ŠAMNH   The Final Toll The 1999 West Nile virus epidemic in the New York City metropolitan area resulted in 62 cases of encephalitis and 7 deaths. The virus was believed to have infected as many as 1,900 unknowing Queens residents, who did not develop encephalitis. Exotic zoo birds, American crows and at least 20 other North American wild bird species--including cockatiels--and horses were also affected, and quite a few died. The Toll One Year Later In a news release from the US Geological Survey dated September 29, 2000, Dr. Robert McLean, director of the USGS National Wildlife Health Center, said the virus, which has spread from the New York area south into Pennsylvania and Maryland, can now travel much farther because it's infected so many more birds--and bird species--than last year. "We're concerned that the fall migration of millions of birds from and through the 400-mile-wide infected region in the northeastern United States may move West Nile virus southward along the Atlantic and Gulf coast states," Dr. McLean told a press conference. "West Nile virus has been isolated from more than 63 species of birds, including 53 free-ranging species from 8 states. That means it's not a matter of if, but when, the virus will move south." How Far Did It Spread? Though human cases of West Nile were limited to Queens, the Bronx, Manhattan, and Brooklyn in New York City, and to Nassau and Westchester counties, other evidence points to a wider outbreak. Infected mosquitoes, birds, or horses, were found as far north as New York's Saratoga County, as far east as southeastern Connecticut, in several New Jersey counties to the west, and as far south as Baltimore County, Maryland. The seasonal migration of birds to warmer southern climates raises the possibility of the virus spreading to other states. Several agencies and private groups are searching for and testing previously collected animal and human specimens to determine whether the virus was present in the US before the 1999 outbreak. Hopefully this will shed light on how and when the virus was introduced to the United States. As of the end of the year, 392 birds had been tested, and 192--almost half--were positive for West Nile. How Did West Nile Get Here? Federal officials have virtually ruled out the possibility that the virus was deliberately introduced into this country as an act of bioterrorism. A sample had been sent to Iraq a decade ago for diagnostic purposes, but West Nile was never high on a list of possible biological warfare agents. One possibility is that the virus was brought in by an animal, perhaps a bird smuggled into the country. Such smuggling is extremely hard to prevent. Jet planes now speed across the oceans that for millennia acted as natural barriers against the spread of disease. Much of their cargo is humans, and an infected person could easily have carried the virus to North America. Or wild birds may be the culprits. Wild animals have always served as a bridge for a few infectious diseases that can jump to humans. Birds, which can cover thousands of miles in a matter of days or weeks, can spread illness remarkably fast. (This may explain why Lyme disease appeared so quickly in so many parts of the United states.) One thing is known: once a disease escapes into the wild, as West Nile has done, it's almost impossible to get the genie back into the bottle. For the US General Accounting Office's full report to Congress on the 1999 West Nile Outbreak, see www.gao.gov.      4 of 4