Scrub Typhus: Clinical, Pathologic, and Imaging Findings

Abstract

Scrub typhus is an acute febrile illness caused by Orientia tsutsugamushi. The main pathologic change is focal or disseminated vasculitis caused by the destruction of endothelial cells and the perivascular infiltration of leukocytes. The diagnosis of scrub typhus is based on the patient's history of exposure, clinical features, and results of serologic testing. Regional and generalized lymphadenopathy is common. The pulmonary manifestations of scrub typhus include interstitial pneumonia, interstitial edema, and hemorrhage caused by vasculitis. Abdominal manifestations include splenomegaly, periportal edema, gallbladder wall thickening, and lymphadenopathy. Although the severity of scrub typhus varies considerably, involvement of the central nervous system is seen in almost all patients and can result in meningoencephalitis. A high degree of clinical suspicion and familiarity with the various radiologic manifestations of scrub typhus allow early diagnosis and timely initiation of appropriate therapy, and thereby may help reduce patient morbidity.

Lymphadenopathy by Scrub Typhus Mimicking Metastasis on FDG PET/CT in a Patient with a History of Breast Cancer

“…Multiple lymphadenopathies with increased FDG uptake disappeared, and FDG uptake of the spleen decreased to within the normal range Discussion Scrub typhus is an acute febrile disease caused by Orientia tsutsugamushi and transmitted to humans through the bite of mite. The disease is endemic in eastern Asia including Korea with 1 million new cases annually [2]. Clinical manifestations and laboratory findings of tsutsugamushi disease are nonspecific, such as fever, cough, gastrointestinal symptoms, leukopenia and abnormal liver function tests.…”

“…Scrub typhus occurs over a wide area of eastern Asia and the western Pacific region [2]. Patients with scrub typhus usually have lymphadenopathy with tenderness in the region of the eschar and generalized lymphadenopathy is a common finding [2]. Furthermore, chest radiographic abnormalities [1,3] and inflammatory changes with spleen enlargement [2,4] were also observed in a previous case of scrub typhus.…”

“…The diagnosis of scrub typhus is based on the patient's history of exposure, clinical features, and serologic testing [1]. Scrub typhus occurs over a wide area of eastern Asia and the western Pacific region [2]. Patients with scrub typhus usually have lymphadenopathy with tenderness in the region of the eschar and generalized lymphadenopathy is a common finding [2].…”

The eschar of scrub typhus

“…The infection begins as a red induration, within 48 hrs enlarges to 8-12mm in diameter that eventually vesiculates and ruptures to form an eschar. 1,2 It is seen in up to 95% of cases, is usually painless and single, though occasionally pruritic. 2 Tender lymphadenopathy may be seen in the draining basin.…”

“…The eschar resolves in 3-4 wks with no sequalae, but may occasionally cause scarring or hyperpigmentation. 1,2 As eschar at the bite site is the single most useful diagnostic clue, all febrile patients without localizing signs of infection should be examined thoroughly for the same. …”