Typhus, Scrub (Tsutsugamushi)

Abstract

Tsutsugamushi, like epidemic typhus, has been known in the Orient for centuries. In 1810 the Japanese Hakuju Hashimoto described a tsutsuga (disease) along the tributaries of the Shinano River. A similar disease, thought to be carried by mites, or mushi in Japanese, had also been known at least since the sixteenth century in southern China. Sometimes called Japanese flood fever, tsutsugamushi is more commonly known in the United States as scrub typhus – a name used widely by English-speaking troops during World War II. The disease exhibits characteristic typhuslike symptoms of high fever, headache, duration of 2 weeks, and a widespread rash. Distribution and Incidence The geographic boundaries of this malady are defined by the range of its vectors, primarily the trombiculid mites, Lentotrombidium akamushi and Leototrombidium deliensis , and their vertebrate hosts. They extend from India and Pakistan in the West, to Japan and the northern portions of Australia, including all the countries of Southeast Asia, southern China, Korea, the Philippines, and Indonesia, as well as additional islands in the Pacific Ocean (see Map VIII. 153.1). During World War II, the incidence of scrub typhus rose dramatically among military troops, reaching 900 per 1,000 personnel in some areas. It continues to remain a problem in isolated, rural areas. Etiology and Epidemiology The etiologic agent of scrub typhus, Rickettsia tsutsugamushi , is a natural infection of several trombiculid mites, most commonly L. deliensis. Maintained in nature by generational transmission through the eggs of the female, the disease is communicated to humans only during the larval stage of the mite’s life cycle.