West Nile Virus

For more than half a century, West Nile virus was someone else’s problem.

The mosquito-borne pathogen was first isolated from a feverish human in 1937 in northern Uganda’s West Nile district. It then lay low for a decade before emerging in an actual epidemic in Israel in 1951. With several Egyptian outbreaks in the early ’50s, researchers started to see the disease infect non-humans, particularly crows and horses. Mosquitoes of the Culex genus appeared to be its chief transmitter, or vector.

By the time the virus hit the United States, in 1999, it had taken on a more sinister character. Where before it mostly struck … » More …