There's nothing a germ likes better than a plentiful supply of victims. Infectious diseases are notorious for spreading through daycares, schools, hospitals, and other places where people congregate together.

But humans aren't the only creatures to suffer from infectious diseases. Consider Pasteurella multocida, the germ that produces avian cholera, and its devastating effect on flocks of migrating waterfowl.

Avian cholera is a nasty and highly infectious disease that afflicts some wild birds, causing septicemia, or blood poisoning. It can kill a bird within a few hours. In fact, death can come so quickly that the bird will drop out of the sky or keel over while feeding.

Nasty as it is, avian cholera is not a human health hazard, says Trent Bollinger of the Canadian Cooperative Wildlife Health Centre in Saskatoon.

"The bacterium responsible for avian cholera is not readily transmitted to humans," he says. "As with most infectious agents, cooking will kill the bacterium."

Avian cholera might not be a problem for humans, but it can be a big problem for migrating waterfowl. During migration, waterfowl gather in huge numbers on feeding grounds along the major flyways -- the perfect scenario for an outbreak of infectious disease.

The disease was first reported among migratory birds in the United States in 1944. Since then, it has shown up from time to time throughout the United States, in Canada, and in other countries.

The number of avian cholera outbreaks has increased dramatically in the United States since 1970, and it's now one of the chief causes of death in waterfowl.

In March, a major outbreak of avian cholera was reported in the Rainwater Basin area of Nebraska. Although it's difficult tell how many birds fell victim to the disease, American scientists estimate a death toll in the tens of thousands.

The Rainwater Basin is on a major migration corridor leading, eventually, to western and northern Canada. It's a relatively warm area where ducks, geese, cranes, and other birds pause and feed until the ice is gone from more northerly feeding grounds in northern Nebraska and the Dakotas. That means they are crowded together, in verylarge numbers, for days or weeks at a time.

Avian cholera was first recognized in the Rainwater Basin in 1975 and has reappeared every year since then. Some years the outbreaks are more serious than others, and 1998 seems to have been a particularly bad year.

The symptoms of the disease include convulsions, swimming in circles, throwing the head back between the wings, erratic flight (such as flying upside down or trying to land well above the water), and mucous discharge from the mouth.

Since avian cholera might be carried north into Canada by birds from the Rainwater Basin, the Canadian Cooperative Wildlife Health Centre sent an alert to wildlife officials along the migration routes, asking them to keep a lookout for victims of the disease through April and the early part of May. By late May, the birds have generally reached their breeding grounds and are no longer gathering in the huge flocks that help the disease spread.

Victims of avian cholera were likely to be found only in the southern parts of the migration route. Because the disease acts so quickly, any infected birds would die before reaching the Yukon.

"We can assume that the birds that have reached the Yukon are free of avian cholera, and are as healthy as in previous springs," says Bollinger.

For more information about avian cholera, contact Environment Canada or call the Canadian Cooperative Wildlife Health Centre at (800) 567-2033.