Scrub typhus lesion on the leg of a 43 year old man. Scrub, or bush, typhus is caused by infection with the bacterium Orientia tsutsugamushi, which is transmitted to humans by the bite of larval mites known as chiggers. Symptoms include fever, headache, muscle pain and rash. This lesion, known as an eschar, develops a the onset of fever at the site of the chigger bite. Severe cases can cause confusion, internal bleeding and organ failure and can be fatal. Treatment is with antibiotics. The disease is endemic to India, East and Southeast Asia and northern Australia.