

"Our focus is actually to make sure we are ahead of the game and we are looking at containing the virus spread," he said. "So we are focusing on the epidemiological analysis and looking at establishing those parameters around these impacted premises.”

Kochhar would not say whether the flu is moving steadily eastward but that surveillance programs were in place across Canada to test for the presence of the disease.

The fact that Canada has had a half-dozen reported outbreaks in the last 10 years reflects multiple factors, including bird-migration patterns, shrinking international borders and a globalized economy, he said.

"Right now, it would be hard to actually pinpoint what would be the real factor which would actually result in these coming up as infections," said Kochhar

"But certainly there are eyes on this through the World Organization for Animal Health [and] our surveillance activities in the Canadian Food Inspection Agency … We are actually looking at those indications if there are any.”

Concerns about human vulnerability

Farmers and government animal-health officials learned a lot of lessons from the 2004 outbreak, which also generated fear that the disease might spread to humans after several people died in Asia. Some raised the spectre of SARS (severe acute respiratory syndrome), which had killed more than 40 Canadians the previous year after travelling from Asia.

But it appears most of those infected with avian flu had prolonged close contact with the virus through the handling of diseased poultry.

"Avian influenza rarely affects humans that do not have consistent contact with infected birds," the CFIA stressed in its initial release Tuesday. "Public health authorities stand ready to take precautionary measures as warranted."

Kendall reiterated that Wednesday.

“Transfer of avian influenzas to humans does happen, but it happens very sporadically and is not at all common,” he said. “We’re not currently aware of anybody with an influenza-like illness in the region, though we are in flu season.”

There is no specific vaccine available for avian flu in Canada, though the U.S. Center for Disease Control holds seed quantities of the H5N1 strain, he said.

“Even if you get an animal-to-human transmission, subsequent human-to-human transmission doesn’t happen as far as we can tell, maybe very limited in families,” said Kendall.

[ Related: Avian flu quarantine expands to 4 Fraser Valley farms ]

[ Related: Avian flu in Fraser Valley unlikely to spread: B.C. Poultry Association ]