Typhus is an umbrella term used to describe a variety of conditions caused by bacteria in the Rickettsiae family. Although there are several forms of typhus, the main types are epidemic typhus, Brill-Zinsser disease, murine or endemic typhus, and scrub typhus. Every form is passed on to humans through infected insects.

Epidemic typhus, also called Rickettisa prowazekii, is caused by contact with body lice. While living on a person’s body, the lice defecate. These feces contain the bacteria that cause typhus. When the person scratches the wounds caused by the lice, the feces are rubbed into the wounds. This form of typhus typically affects large groups of people, as lice spread quickly in areas where people are crowded and unable to bathe regularly.

Symptoms of epidemic typhus include headache, fever, muscle aches, and weakness. A rash consisting of bumps and spots may also develop. This rash begins on the chest, back, and abdomen and spreads to the legs and arms. The brain or heart muscle may also swell in extreme cases, which may be fatal if left untreated.

Brill-Zinsser disease is a form of typhus that is actually a reactivation of a previous typhus infection when a person’s immune system is weakened. This may occur as a complication of illness, surgery, or simply increasing age. Typically, this form of typhus affects individuals years after having overcome epidemic typhus and is quite mild. Symptoms include a week-long fever and a light rash.

Endemic typhus is passed on to humans by fleas. Similar to epidemic typhus, the flea defecates and the person scratches it into the wound. This form of typhus is most common in warm coastal regions, such as California and Texas in the United States. It typically causes a fever that lasts for about twelve days and is accompanied by a headache and chills. In some cases, a light rash may also develop.

Scrub typhus is carried by chiggers or mites. As these insects feed on a human, they deposit the bacteria in the skin. This type of typhus is most prominent in southeast Asia and Japan, particularly during the wet season. Scrub typhus is one of the most common causes of illness for people visiting these regions. The primary symptoms include headache, fever, muscle pains and aches, abdominal pain, cough, diarrhea, nausea, and vomiting. Some sufferers also develop a flat or bumpy rash with spots that develop into crusty scabs.