The number of cases in Washington DC rose from 10 to 116.
The number of cases in Virginia rose from 274 to 959.
The number of cases in Maryland rose from 1235 to 2576.
"The adult ticks prefer to feed on deer, which are immune to the disease," Mead said. "Deer are the adult mating bars for black-legged ticks. That's where they like to meet their mates, and then they drop off to lay their eggs."
The spread of infected ticks in the Washington region has been dramatic as more farmland has been developed and deer have become ever more common roaming through back yards and parks.
Source: Washington Post