Lyme on the Loose: The story of the Lyme disease epidemic

Named after Old Lyme, Connecticut, Lyme disease, a bacterial infection is transmitted by the bite of the deer tick--though it took many years to figure that out. In the northeastern U.S., a particular set of biological and environmental circumstances have converged to create the perfect conditions for a Lyme disease epidemic.

Though deforestation is commonly linked to outbreaks of infectious disease, in the case of Lyme disease reforestation is the culprit. Farmland has reverted to small patches of forest, creating ideal habitat for deer. Deer populations have skyrocketed, and so have the ticks'. Which wouldn't be a problem, since wild animal populations are the natural reservoirs for the Lyme disease bacteria, if man weren't encroaching on their habitat-but that's exactly what's happening in many suburban areas.

Combining satellite images of vegetation patterns with detailed ground maps, scientists can now pinpoint high-risk locations in New York's Westchester County with astonishing accuracy. Ironically, what appear to be ideal places to live-free-standing houses, with shady lawns next to wooded land-can place their owners at maximum risk of contracting this rarely fatal but potentially serious illness.