First symptom is usually a red rash at the site of the bite. Bulls-eye appearance as center clears. Fig 23.15 Flulike symptoms follow. Typhus - caused by rickettsiae, spread by arthropod vectors, infect vascular endothelium and causes inflammation and blockage of capillaries. A. Epidemic typhus - Rickettsia prowazekii, carried by human body louse.
Pathogen grows in GI tract of the louse and is excreted.
Very high mortality rates if untreated. Treat with tetracycline and chloramphinicol B. Endemic murine typhus. Rickettsiae typhi . Common hosts are rats and mice. Transmitted by the rat flea.