Epidemic typhus, also known as louse-borne typhus, is a form of typhus so named because the disease often causes epidemics following wars and natural disasters where civil life is disrupted. Epidemic typhus is spread to people through contact with infected body lice, in contrast to endemic typhus which is usually transmitted by fleas.Though typhus has been responsible for millions of deaths throughout history, it is still considered a rare disease that occurs mainly in populations that suffer unhygienic extreme overcrowding. Typhus is most rare in industrialized countries. It occurs primarily in the colder, mountainous regions of central and east Africa, as well as Central and South America. The causative organism is Rickettsia prowazekii, transmitted by the human body louse (Pediculus humanus corporis). Untreated typhus cases have a fatality rate of approximately 40%.Epidemic typhus should not be confused with Murine typhus, which is more endemic to the United States, particularly Southern California and Texas. This form of typhus has similar symptoms, but is caused by Rickettsia typhi. It is carried primarily in rat feces and fleas, as well as other rodents. It is not as deadly as louse-born typhus. It occurs only during the summer and fall, when rodents are active among humans. Signs and symptoms
Symptoms of this disease typically begin within 2 weeks of contact with the causative organism.
Signs/Symptoms may include:
Fever
Chills
Headache
Confusion
Cough
Rapid Breathing
Body/Muscle Aches
Rash
Nausea
VomitingAfter 5–6 days, a macular skin eruption develops: first on the upper trunk and spreading to the rest of the body (rarely to the face, palms, or soles of the feet, however).Brill–Zinsser disease, first described by Nathan Brill in 1913 at Mount Sinai Hospital in New York City, is a mild form of epidemic typhus that recurs in someone after a long period of latency (similar to the relationship between chickenpox and shingles). This recurrence often arises in times of relative immunosuppression, which is often in the context of a person suffering malnutrition or other illnesses. In combination with poor sanitation and hygiene in times of social chaos and upheaval, which enable a greater density of lice, this reactivation is why typhus generates epidemics in such conditions. Complications
Complications are as follows
Myocarditis
Endocarditis
Mycotic aneurysm
Pneumonia
Pancreatitis
Kidney or bladder infections
Acute renal failure
Meningitis
Encephalitis
Myelitis
Septic shock

Transmission
Feeding on a human who carries the bacterium infects the louse. R. prowazekii grows in the louses gut and is excreted in its feces. The louse transmits the disease by biting 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.Epidemic typhus has historically occurred during times of war and deprivation.