Synonyms and related keywords: scrub typhus, chigger fever, tsutsugamushi fever, tsutsugamushi disease, akamushi disease, flood fever, inundation fever, island disease, island fever, Japanese river fever, kedani fever, mite typhus, shimamushi disease tropical typhus, Rickettsia tsutsugamushi, R tsutsugamushi, Rickettsia orientalis, R orientalis, Oriental tsutsugamushi, O tsutsugamushi

Background:         
Scrub typhus is an acute, febrile, illness that was first described by the Chinese about 2000 years ago. This illness is caused by Orientia tsutsugamushi, an obligate intracellular gram-negative bacterium, which was first isolated in 1930. Humans are accidental hosts in this zoonotic disease.

The term scrub is used because of the type of vegetation that harbors the vector. The disease is endemic in the "tsutsugamushi triangle," which extends from northern Japan and far-eastern Russia in the north, to northern Australia in the south, and to Pakistan and Afghanistan in the west.

Maldives:
In  2002, an outbreak of febrile illness began in the Maldives. The Ministry of Health, Republic of Maldives, intensified surveillance efforts, and scrub typhus was clinically suspected by the beginning of September.

From May 28, 2002, to April 17, 2003, the Ministry of Health recorded 168 cases with 10 deaths. The disease appears to have a focus (74 cases) in the Gaafu Dhaalu Atoll, including 57 cases and three deaths on Gadhdhoo Island.

Scrub typhus in the Maldives were recorded by British troops during World War II.  Following their arrival in October 1941 on Gan Island, Addu Atoll, the Royal Marines suffered an outbreak of 42 cases. In 1942, 582 cases, 382 in 1943, 92 in 1944, and none in 1945.
Scrub typhus was also documented by an Indian Army survey after the war. According to S.L. Kalra, General Headquarters-India, beech rain forests in the Addu Atoll possessed both the host (rodents), the vector (Chigger mites) of scrub typhus and the rickettsia.

Pathophysiology:
Humans acquire the disease when an infected chigger, the larval stage of trombiculid mites, bites them. The bacteria multiply at the site of bite with the formation of a papule that ulcerates and becomes necrotic, evolving into an eschar, with regional lymphadenopathy that progresses to generalized lymphadenopathy within a few days.

Symptoms
Scrub typhus often appears as a nonspecific fever. Typical symptoms include fever, headache, rash, and lymphadenopathy’ The presence of an eschar is pathognomonic, but it is typically overlooked or misdiagnosed. Pulmonary involvement frequently occurs in mild cases and is the principal cause of death in severe disease.

• Patients experience abrupt onset of high fever (104-105°F), severe headache, myalgia, and eschar (resembling an oval cigarette burn, see picture) with tender regional lymphadenopathy. Less frequently, eye pain, wet cough, malaise, red eye are present.
  
• Toward the end of the first week, approximately 35% of patients develop a centrifugal macular rash on the trunk, which may become raised. By this time, hepatosplenomegaly and generalized lymphadenopathy are present.
  
  A small number of patients have nervous system involvement, with tremors,nervousness, slurred speech, neck rigidity, or deafness during, the second week of the disease.

Medical Care:

• Treatment must be initiated early in the course of the disease, based on presumptive diagnosis, to reduce morbidity and mortality. Doxycycline and chloramphenicol are both effective in the treatment of scrub typhus.
• Seven days of antibiotic treatment is usually effective.
• Meticulous supportive management is necessary to abort progression to disseminated intravascular coagulation (DIC) or circulatory collapse in severe cases.
• Rifampin and azithromycin have been used successfully in areas where scrub typhus is resistant to the conventional therapy.

• In a small Korean trial in children, roxithromycin, a macrolide antibiotic, was as effective as doxycycline and chloramphenicol in the treatment of scrub typhus.

Deterrence/Prevention:

• Preventive measures in endemic areas include protective clothing and insect repellents.

• Short-term vector reduction using environmental insecticides and vegetation control can be instituted.

• Chemoprophylaxis using doxycycline in high-risk groups has been successful. Doses are weekly and must be started before exposure and continued for 6 weeks after exposure.

• No vaccine for scrub typhus is available.

Prognosis:

• Prognosis is variable and depends on the severity of illness, which relates to the different strains of O tsutsugamushi.
  
• Severe disease is uncommon with antimicrobial treatment.