Epidemic typhus is a serious infectious disease caused by the bacterium Rickettsia prowazekii. It is primarily transmitted to humans through the bites of infected body lice, which thrive in crowded and unsanitary conditions. Symptoms typically include high fever, severe headache, and rash, and if left untreated, the disease can lead to severe complications or death. Historically, epidemic typhus has been associated with wartime and refugee situations, where poor hygiene and overcrowding are common. Vaccines are available, but prevention mainly focuses on improving sanitation and controlling lice populations to reduce the risk of transmission.