By Linda Weiford, WSU News
PULLMAN, WASH. – The strain of bird flu causing sickness and the culling of millions of birds in the Midwest is the same strain first detected in Washington state in December, according to a Washington State University scientist who helped identify the virus. Until then, the pathogen had never been seen in the United States.
“We knew we had a foreign strain of avian disease in this country. What we didn’t know was if – and how far – it would spread,” said veterinary pathology professor Tim Baszler, who directs WSU’s Washington Animal Disease Diagnostic Laboratory, or WADDL, the first facility in the U.S. to detect the virus.
After the sample tested positive for a novel H5 avian influenza on Dec. 10, the lab sent it to the U.S. Department of Agriculture’s veterinary laboratory in Ames, Iowa for genetic sequencing.
Two days later, “they delivered the news that confirmed our suspicion,” recalled Baszler.
That is, the virus was the same H5N2 strain that had been wiping out poultry flocks in Asia and western Europe for months and, in recent weeks, had decimated several poultry farms in British Columbia, Canada.
Two weeks before Christmas, the virus was in the Pacific Northwest.
Moving quickly, animal health experts from WSU, the USDA and other state and federal agencies were able to contain the virus. Altogether, it hit four backyard flocks in Washington, one in Idaho and two in Oregon. In California, two commercial poultry farms were struck.
By mid-February, all was quiet.
Until a month later, when the virus began to pound the Midwest, killing and forcing the killing of millions of commercial chickens and turkeys.
Migratory waterfowl carrying the disease have gathered in that region in large concentrations, increasing the likelihood of transmitting the virus, said Baszler. Hardest hit is the Mississippi flyway, a major travel corridor for migratory waterfowl, he said.
By way of flyways
Four flyways exist across the United States, and scientists believe H5N2 entered the U.S. through the Pacific flyway, which runs 4,000 miles from Alaska through western Mexico.
“Even though we were able to contain the virus in the Northwest, the flight path of wild birds from the Pacific corridor overlaps with other flyways,” said Baszler.
Migratory ducks and geese – just like the virus they carry – can be controlled to some degree by surveillance and testing but can’t be geographically sequestered.
“All it takes is a few to venture into an adjacent flyway to keep spreading the disease farther east,” said WSU veterinary microbiologist Rocio Crespo, who oversees WADDL’S avian health and food safety branch in Puyallup, Wash.
H5N2 is extremely contagious and is spread through the droppings and oral secretions of certain species of wild ducks and geese, she explained. Because these birds can carry the virus without getting sick, it travels silently until contact is made with domestic chickens and turkeys and with susceptible wild birds including hawks and eagles, she said.
“It has a high mortality rate and the birds typically die within 48 hours,” she said.
H5N2 is not known to make humans sick, and infected birds are safe to eat when properly cooked, said Crespo. Right now, the biggest concern is that the virus is swiftly expanding its range and killing off large numbers of poultry.
In fact, the more the virus spreads across the Midwest, the more destructive it appears. For instance, scientists are scrambling to figure out how it is infecting chickens and turkeys kept in enclosed commercial facilities – despite ramped-up disease prevention efforts, said Washington Fish and Wildlife veterinarian Kristen Mansfield. She is part of the multi-agency effort to contain the virus after it landed in the Northwest in December.
“What’s puzzling is that some of the biosecurity measures thought to be effective aren’t stopping it,” she said. “It’s possible the virus is being carried inside the facilities by blowing dust or other debris. At this point, it’s just not known.”
Meanwhile, as scientists scramble to better understand this novel bird flu strain, one ray of hope is the sun. The virus, which thrives in cool weather, will likely wane as temperatures warm during the next few weeks.