typhus

Typhus refers to a group of infectious diseases caused by rickettsial bacteria transmitted by arthropod vectors. The illness is characterized by sudden fever, severe headache, myalgia, and often a distinctive rash. Typhus is distinct from typhoid fever, though both can present with fever and malaise.

Epidemic typhus is caused by Rickettsia prowazekii and spread by the human body louse. Murine typhus is caused by Rickettsia typhi and transmitted by rat fleas. Scrub typhus is caused by Orientia tsutsugamushi and spread by larval mites (chiggers) in rural Asia-Pacific regions. A recrudescent form, Brill-Zinsser disease, can occur when latent R. prowazekii reactivates years after the initial infection.

Clinical features include high fever, severe headache, rash, and sometimes confusion or pneumonia. Diagnosis relies on clinical suspicion supported by laboratory tests such as serology (immunofluorescent antibody or ELISA) or PCR; the historical Weil-Felix test is outdated and unreliable. Treatment and prognosis vary by type, but prompt therapy improves outcomes considerably.

Treatment is with doxycycline for most patients; alternatives include chloramphenicol or azithromycin when doxycycline is unsuitable. With appropriate therapy, prognosis improves markedly; untreated infection can be severe and potentially fatal, especially epidemic typhus.

Prevention focuses on vector control and personal protection against lice, fleas, and mites in endemic areas. There is no widely used vaccine for typhus. The diseases remain a public health concern in settings with poor sanitation and crowded conditions.