title: Natural history of Rickettsia rickettsii.
mesh_terms: D000818:Animals; D001096:Arachnid Vectors / Q000382:microbiology*; D006801:Humans; D012284:Rickettsia rickettsii / Q000502:physiology*; D012373:Rocky Mountain Spotted Fever / Q000453:epidemiology / Q000635:transmission*; D013987:Ticks / Q000382:microbiology*; D014481:United States