Rickettsia prowazekii is a species of gram-negative bacteria, that is the etiologic agent of epidemic typhus, transmitted in the feces of lice.
Epidemic typhus is a form of typhus so named because the disease often causes epidemics following wars and natural disasters. It primarily shows up in areas of overpopulation and poor economy.
Symptoms include severe headache, a sustained high fever, cough, rash, severe muscle pain, chills, falling blood pressure, stupor, sensitivity to light, delirium and death. A rash begins on the chest about five days after the fever appears, and spreads to the trunk and extremities. A symptom common to all forms of typhus is a fever which may reach 39 °C (102 °F).