Tick-borne relapsing fever in Colorado. Historical review and report of cases

T. A. Edell, J. K. Emerson, G. O. Maupin, A. M. Barnes and T. M. Vernon

Since 1915 the front range of the Colorado Rocky Mountains has been postulated as a focus of endemic tick-borne relapsing fever. However, the disease has rarely been identified: only two cases have been reported in Colorado since 1944. Three sporadic cases in 1977--tightly grouped geographically and temporally--prompted an epidemiologic review. Tick-borne relapsing fever should be considered in the differential diagnosis of recurrent paroxysmal fever--with or without known presence of ticks--whenever exposure in an endemic area is part of a patient's history.