DefinitionTyphus is a bacterial disease spread by lice or fleas.Alternative NamesMurine typhus; Epidemic typhus; Endemic typhus; Brill-Zinsser disease; Jail feverCauses, incidence, and risk factorsTyphus is caused by one of two types of bacteria: Rickettsia typhi or Rickettsia prowazekii. The form of typus depends on which type of bacteria causes the infection.Rickettsia typhi causes murine or endemic typhus. Endemic typhus is uncommon in the United States. It is usually seen in areas where hygiene is poor and the temperature is cold. Endemic typhus is sometimes called "jail fever." Lice and fleas of flying squirrels spread the bacteria.Murine typhus occurs in the southeastern and southern United States, often during the summer and fall. It is rarely deadly. Risk factors for murine typhus