Epidemic Typhus
Epidemic typhus, also called louse-borne typhus, is an uncommon disease caused by a bacteria called Rickettsia prowazekii. Epidemic typhus is spread to people through contact with infected body lice. Though epidemic typhus was responsible for millions of deaths in previous centuries, it is now considered a rare disease. Occasionally, cases continue to occur, in areas where extreme overcrowding is common and body lice can travel from one person to another. In the United States, rare cases of epidemic typhus, called sylvatic typhus, can occur. These cases occur when people are exposed to flying squirrels and their nests.
Source: Centers for Disease Control and Prevention (CDC)