Tracking the Avian Flu

Where did this flu virus originate?
The virus, known as H5N1, was first detected in the chicken population in Hong Kong in 1997. Eighteen people who had handled chickens contracted the flu directly from the birds, developing high fevers, severe respiratory distress, and terrible muscle aches. Six of them died. Alarmed by the high mortality rate, health authorities ordered all 1.5 million chickens in the city to be slaughtered. That seemed to stop the virus