Lyme disease appears to be on the rise, with the majority of cases occurring in the northeastern and north-central US, according to the Centers for Disease Control and Prevention (CDC), in Atlanta, Georgia. There was a 70% increase in the number of reported cases of the tick-borne illness between 1992 and 1998, from about 10,000 cases per year to almost 17,000. Ninety-two percent of the cases occurred in only ten states - New York, Connecticut, Pennsylvania, New Jersey, Wisconsin, Rhode Island, Maryland, Massachusetts, Minnesota and Delaware.

Most cases occur in June, July and August, when ticks in the immature nymph state tend to feed, and outdoor activities are most common among children and adults. In the nymph stage, the tick is about the size of a poppy seed, and may easily stay attached to the body long enough to transmit the bacteria.

To avoid contracting Lyme disease, CDC officials suggest wearing tick repellents and light colored clothing to make the ticks more visible, or avoiding tick-infested areas altogether. However, because these protective measures "can be inconvenient,'' researchers are currently working to develop new ways to reduce the risk of Lyme disease. Vaccination should be considered for "persons aged 15-70 years who live in areas of moderate to high risk for Lyme disease and have frequent or prolonged contact with tick habitat,'' according to the report.

Morbidity and Mortality Weekly Report April 27, 2000;49:1-9