Epidemiology

Wooded, brushy places are common blacklegged tick habitats.  Campers, hikers, outdoor workers, and others who frequent wooded, brushy, and grassy places are commonly exposed to ticks, and this may be important in the transmission of Lyme disease in some areas.  Because new homes are often built in wooded areas, transmission of Lyme disease near homes has become an important problem in some areas of the United States.  The risk of exposure to ticks is greatest in the woods and garden fringe areas of properties, but ticks may also be carried by animals into lawns and gardens.

Lyme disease has a wide distribution in northern temperate regions of the world.  In the United States, the highest incidence occurs in:

• Northeast, from Massachusetts to Maryland

• North-central states, especially Wisconsin and Minnesota

• West Coast, particularly northern California

In Pennsylvania, the majority of the Lyme disease cases originate in the southeastern counties surrounding Philadelphia,  Additionally, residents in the counties of Butler, Cameron, Clearfield, Elk, McKean, Monroe and Pike are also at higher risk.

Ticks submitted to the Department of Entomology, PSU, since 1988 indicate that the blacklegged tick is increasing in range and abundance within Pennsylvania.  Data obtained from the Pennsylvania Department of Health indicates that the areas of greatest risk of acquiring Lyme disease closely coincide with the PSU tick distribution data.