Non-seasonal relapsing fever in Utah

Relapsing fever is characterized by paroxysms of fever and spirochetemia due to infection with Borrelia species. The endemic disease is usually transmitted by soft ticks when they feed on human hosts during summer months. Tick-borne relapsing fever has been described in the western United States since the turn of the century. The soft ticks that transmit the various Borrelia species causing relapsing fever, Ornithodoros hermsi, O. turicatae, and O. parkeri, preferentially inhabit animal burrows, rodent nesting sites, and caves. Most reported infections transmitted by O. hermsi are acquired by persons vacationing in summer cabins that contain rodents nests. The ticks complete feeding in less than 1 h and their bite is seldom painful. Hence, the initial bite often goes unnoticed by the human host. We report a case that is unique due both to the geographic location and the late month of disease occurrence. (DBO).