Lyme Disease and the Heart
Lyme disease is caused by bacteria that are transmitted to humans by hard-bodied ticks found in temperate climates throughout the world.1,2 In the United States, the disease is caused by Borrelia burgdorferi sensu stricto and is endemic in areas of the Northeastern and Middle Atlantic regions, as well as the upper Midwest and northern Pacific Coast (Figure 1). Ticks undergo a 3-stage life cycle during which they acquire the Lyme disease bacteria from mice and other rodent hosts and transmit them back to these hosts and to humans. The most common clinical manifestation is an expanding red rash called erythema migrans that occurs in ≈90% of cases (Figure 2). Other disease manifestations can be seen when the bacteria disseminate from the site of initial deposition in the skin to the heart and other organs. Before the discovery of effective antibiotic therapy, more than half of all Lyme disease patients experienced joint manifestations, whereas ≤10% had neurological or cardiac manifestations. The number of people experiencing these complications has decreased markedly since the use of standard antibiotic therapy early in the course of infection.