Typhus, mite-borne scrub is a flu-like illness with eschars & lymphadenopathy. "Punched out" skin lesions (papules then eschars) appear at sites of attachment of infected mites. Workers are infected in scrub-overgrown terrain or other mite-infested areas in Central, eastern, & Southeast Asia.
CASES/YEAR
0 (US); 1,000,000 (Global)
OTHER NAMES
Tsutsugamushi disease; Miteborne typhus fever; Orientia tsutsugumushi infection; Scrub typhus;
INCUBATION
6-21 days, usually 10-12 days; [CCDM]
INITIAL SYMPTOMS
Flu-like illness with fever, headache, myalgia, conjunctivitis, transient rash, eschar or eschars, and lymphadenopathy; [CCDM]
PRECAUTIONS
No direct person-to-person transmission; [CCDM]
COMMENTS
FINDINGS:
"Punched out" skin lesions (papules then eschars) appear at the sites of attachment of the infected mites. A rash appears on the trunk one week after onset of the fever in about 1/2 of patients. Pneumonitis is common and may progress to ARDS. Confusion or hearing loss may occur. In untreated cases, fever lasts for 14 days, and the case-fatality rate varies from 1% to 60%. [CCDM, p. 666] The rash starts on the trunk and spreads to the extremities, sparing palms/soles. Hepatosplenomegaly is common. [ID, p. 1488-9] Regional lymphadenopathy is usually present when the eschar appears. In a typical case, there is fever, rash, eschar, lymphadenopathy, and transient hearing loss in a patient 5-20 days after visiting an endemic area. Hematemesis and melena occur frequently. [Guerrant, p. 336] Some patients have elevated liver enzymes. Draining lymph nodes are tender. Leukopenia occurs. Some patients have relapses. [Cecil, p. 2023]
EPIDEMIOLOGY:
Workers are infected in scrub-overgrown terrain or other mite-infested areas. In military operations in "typhus islands," a large percentage of troops may become infected. [CCDM, p. 667] Infected mites live in rural areas suitable for rodent populations. The chiggers feed on rodents, but do not infect them with O. tsutsugumushi.. [Guerrant, p. 334] Case-fatality rate is about 7%, but would be lower if all mild cases were diagnosed. [Harrison ID, p. 694]
COMPLICATIONS:
Rare complications are meningoencephalitis, convulsions, and coma. Pericarditis may develop. [Guerrant, p. 336] Findings may include delirium and myocarditis. [Merck Manual, p. 1699] The pale and transient, macular rash is easy to miss. In severe cases, the disease causes hemorrhages and multiple organ failure. [PPID, 8th Ed, p. 2225]
DIAGNOSTIC
Serology (IFA, indirect immunoperoxidase, and enzyme immunoassays): PCR analysis of eschars and blood; [Harrisons, p. 528]
SCOPE
Central, eastern, and Southeast Asia; from southeastern Siberia and northern Japan to northern Australia and Vanuatu, as far west as Pakistan, and particularly prevalent in northern Thailand; [CCDM]
SIGNS & SYMPTOMS
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>arthralgia
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>fever
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>myalgia
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>relative bradycardia
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G abdominal pain
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G blood in stool
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G diarrhea
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G hematemesis
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G hepatomegaly
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G jaundice
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G liver function test, abnormal
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G nausea, vomiting
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H leukopenia
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H lymphadenopathy
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H splenomegaly
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H thrombocytopenia
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N confusion, delirium
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N headache
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N lethargy
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N seizure
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N stiff neck
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O conjunctivitis, acute
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R cough
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S entry wound with lymph nodes
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S lymphadenitis, acute
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S papules or plaques
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S rash (exanthem)
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S ulcer of skin
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X lung infiltrates
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X pleural effusions
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*acute renal failure
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*ARDS
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*bleeding tendency
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*encephalitis
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*meningitis
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*myelitis
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*myocarditis
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*pericarditis
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*pneumonia
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*pneumonitis
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*rhabdomyolysis
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*shock
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*stupor, coma
RISK FACTORS
- Travel to endemic area
- Work in a medical or research lab
- Work in mite infested area of Central, Eastern, or Southeast Asia
REFERENCES FOR CASES/YEAR
1.
2. (Global) About 1 billion people in the Far East are potentially exposed. One of the 3 most common causes of prolonged fever in rural Asia; [Cecil, p. 2023] "Scrub typhus is a febrile disease endemic to the Asia–Australia–Pacific region, where ~1 million cases occur annually." [CDC: EID journal article]