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Vol.102 Issue 12

CLBC Dec16 1.pdf

Don’t blame the birds  [Peter Mitham]

ABBOTSFORD – Biosecurity trumps birds when it comes to fighting avian influenza, according to several speakers at an industry workshop in Abbotsford on October 20.

“The evidence that migratory waterfowl are the main point of introduction, I don’t agree with it,” declared Armando Mirande, principal of Supervet Inc., a poultry consulting firm just outside Houston, Texas. “The evidence against them is circumstantial at best.”

Mirande capped a day of presentations with a high-powered talk that targeted everything from corruption in his native Mexico, where avian influenza is endemic, to unhelpful practices among producers.

While interactions between waterfowl and domestic flocks are a risk factor, wild birds have become a kind of scapegoose that take the blame for lax biosecurity protocols and other practices that create favourable conditions for the spread of disease.

While it’s become politically and socially acceptable to blame migratory birds, Mirande said this has also diverted attention from the old target: live bird markets where birds are kept in close proximity. Similarly, no one is addressing backyard flocks which can legally number as many as 3,000 birds.

Moreover, the movement of birds within Mexico (to plants that grant sick birds a clean bill of health), not to mention litter – a cheap source of protein for feedlot cattle in northern Mexico – are major risk factors that conceivably contribute to the spread of the disease.

Stronger biosecurity protocols on the ground could do far more to combat the disease than casting eyes to the skies, where Daniel Schwartz, a biosecurity specialist with the Canadian Food Inspection Agency, said the sight of geese above shouldn’t fill farmers with alarm.

In one of the more fascinating facts of the day, Schwartz said Canada geese typically don’t engage in excretion while flying. Rather, they do so prior to take off and once every four to five minutes while foraging.

Schwartz reassured producers that neither they nor their flocks are likely to be pelted with virus-laden poop from airborne fowl.

The greater danger – as in Mexico and elsewhere – lies in the close proximity of wild and domestic birds, and the high concentration of domestic flocks through which avian influenza, once it’s taken hold in a population, can spread.

Victoria Bowes, a diagnostic avian pathologist with the BC Ministry of Agriculture, told producers that wild birds are typically a stable reservoir of low-pathogenic avian influenza. Because the virus has evolved with the population “since forever,” there’s a relatively peaceful coexistence between the two.

The greater danger emerges when bird populations start mingling.

It’s fine and dandy for birds of a feather to flock together, but when viruses jump to a new population, the risks increase.

The virus’ presence in waterfowl doesn’t guarantee its leap to domestic flocks but regular contact between the two groups helps the virus adapt into a risk to domestic birds.

Avian influenza has been found in 20 of 42 migratory species, with strains H3, H4, H6 and H11 being the most common. Yet, not every species will be affected the same way and even if the virus is found, it doesn’t necessarily mean that the species itself is a stable reservoir of the virus.

The variables make it tough to predict the likelihood or the consequences of a jump between populations. A case in point is the 2014 outbreak in BC, when birds from Asia very likely introduced a new strain of the virus. Producers faced a potentially unpredictable element, demanding a prompt response.

“You have to be continually monitoring, because things do change,” Bowes said.

The high concentration of poultry farms in the Fraser Valley makes it a particularly susceptible area for transmission and adaptation of the virus, requiring a better understanding of the exact dynamic at play very important.

“We can be proud of the fact that we’ve had early detection,” Bowes said, noting that lab capacity has typically exceeded the number of incoming samples. “That may not happen next time.”