For the effect of epidemic typhus on history, see Typhus in history.
See Typhus for external links and references.

Epidemic typhus

Epidemic typhus, also called Jail Fever, Hospital Fever or Famine fever is a form of typhus caused by the bacillus Rickettsia prowazekii, carried by the human body louse Pediculus humanus humanus. Feeding on a human who carries the bacillus infects the louse. R. prowazekii grows in the louse's gut and is excreted in its feces. The disease is then transmitted to an uninfected human who scratches the louse bite (which itches) and rubs the feces into the wound. The incubation period is one to two weeks. R. prowazekii can remain viable and virulent in the dried louse feces for many days. Typhus will eventually kill the louse, though the disease will remain viable for many weeks in the dead louse.

The symptoms set in quickly, and are among the most severe of the typhus family. They include severe headache, a sustained high fever, cough, rash, severe muscle pain, chills, falling blood pressure, stupor, sensitivity to light, and delirium. A rash begins on the chest about five days after the fever appears, and spreads to the trunk and extremities but does not reach the palms and soles. The infection is treated with antibiotics. Intravenous fluids and oxygen may be needed to stabilize the patient. The mortality rate is 10% to 60%, but is vastly lower if antibiotics such as tetracycline are used early. Infection can also be prevented via vaccination.

Epidemic typhus hits hardest during times of war and privation. For example, typhus killed many thousands of prisoners in Nazi Germany concentration camps during World War II. The abysmally low standards of hygiene enforced in camps such as Theresienstadt and Bergen-Belsen created conditions where diseases such as typhus flourished. A possible modern scenario for typhus epidemics would be in refugee camps during a major famine or natural disaster.

Brill-Zinsser disease

Brill-Zinsser disease is a type of epidemic typhus which recurs in someone after a long period of latency (similar to the relationship between chickenpox and shingles). This type of recurrence can also occur in immunosuppressed patients.