CHARACTERISTICS OF LYME-DISEASE SPIROCHETES IN ARCHIVED EUROPEAN TICKS

To determine whether the characteristics of the Lyme disease spirochet e (Borrelia burgdorferi) in Europe may have changed during the past ce ntury, DNA was amplified from archived Ixodes ricinus ticks. Tick DNA could be amplified, even when ticks had been stored under museum condi tions for nearly a century. Spirochetal DNA was detected by polymerase chain reaction in 6 ticks preserved for as long as a century; the old est was collected in 1884. Borrelia garinii, which predominates in mod ern ticks in the region, infected 3 of these older ticks, and the pres ently infrequent B. burgdorferi sensu stricto infected 2. These data i ndicate that residents of Europe have been exposed to diverse Lyme dis ease spirochetes at least since 1884, concurrent with the oldest recor d of apparent human infection.