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Canada's Guard Is No Chicken

But U.S. still relies on disease-detecting poultry

FRIDAY, June 1 , 2001 (HealthDayNews) -- Their tour of duty finished, an elite group of Canadian border guards has flown the coop. And, basking in the nation's gratitude, most probably will end up as dinner.

But the days of disease-detecting fowl are not over. Down south in the United States, chickens still are on guard from coast to coast for mosquito-borne illnesses, much like canaries in a coal mine.

The 300 Canadian "sentinel chickens" are being retired because health officials realized they probably weren't the best way to detect an invasion by the West Nile encephalitis virus.

"We know they were a big disappointment last year in the Northeast part of the United States," said Harvey Artsob, chief of the Zoonotic Disease department of Health Canada.

The West Nile virus, which caused a scare in New York City in 1999, usually isn't deadly, but its flu-like symptoms can worsen and lead to tremors, paralysis, coma and death, especially in the elderly.

Mosquitoes spread the virus to animals and humans. Birds are susceptible, and the virus is especially deadly to crows. In the New York area, an estimated 90 percent of crows died in just a few months after the virus appeared.

Hence, the border chickens. The virus doesn't make chickens sick, but it does activate their immune systems. Scientists can test their blood for antibodies that would reveal the infection, Artsob says.

"A lot of wild bird species also develop antibodies, but they're not as easy to catch," he says.

Both U.S. and Canadian health officials monitored flocks of chickens for the virus, but because chickens didn't pick up the virus in the U.S. Northeast, even in areas where wild birds had been infected, the Canadians decided to lay off the 600 guard birds they had deployed along the U.S. border from Saskatchewan to New Brunswick.

And their future is unclear, Artsob says. On the bright side, the sentinal chickens have lived longer than their rotisserie-bound compatriots could ever have dreamed, he says.

Meanwhile, there's no evidence that the West Nile virus has crossed into Canada, Artsob says. Health officials will continue to monitor other bird populations, including crows. "Based on the American experience, dead birds are a very good early warning system," he says.

Other Canadian chicken lookouts will avoid the chopping block by continuing to work at the border. Sentinel chickens still are on duty in Saskatchewan and Manitoba, guarding against a deadly strain of encephalitis known as equine, which affects horses and humans.

That disease hasn't appeared in Canada since 1983, but health officials aren't willing to let down their guard.

Meanwhile, U.S. sentinel chickens will stay in Florida and California to check for mosquito-borne illnesses, including West Nile virus and the much more common St. Louis encephalitis.

In Florida, some 1,100 chickens are on guard at any one time, providing about 20,000 blood tests each year.

"Our state has found sentinel chickens to be very effective," says Lillian Stark, a state biological administrator. "When we see a change in the infection rates in our sentinels, we know what to expect and what to look for."

When unusual numbers of chickens are infected, officials warn residents to avoid mosquito bites by wearing long-sleeve shirts and using insect repellent.

The chickens have been used in parts of Florida since the mid-1970s, says Donald Shroyer, medical entomologist in Indian River County.

In a typical year, about 10 sentinel chickens in that county are infected with St. Louis encephalitis, he says. In 1999, nearly all the chickens were infected, and 200 people in Florida came down with the disease, and one died, he says.

What To Do

If you live in an area prone to mosquito infestations, use common-sense precautions to protect yourself.

Learn more about mosquitoes, including how they got that name, in this American Mosquito Control Association fact sheet.

Learn about the West Nile virus in this Q&A presented by a Los Angeles-based mosquito control agency.

And read previous HealthDay articles on mosquitoes and the West Nile virus.

SOURCES: Interviews with Harvey Artsob, chief, Zoonotic Disease department, Health Canada, Winnipeg; Lillian Stark, Ph.D., M.P.H., biological administrator, Bureau of Laboratories, Florida Department of Health, Tampa; Donald Shroyer, Ph.D., medical entomologist, Indian River Mosquito Control District, Vero Beach, Fla.
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