The West Nile virus continues to march across North America at a breathtaking pace. This summer it has been detected in many places in the southern U.S. as well as in southern Canada, and local health authorities everywhere are stepping up surveillance and control efforts. The virus has also claimed its first victim this year, a 71-year-old woman from downtown Atlanta who died on 11 August. Three other elderly people--two in Florida, one in New York City--have fallen ill so far.
West Nile is a mosquito-borne virus that primarily infects birds but can spread to humans and other mammals. Its first outbreak hit New York City in the summer 2 years ago. Last year it spread north to most states in New England and as far south as North Carolina (Science, 24 November 2000, p. 1482). Now, the virus has been found in dead birds in Georgia, Florida, and Louisiana. "It's made a big jump," says virologist Robert Tesh of the University of Texas Medical Branch in Galveston. Meanwhile, researchers at the Canadian Science Centre for Human and Animal Health in Winnipeg have detected the virus in birds from southern Ontario. They are still awaiting confirmation from an independent lab.
Whereas mosquito activity dwindles in the northern United States and Canada by fall, southern states may have to deal with the disease through the winter, Tesh says. And at the rate the virus is advancing, he adds, "I wouldn't be surprised to see it in Houston by the end of the summer."