(Tsutsugamushi Disease; Mite-Borne Typhus; Tropical Typhus)
Scrub typhus is related to rickettsial diseases and is caused by Orientia tsutsugamushi.
Rickettsiae are a type of bacteria that can live only inside the cells of other organisms (see also Overview of Rickettsial Infections), as do the bacteria that cause scrub typhus. They live in mites (the host).
Scrub typhus occurs in an area of Asia that includes Japan, Korea, China, and India and in northern Australia. The disease is transmitted to people when they are bitten by a chigger (mite larva).
Symptoms of scrub typhus begin suddenly, about 6 to 21 days after the bacteria enter the body. They include fever, chills, a headache, and swollen lymph nodes. A black scab may develop at the site of the chigger bite. People may have a cough during the first week of fever. A rash appears about 5 to 8 days after the fever starts.
The diagnosis of scrub typhus is suggested by symptoms. Doctors may do blood tests that detect antibodies to the bacteria. However, these test cannot detect the antibodies until at least several days after the illness begins. Thus, these tests do not help doctors diagnose the infection immediately after someone becomes ill but can help confirm the diagnosis. To confirm the diagnosis, doctors may do an immunofluorescence assay or use the polymerase chain reaction (PCR) technique.
Treatment of scrub typhus usually consists of the antibiotic doxycycline, taken by mouth, People take this antibiotic until they improve and have had no fever for 48 hours, but they must take it for at least 7 days. With treatment, people recover quickly. Chloramphenicol is also effective but can have serious side effects and is not available in the United States.
Prevention involves clearing brush and spraying infested areas with insecticides to eliminate or decrease the mite population. If people are likely to come in contact with the chiggers, they should use insect repellents such as DEET (diethyltoluamide).