Lymes Risk Increases As Forests Shrink

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RISK OF LYME DISEASE INCREASES AS FORESTS SHRINK

Date: 030224
From: http://www.newsday.com/

By Alicia Chang, Associated Press Writer, 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.

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, NJ, 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 environments, we are forcing the animals into smaller and
smaller domains and in so doing, we are increasing the density of
ticks in those residual domains," said Sigal, who was not involved in
the study.

The study focused on 14 maple-dominated forest patches of varying
sizes in Dutchess County, north of New York City. Scientists dragging
out nets to catch ticks found the number of infected ticks increased
as the plots shrank.

In areas of five acres or less, researchers found seven times as many
infected ticks per square meter as compared with the larger fragments.
In one 2-acre plot, they found 80 percent of ticks were infected.

One possible explanation, Keesing said, is that splitting forests
into small parcels alters the population of animals living there.
Predators such as foxes and coyotes usually stray from confined areas
that don't provide enough food, leaving small animals like mice
behind.

* * *

Copyright (c) 2003, The Associated Press
 
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JeffD

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"One possible explanation, Keesing said, is that splitting forests
into small parcels alters the population of animals living there.
Predators such as foxes and coyotes usually stray from confined areas
that don't provide enough food, leaving small animals like mice
behind. "

The main carrier of the ticks that carry lime disease is deer. In fact, they are known as deer ticks. As the biologist points out, splitting forests into smaller units alters the population. Habitats change, and predators move out. That's the case with deer predators, such as the wolf. And creating more shrub, small tree successional forests provides food and shelter for deer. Also, plants that people grow in their yards are food for deer, which will eat just about anything green. This is why land needs to be managed. In some areas fences are put up to keep deer out, in other areas deer are hunted. Hunting replaces the natural preditor, and helps keep an ecological balance by keeping the deer population from exceeding the carrying capacity.

It's important not to slice and dice the woods too much, and leave a good size continual forest between communities. I'm not saying there should be a million acres of pure forest between them, but certainly more than the area of a football field. This is most likely why developments in the Pine Barrens are required to be in clusters.
 
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