What is causing the bird flu? Could it really kill millions of people?

Dear EarthTalk: What is causing the bird flu? Could it really kill millions of people?

—Dookie Schlemmer, Andover, MA

Bird flu is a viral infection naturally carried by wild birds, notably ducks that can infect other birds but not get sick themselves. Domestic poultry, however, are very susceptible to the disease and usually get sick and die once infected. Humans, in turn, can catch the disease through close contact with infected birds.

When the influenza strain H5N1 appeared in humans in Hong Kong in 1997 and spread quickly to Asia, Africa and Europe, it sent shockwaves throughout the healthcare profession. The spread of the disease was not sufficient to be considered a pandemic (an epidemic worldwide in scope), but it did infect over 200 people and kill about half of them. There have been no documented cases so far of H5N1 moving from human to human, but experts fear that the virus could mutate into a strain that can—and accordingly kill millions of people. It wouldn’t be the first time: Many scientists now believe that the Spanish Flu of 1918, which killed 50 million people (including 675,000 Americans and 43,000 Canadians), started as bird flu.

Some researchers see habitat loss as a key factor in the unusual spread of the disease between wild and domestic birds. A recently released United Nations (U.N.) Environment Programme report found that loss of wetlands around the world has forced migrating wild birds onto stopping points along their way—such as rice paddies and farms—that are ordinarily the domicile of domestic chickens, ducks and geese, with whom they normally don’t mix. “Wetland depletion has direct implications for migrating wild birds,” says David Rapport, a professor at the University of Western Ontario and a lead researcher on the U.N. study. “Wetland habitat worldwide continues to decline, owing to agricultural expansion and urban development, resulting in fewer staging areas for wild migrating birds.”

Rapport warns that “heroic efforts” like mass culling are not likely to appreciably slow the spread of bird flu. The best hope, he says, is to increase habitat for wild birds and avoid siting large-scale poultry operations along migratory bird routes. Minimizing human contact with domestic poultry is also key, but this would be a tall order given the prevalence of poultry in the human diet. Also, in many parts of Asia, separating poultry from people would be at odds with cultural traditions.

Many North Americans may not realize that the bird flu virus has already arrived here. In November 2005 two wild ducks tested positive for H5N1 in Canada, although not the same dangerous strain that affected Southeast Asia. The virus was also found on a domestic duck in British Columbia shortly thereafter. While no infected birds have been documented in the U.S. yet, researchers say it’s only a matter of time.

Just last year U.S. Health and Human Services Secretary Mike Leavitt said that a bird flu pandemic was an “absolute certainty,” echoing repeated warnings from the World Health Organization (WHO). A recently released White House report warns that, if there were to be an outbreak, the nation is unprepared and as many as two million people could die. Meanwhile, Canada has earned kudos from WHO, which is using its billion-dollar preparedness plan as a model for other countries to follow.

CONTACTS: Wildlife Trust, www.wildlifetrust.org/enter.cgi?p=news/2006/0101_1_avian.htm ; Health Canada Avian Flu (Bird Flu) Website, www.hc-sc.gc.ca/dc-ma/avia/index_e.html.