Skin inflammatory (nontumor)
Infectious disorders
Scrub typhus

Author: Mowafak Hamodat, M.D., M.Sc. (see Authors page)

Revised: 19 October 2018, last major update September 2010

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PubMed Search: Scrub typhus [title]

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Cite this page: Hamodat, M. Scrub typhus. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skinnontumorscrubtyphus.html. Accessed December 18th, 2018.
Definition / general
  • Chigger-borne zoonosis of tropical Asia and western Pacific islands, caused by Orientia (formerly Rickettsia) tsutsugamushi
Terminology
  • Formerly called Rickettsia tsutsugamushi but now distinguished from Rickettsiaceae family by differences in cell wall
  • Similar in presentation to other forms of typhus, but caused by agent in a different genus (Wikipedia: Scrub Typhus [Accessed 28 August 2018])
  • "Scrub" refers to the type of vegetation (i.e., terrain between woods and clearings) that harbors the vector but name is not entirely correct because endemic areas can be sandy and semiarid (eMedicine: Scrub Typhus [Accessed 28 August 2018])
Epidemiology
  • Infected large number of soldiers in World War II
  • Today, a frequent cause of febrile illness leading to hospital admissions in indigenous populations in eastern Asia, the southwestern Pacific (Korea to Australia) and from Japan to India and Pakistan
Etiology
Clinical features
  • Travelers with imported disease often become sick before or within a few days of return from an endemic region; unlikely diagnosis if illness begins > 18 days after return (Curr Infect Dis Rep 2009;11:66)
Treatment
Clinical images

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Adult trombiculid mite

Chigger

Eschar

Microscopic (histologic) description
  • Lymphocytic vasculitis of arterioles (not postcapillary venules) causes cutaneous findings
  • Variable thrombosis of vessels
  • Microorganisms are detected in endothelium of skin and other organs using fluorescein-labelled antiserum; also present in macrophages as fine granules on high power
  • Eschar exhibits necrotic ulceration, due to coagulative necrosis of of the epidermis and underlying dermis
  • Often only few neutrophils in the inflammatory infiltrate
Positive stains
Molecular / cytogenetics description
  • PCR is useful for confirmation
Additional references