Tick-borne relapsing fever in the Eastern United States.

Tick-borne relapsing fever is endemic in the western part of the United States, but it has not been reported east of the Mississippi River. Sporadic cases have been reported in the eastern part of the United States, but travel to the West during the incubation period appeared to provide the source of infection. In the fall of 1975, a case of relapsing fever was diagnosed in Cincinnati in a child who had not traveled outside of Ohio, indicating the presence of Borrelia in this area. Serial serological studies indicated that B turicatae was the species involved. The occurrence of this case suggests that relapsing fever may exist in the eastern part of the United States, but its presence may not be appreciated because of the rarity of the disease and the difficulty in confirming the diagnosis.