Scrub Typhus

*Intan Risna/ Tropmed Group 7/ Case 2

The illness also goes by other names, including mite-borne typhus, Japanese river fever, tropical typhus, and tsutsugamushi disease.

O. tsutsugamushi: Rickettsia that lacks lipopolysaccharide and peptidoglycan).

The name “tsutsugamushi” derives from two Japanese words: “tsutsuga”, meaning something small and dangerous, and “mushi”, meaning creature..

Transmission: transovarian in trombiculid (Leptotrombidium) mites. After hatching, infected larval mites (chiggers, the only stage that feeds on a host) inoculate organisms into the skin.

Infected chiggers are found in areas of heavy scrub vegetation during the wet season, when mites lay eggs.

Scrub typhus is endemic in:

• eastern and southern Asia
• northern Australia
• islands of the western Pacific and Indian Oceans.

Clinical Manifestations

Illness varies from mild and self-limiting to fatal.

a. After an incubation period of 6–21 days: fever, headache, myalgia, cough, and gastrointestinal symptoms

* Some patients recover spontaneously after a few days

b. Classic case description:

After 4-6 days of illness: eschar where the chigger feeds, regional lymphadenopathy, and a maculopapular rash starting on the trunk

Severe cases: encephalitis and interstitial pneumonia due to vascular injury

Diagnosis and Treatment

Dx: Serologic assays (IFA, indirect immunoperoxidase, and enzyme immunoassays)

Tx: doxycycline (100 mg bid orally for 7–15 days) or chloramphenicol (500 mg qid orally for 7–15 days).

Others: Azithromycin and clarithromycin.

Sources:

Harrison Internal Medicine. 17th Ed. Chapter 167

http://chppm-www.apgea.army.mil/documents/scrub_typhus_jtf_aug_2006.pdf

http://emedicine.medscape.com/article/971797-overview