Epidemiological Studies on Relapsing Fever in California

Abstract
From 1921 to 1936, 69 cases have been reported. The majority of cases occurred in the summer. The 4 foci responsible for all but 3 cases (one was a laboratory infection) were summer resorts at over 5,000 feet elevation. Chipmunks and tamarack squirrels in 3 foci harbored spirochetes. Ticks (Ornithodorus sp.) were found associated with proved cases.