Typhus is a disease caused by bacteria (mainly Rickettsia typhi or R. prowazekii). There are two major types of typhus: endemic (or murine typhus) and epidemic typhus. The disease occurs after bacteria (Rickettsia spp.) are transferred to humans usually by vectors such as fleas or lice. Scratching a louse-bite site allows the rickettsia-laden excrement to be inoculated into the bite wound. The rickettsia travel to the bloodstream, and rickettsemia develops. The major pathology is caused by a vasculitis and its complications. Common differentials are: dengue, malaria, typhoid fever, brucellosis, and infectious mononucleosis.