Epidemiologists don't yet know what to make of the discovery of Lyme disease spirochetes in ticks found on mice in Druid Hill Park. So far, the likelihood of a mass disease outbreak is small, even though the park borders crowded neighborhoods, according to Brian S. Schwartz, the Johns Hopkins entomologist who found the bacteria.
That's because of the way the disease is spread. Young deer ticks live on white-footed mice, the type in which Dr. Schwartz found the disease, and they live exclusively in wooded areas. Adult ticks feed on the blood of deer, but there are few deer in the park. Thus, unless the disease is more widely spread throughout the park and two other nearby parks, there is little likelihood of a big outbreak.
Still, although Lyme disease has been found all over Maryland, there is the mystery of just how it got into a city park and how long it's been there. It came to light because an elephant keeper at the Baltimore Zoo, located in the park, contracted Lyme disease last year. The man walked frequently through a grassy area outside the elephants' exercise ground, Dr. Schwartz said, and reported getting numerous ticks on him. Disease hunters called to the scene trapped many small animals, finally catching the two infected woodlands mice.