Another La Nina Winter Means More Lyme Disease Cases
Nov. 28, 1999 (Atlanta) -- Another warm, wet La Niña winter is forecast for a wedge of the northern U.S., and that could mean a big leap in Lyme and other tick-borne diseases, says one public health official.
In the northeastern U.S. and the upper Midwest, tick-borne diseases in general have become an increasing public health threat, Thomas Mather, PhD, director of Rhode Island's Center for Vector-Borne Diseases, tells WebMD. "In a year that's more moist [such as 1998], we see the number of ticks going way up as well as the number of sites in which they're found," says Mather.
"Most Lyme disease cases are contracted between the spring and fall. In fact, ticks are most active during mid to late fall," Kristine A. Smith, a spokesperson for the New York State Department of Health, tells WebMD. "Although cases may be diagnosed during the winter, exposure likely occurred earlier in the year. Early symptoms appear from a week to a few months after exposure."
Lyme disease is a bacterial infection that is especially prevalent in the northeastern and north-central U.S., and is transmitted primarily by infected deer ticks found in moist, shaded environments, especially where there is leaf litter and low-lying vegetation in wooded, brushy, or overgrown grassy areas.
About 70% of those bitten by infected ticks will develop a red, ringlike rash and flu-like symptoms that last between five and seven days -- fatigue, fever, stiff neck, headache, and joint pain. Removing ticks within 24-36 hours may prevent the infection. Adult ticks of fall and winter are easier to see than the tiny baby ticks of spring and summer.
Since 1993, Rhode Island has participated in the CDC's surveillance of ticks and Lyme disease. The patterns he's seen mirror what's happening across the U.S., says Mather. "The large increase in ticks is a significant public health problem."
"For the vast majority of people who contract Lyme disease, it becomes a chronic disease that can be quite debilitating," Sam T. Donta, MD, a Lyme disease expert with the Division of Infectious Diseases at Boston University School of Medicine, tells WebMD