Study: Risk of Lyme disease increases as forests shrink

By ALICIA CHANG, of the Associated Press

 

February 23, 2003

 

 

For centuries, gigantic sugar and red maple trees have towered over mice,

squirrels, raccoons and other animals inhabiting dense forests in the

heart of the Hudson Valley (N.Y.).

 

In recent years, urban sprawl has forced the animals to live in carved

patches of forest land. As a result, biologists have found that ticks,

known to be a culprit in the spread of Lyme disease, are on the rise in

smaller forest patches, increasing people's chances of exposure.

 

"This demonstrates that human impact on landscape can influence disease

risk," said Felicia Keesing, a biologist at Bard College, who published

the study in the February issue of the journal Conservation Biology.

 

The study did not address whether smaller forest patch sizes translate to

more confirmed cases of humans contracting Lyme disease.

 

Scientists have long suspected that tampering with nature increases a

person's risk to some diseases due to a shift in animal population, but

few studies have made a direct link. The Bard study found that the density

of infected ticks, a good indicator of Lyme disease cases, were higher in

plots of five acres or less, Keesing said.

 

Federal health officials have said that people who live or work in

residential areas surrounded by tick-infested woods are at a higher risk

of getting Lyme disease.

 

Lyme disease is spread by ticks that live in wooded and grassy areas

nationwide, but especially in the Northeast, from Maine to Maryland, and

in Wisconsin and Minnesota. Ticks become infected by feeding on small

rodents, such as the white-footed mouse, and other mammals infected with

the Lyme disease-causing bacteria.

 

Named for the Connecticut town where it was discovered in 1977, Lyme

disease causes fatigue, fevers and joint pain that can persist for weeks.

Some patients develop severe arthritis. If not treated with antibiotics,

Lyme disease can severely damage the heart and nervous systems.

 

People can avoid contact with infected ticks by wearing long sleeves and

cinching pants cuffs around the ankles when entering tick-infested woods,

quickly removing attached ticks and performing daily tick checks.

 

In 2000, a record 17,300 nationwide cases of Lyme disease were reported to

the Centers for Disease Control and Prevention.

 

Dr. Leonard Sigal, director of the Lyme Disease Center at Robert Wood

Johnson Medical School in New Brunswick, N.J., said the study was further

proof that exposure to Lyme disease is dependent on geographic location.

 

"This is marvelous evidence that as we encroach more and more on these