This Publication Is Searchable The Merck Manual of Diagnosis and Therapy Section 13. Infectious Diseases Chapter 159. An acute, severe, febrile, louse-borne disease caused by Rickettsia prowazekii, characterized by prolonged high fever, intractable headache, and a maculopapular rash. Etiology and Epidemiology R. prowazekii is prevalent worldwide and transmitted to humans in feces of the human body louse Pediculus humanus when a puncture wound is contaminated by scratching. Dried louse feces may also transfer the microbe to the mucous membranes of the eyes or mouth.
Humans are the natural reservoir of infection.
After an incubation period of 7 to 14 days, fever, headache, and prostration suddenly occur. Headache is generalized and intense. Splenomegaly occurs in some cases. For diagnosis and treatment, see Differential Diagnosis and Treatment of Rickettsial Diseases, above. Affected patients either had acquired epidemic typhus earlier or lived in an endemic area.