It's well-known that biodiversity makes ecosystems healthier. But new research shows that biodiversity may make people healthier too. People are less likely to get Lyme disease if they live in areas with a greater diversity of small mammals, according to the June issue of Conservation Biology.
This is the first study showing that biodiversity may reduce the risk of disease in people.
"Our work addresses underlying ecological interactions that may cause large-scale variation in disease risk," says Richard Ostfeld of the Institute of Ecosystem Studies in Millbrook, New York, who collaborated with Felicia Keesing of Siena College in Loudonville, New York.
Caused by a spirochete bacterium, Lyme disease is transmitted by ixodid ticks. The disease can cause a characteristic skin rash, flu-like symptoms, arthritis and neurological damage. As many as 17,000 cases are reported to the CDC each year, making it the most common vector-borne disease in the U.S. Lyme disease is concentrated in the northeast, mid-Atlantic and upper midwest.
In part because the disease can be difficult to diagnose and a recently-approved vaccine is not completely effective, the best safeguard against Lyme disease is to avoid ticks. The ticks are born without the Lyme disease bacteria and can become infected during any of three stages (larva, nymph and adult), each of which takes a single blood meal from a host. The nymphs are the most dangerous to people both because they are most active during the summer when people are most likely to be outdoors and because they are hard to detect -- nymphs look like small freckles and are almost impossible to feel when they are crawling around on people's skin. Up to 40% of nymphs in a given area are infected with Lyme disease.
Many ticks never become infected because some hosts transmit
the bacteria inefficiently. In North America, the host that
transmits the bacteria most efficiently is the white-footed
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Contact: Richard Ostfeld
rostfeld@ecostudies.org
914-677-7545
Society for Conservation Biology
4-Jun-2000