This illness tends to be extremely mild. Endemic typhus is carried by fleas. When a flea lands on a human, it may defecate as it feeds. When the person scratches the itchy spot where the flea was feeding, the bacteria-laden feces are scratched into the skin, thus causing infection. The causative bacteria is called Rickettsia typhi .
Endemic typhus occurs most commonly in warm, coastal regions.
In the United States, southern Texas and southern California have the largest number of cases. Scrub typhus is caused by Rickettsia tsutsugamushi . This bacteria is carried by mites or chiggers. As the mites feed on humans, they deposit the bacteria. Scrub typhus occurs commonly in the southwest Pacific, southeast Asia, and Japan.