Cold, Flu, & Cough Health Center

Bird Flu Now Human Killer

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So why worry? Flu viruses do a trick called substitution. If a person gets infected with two flu viruses at the same time, the two viruses can swap genes. When this happens, a bird virus can become a human virus. In a colossal case of bad timing, the bird flu hit the Netherlands at the peak of the human flu season. That's now coming to an end.

Fortunately there's no sign yet that this has happened. It's still not clear why the virus killed the veterinarian, but there's reassuring news. Osterhaus says that the virus he carried was still fully a bird virus. It hadn't picked up genes from any human flu virus.

To be on the safe side, Dutch officials recommend human flu vaccine or Tamiflu for those who come in regular contact with chickens. The idea is to keep them from getting a human flu that might mix with the bird flu.

On the scarier side, it looks as though the bird virus has infected pigs on some farms. Pigs, Pollack notes, are a kind of mixing pot for flu viruses.

The bird flu epidemic in Netherlands and Belgium is not the same virus currently affecting chickens and pet birds in California, Nevada, Arizona, and parts of Texas. The cause of the American epidemic is exotic Newcastle disease. It's deadly to chickens -- and it, too, causes pinkeye in people who handle the animals. While the disease is a terrible blow to the poultry industry in affected areas, it's not considered a threat to humans.