ABSTRACT
Lyme borreliosis is a multisystem disease resulting from infection by the spirochete Borrelia burgdorferi transmitted by the symptomless bite of certain ticks of the Ixodes species. Although several genospecies of B. burgdorferi sensu lato have been characterized, only B. burgdorferi sensu stricto is endemic in North America (Table 1). The differences in the tick vector in Europe, Eastern Europe, Asia, and North America, the proportion of infected ticks in different geographic areas, the virulence differences of the transmitted Borrelia genospecies, and possible concurrent infection with babesiosis or ehrlichiosis all contribute to the different clinical syndromes in different parts of the world.
