By Emma Patten-Hitt, PhD

ATLANTA, Mar 15 (Reuters Health) - You may be more likely to contract Lyme disease now than you were in 1990, but probably only if you go hiking in Connecticut in July wearing a short-sleeved shirt and shorts, study findings suggest.

The number of cases of Lyme disease, a bacterial infection transmitted by a species of tick, has been on the rise since 1990, according to the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia. The US saw an increase from about 8,000 cases in 1990 to over 16,000 in 1999, although the number decreased slightly from 1998 to 1999.

"The increase might be due to more people getting infected," Stacie Marshall, of the CDC, told Reuters Health, "but may also be due to better reporting of the disease in states where there is a lot of Lyme disease."

Lyme disease is preventable most easily through preventing the bite of the tick, according to Marshall. "You should wear insect repellent, appropriate clothing, check for ticks and stay out of tick-infested areas if possible," she advised.

According to the report in the CDC's Morbidity and Mortality Weekly Report for March 16, the states with the highest number of new Lyme disease cases in 1999 were Connecticut, Rhode Island, New York, and Pennsylvania.

Lyme disease will probably not spread all over the United States, Marshall noted. "It takes quite a few things--you have to have the tick in the area, as well as the ecology--these ticks also need a certain species of deer to mate on to complete their life cycle, and the ticks get infected mostly from a species of rodent called white-footed mice," she explained. "There are only certain areas where all that collides," she added.

"We might see a trend in increasing numbers in the future. We don't know if and when it will level off," Marshall said. But she stated that "there's never been a reported case of a person dying from Lyme disease."

Related MEDLINEplus Pages:

• Lyme Disease