Rickettsia prowazekii is a type of bacteria that causes typhus, a disease often spread by lice. It is an intracellular parasite, meaning it lives inside the cells of its host. This bacterium can lead to symptoms such as fever, headache, and rash, and can be serious if not treated promptly. The transmission of Rickettsia prowazekii typically occurs when infected lice bite a person or when feces from the lice come into contact with broken skin. Historically, outbreaks have been associated with crowded living conditions, particularly during wars or in refugee camps, highlighting the importance of hygiene and pest control in preventing the disease.