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 the feces. The disease is transmitted to an uninfected human who scratches the bite and rubs the feces into the wound. Incubation period is one to two weeks. R. prowazekii can remain viable and virulent in the dried feces for many days. The disease will kill the louse and it 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 are used early.
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.
Before World War II, epidemic typhus was a devastating disease for humans. Epidemics occurred throughout Europe from the 17th to the 19th centuries. It was common in prisons, where it was known as Gaol Fever. Before then there is little historical literature available. Widespread epidemics occurred during the Napoleonic Wars and the Irish potato famine of 1846 to 1849. During World War I the disease caused three million deaths in Russia and more in Poland and Romania. Even larger epidemics in the post-war chaos of Europe were only averted by the widespread use of the newly discovered DDT to kill the lice on millions of refugees and displaced persons. A vaccine was also developed in World War II, and today epidemics only occur in Eastern Europe, the Middle East and parts of Africa where living conditions and hygiene are poor.
According to Waclaw Szybalski , the first description of typhus was given in 1083 in a convent near Salerno, Italy. In 1546, Girolamo Fracastoro, a Florentine physician, gave another description of typhus in his famous treatise on viruses and contagion, "De Contagione et Contagiosis Morbis."