Typhus is one of several similar diseases that is caused by the Rickettsiae bacteria. Of greek origin, meaning hazy or smokey, it describes the state of mind of those affected by the typhus disease. A fever which can reach up to 39C (102F) and a headache, are symptoms which are common to all types of typhus. In some tropical countries, typhus is most often mistaken for another disease known as "dengue".

There are three different forms of typhus. The Epidemic typhus (also known as "louse-bourne typhus"), can often cause epidemics following wars and natural disasters. The causative organism is transmitted by the human body louse, which will leave you with a fever, headache, exhaustion, chills, and rash. This type of typhus is most commonly known as "ship fever" or as "prison fever", because it makes itself known in crowded conditions, namely aboard ships and in prison.

Scrub typhus, or "chigger-borne typhus", is transmitted and caused by chiggers. Chiggers are found in areas of heavy scrub vegetation. Symptoms of this disease are muscle pain, fever, cough, gastrointestinal symptoms, and headache.

Endemic typhus (also called "murine typhus" and "flea-borne typhus") is transmitted by fleas on rats, and sometimes by fleas carried on cats or possums. This form of typhus will leave you with symptoms of joint pain, headache, chills, nausea, fever, vomiting, and cough.

Typhus is treated with tetracycline or other tetracycline related antibiotics. Rickettsiae causes a number of other diseases, including Rocky Mountain spotted fever, or "Tick typhus", Boutonneuse fever and Rickettsialpox. Typhoid fever is an entirely different disease than typhus and should not be confused with typhus diseases, despite their similar-sounding names.