In October, as senior citizens and others at high risk from flu waited in long lines for shots after half of the United States’ vaccine supply for the season was lost, epidemiologists were already on high alert because of an ominous development halfway around the world. The death in September of a Thai woman who had held her dying daughter in her arms for 10 hours after the girl handled a flu-infected chicken marked the first well-documented human-to-human transmission of a particularly deadly strain of avian flu: a virus that has been simmering in Asia for the past seven years.
Avian flu first made headlines in 1997 when it claimed six lives in Hong Kong. The victims died so quickly that 1.5 million chickens were slaughtered in an attempt to contain it. But the virus has since mutated and spread—most likely by migratory birds—to Vietnam, Thailand, and neighboring areas. So far 31 of the 43 people who became sick by eating or touching infected poultry have died, which amounts to a death rate of more than 70 percent.
Scientists now fear the killer flu may be on the verge of mutating into a form that can easily pass from human to human. A July report by the Animal Influenza Laboratory of China’s Ministry of Agriculture revealed that the virus quickly replicated in mice and grew increasingly virulent in the process. “That opens the possibility that the avian virus could become a real threat to people and spark a new pandemic,” says Richard Webby, a virologist from St. Jude Children’s Research Hospital in Memphis who contributed to the Chinese study. “That’s the big scare.”