The descriptive epidemiology of Lyme disease in Oklahoma

Lyme disease is a tick-borne illness that primarily occurs in the United States in three endemic areas: the northeast, upper midwest, and pacific coastal regions. Although Oklahoma is considered a non-endemic area of Lyme disease, other tick-borne infections such as Rocky Mountain spotted fever, ehrlichiosis, and tularemia occur at endemic levels. In order to determine the extent of Lyme disease in Oklahoma, the Oklahoma State Department of Health collected information on all possible cases of Lyme disease. The first reported Oklahoma case occurred in 1985. In 1988, and 1989, 8 and 25 cases, respectively, of Lyme disease were reported in Oklahoma residents who acquired their infection indigenously. The mean age of case-patients was 38 years. Twenty-eight of 33 (85%) case-patients were white, and 4 of 33 (12%) were American Indian (race was unknown for 1 case-patient). The female/male ratio was 2.3. Most case-patients had onset of illness between May and September. Twenty-two counties reported cases, with Oklahoma County accounting for 4 of 33 (12%). Only 21 of 33 (64%) recalled a tick bite, and only 19 of 33 (58%) had erythema migrans. Continued active case-finding and passive reporting (as now mandated by state law) will further increase our knowledge of the epidemiology, ecology, and prevention of Lyme disease in Oklahoma.