Transmission

Rocky Mountain spotted fever is a serious tickborne illness which can be deadly if not treated early. It is spread by several species of ticks in the United States, including the American dog tick (Dermacentor variabilis) [PDF – 1 page], Rocky Mountain wood tick (Dermacentor andersoni) [PDF – 1 page], and, in parts of the southwestern United States and Mexico, the brown dog tick (Rhipicephalus sanguineus) [PDF – 1 page]. RMSF cases occur throughout the United States, but are most commonly reported from North Carolina, Tennessee, Missouri, Arkansas, and Oklahoma.