West Nile Virus--Part 2?

Graphic: Cathleen Heard

When the days grew short enough by last November to finally send mosquitoes away from the backyards and parks of New York City, residents and public health officials alike breathed a collective sigh of relief. Mosquitoes has brought West Nile virus encephalitis, sickening 62 and killing seven. Lingering worst-case scenarios envisioned virus-ridden mosquitoes overwintering in the subways, emerging come springtime to spread disease again. As those outside the Apple joked about the implausibility of the subways sustaining life of any kind, local, state, and federal agencies remained on full alert.

"CDC [Centers for Disease Control and Prevention] is working frantically, as has the public health infrastructure in New York, to prepare for surveillance for the upcoming year," says Dawn Wesson, an associate professor of tropical medicine at Tulane University in New Orleans, where monitoring mosquito-borne illness is a way of life.

All the planning may turn...