Bird Flu Basics: What It Is and How It Could Explode

Stefan Lovgren in Bangkok
for National Geographic News
November 23, 2005

On their return last month to the Indian Ocean island of Réunion after a vacation in Thailand, three French citizens began experiencing flulike symptoms.

The initial tests indicated the travelers had contracted "bird flu." Media reports said the tourists had probably been infected with the deadly H5N1 avian influenza strain during a trip to a bird park in Bangkok.

But those fears proved unfounded as further lab results confirmed that the tourists had contracted a normal human flu. The initial results had not distinguished between bird flu and the common flu that widely afflicts humans.

The mix-up underscores public misconceptions surrounding the disease—the distinction between bird flu and the "human flu" is sometimes blurred.

The threat that bird flu, and specifically the H5N1 virus in its current form, presents to humans is often misunderstood.

"The virus that causes sickness and death in chickens, the avian virus, is only rarely the cause of human infection," William Aldis, the World Health Organization (WHO) representative to Thailand, said in an interview at his Bangkok office.

At least 130 people have been infected with bird flu in the past two years. There have been 67 confirmed deaths. Malaria, by contrast, kills more than a million people every year.

What health officials are worried about is the possibility that the bird-flu virus will acquire the ability to easily spread from human to human.

"Unless the virus makes that conversion, we don't have a major public health problem for people," Aldis said.

Mixing Genes

There are many types of bird flu, most of them harmless to their hosts or other creatures. Waterfowl and shorebirds are often thought of as the "reservoirs" for bird-flu viruses.

There are actually several H5N1 strains. The one that has been wreaking havoc in Asia is HPAI H5N1. It is suspected to have arisen in the geese and poultry industry in China.

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