Rocky Mountain spotted fever

Rocky Mountain spotted fever is an acute febrile illness transmitted to man by ticks infected with Rickettsia rickettsii. Usually sudden in onset, it is characterized by chills, headache, and fever lasting 2 or more weeks. A characteristic rash appears on the extremities on about the 4th febrile day and spreads to the trunk. The exanthem and other anatomical manifestations result from focal areas of vasculitis and perivascular inflammation scattered throughout the body. Central nervous system (CNS) manifestations of delirium and coma as well as shock and renal failure occur in the severely ill. Serum antibodies to specific rickettsial antigens appear during the 2nd and 3rd weeks of illness. The tetracyclines are highly effective therapeutically.