Borrelia burgdorferi (Lyme Disease)

Abstract

After completing this article, readers should be able to:Lyme disease is the most common vector-borne disease in the United States. In the United States, the spirochete Borrelia burgdorferi sensu stricto (hereafter termed B burgdorferi) is the only pathogen that causes Lyme disease. However, in Europe and Asia, Borrelia afzelii, Borrelia garinii, and other related species, in addition to B burgdorferi, cause Lyme disease. In the United States, these bacteria are transmitted by hard-bodied ticks, including Ixodes scapularis (the black-legged tick, commonly called a deer tick) in the East and Midwest and Ixodes pacificus (the western black-legged tick) on the Pacific Coast. Ixodes ricinus (the sheep tick) and Ixodes persulcatus (the taiga tick) are the vectors in Europe and Asia, respectively.Lyme disease occurs only in certain geographic areas in which the ecologic conditions are right to support this zoonotic illness. In Europe, most cases occur in the Scandinavian countries and Central Europe, although cases have been reported throughout Europe. Most cases of Lyme disease in the United States occur in New England, the Mid-Atlantic states, Wisconsin, and Minnesota (Figure 1). It also occurs, although much less frequently, on the Pacific Coast, primarily in Northern California and Oregon. Although the geographic distribution is expanding, more than three-quarters of cases still occur in fewer than 70 counties, an indication of the geographic limitation of the disease. In recen…