Lyme disease.

Although initially considered a localized epidemic form of arthritis. Lyme disease is now known to have protean manifestation (skin, joint, heart, nervous system) and worldwide distribution. It is caused by infection with the spirochaete Borrelia burgdorferi and is transmitted by a variety of hard ticks and, in some localities, fleas. Antigenic variation between isolates may determine the differences in clinical expression observed between cases in North America and Europe. The reservoir in the animal kingdom is primarily in deer and mice but house pets have also been implicated. The disease is easily treated with oral antibiotics (tetracycline or penicillin) at an early stage but requires parenteral penicillin and can become refractory to medication at late stages. Prompt diagnosis assures the best outcome. Whereas the classic rash, erythema chronicum migrans, is pathognomonic, diagnosis in its absence may rest on serological tests. Bacteriological isolation is seldom successful and is lengthy (Shrestha et al, 1985). Since cloning of the DNA for several of B. burgdorferi antigens has been accomplished, utilization of hybridization techniques may allow rapid detection of the presence of the organism and confirm difficult cases in the future.