4.2 Tsutsugamushi disease and mites

Scrup typus or kedani fever. The pathogen involved is Rickettsia (syn. Orientia) tsutsugamushi, whereas the vector is the larva of the mite Leptotrombidium (syn. Trombicula) akamushi. The disease is a feverish zoonosis distributed at South and East Asia, the Pacific islands and Northern Australia. The natural reservoir is located in small terrestrial mammals and, in Japan, also in quails. - Transmission: Only the larvae (chiggers) of the mite feed on tissue lymph and transfer R. tsutsugamushi transstadially through three entomophagous nymphal stages to the phytophagous imago, in which the next mite generation is reached transovarially. The larvae feed for 1-3 days on warm-blooded animals (fig. 4.7, page 217). After incubation of 1 – 3 weeks, a.primary lesion or "Eschar" appears followed by a swelling of the regional lymph nodes, fever, exanthema (red macular rash on trunk) and heart troubles. Lethality without treatment may rise to 35 %; there is a strain-specific acquired protective immunity. Treatment involves antibiotics, whereas protective measures can be taken by the use of repellents.

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