The disease is caused by a very small parasite of Rickettsia group called Orientiasis tsutsugamushi. It is spread by the bite of a mite (chiggers) technically called trombiculid mite of genus Leptotrombidia. The mite remains in small bushes. A mite can transmit the disease causing organism to its offsprings by transovarian route.
The bite occurs during visit to infected areas (mite islands). In India this may occur during the clearing of fields for agriculture, or during a visit to these areas where toilets are not available. It can also infect soldiers training or staying in bushy jungle areas.
Signs and Symptoms:
The incubation period is usually 7 to 10 days. The illness starts with fever and chills, muscle pains, decreased appetite, vomiting, sometimes diarrhoea, cough and tiredness. Untreated with antibiotics it may last for about 3 weeks before recovery.
On clinical examination, at the site of bite, a small dark (few mms to 1 cm) area may be present. This is difficult to separate from the skin and usually surronded by reddish area. This is known as “ESCHAR”.
If present it helps in diagnosis. Lymphnodes and spleen may enlarge. A rash may be present. Pulse rate is lower than expected for the degree of fever.
Platelets are low. WBC no may be normal usually or sometimes high or low. Liver enzymes and creatinine are raised. Diagnosis is made by antibody levels (IgG and IgM against typhus group).
Chloramphenicol, Doxycycline and Azithromycin have been used. These need to be taken for 5 days or more. Response of fever begins in 2 days and this may aid in diagnosis as well. The disease can be prevented by anti mite measures (personal protection against bites) and DEET etc.