Studies on Trombiculid Mites (Chiggers) and Other Ectoparasites as Vectors of Rickettsial Infections
Final rept. 1 Sep 1969-30 Jun 1977
MARYLAND UNIV BALTIMORE DEPT OF MICROBIOLOGY
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Research was carried out primarily on the ecology of chigger-borne rickettsiosis scrub typhus and the classification of trombiculid mites chiggers. A total of 27 articles were published with the support of this contract and its predecessors. Included was a critical and extensive review of the ecology of scrub typhus. The demonstration that chiggers belonging to the vector-group of Leptotrombidium occur in the mountains of Ethiopia suggests that scrub typhus may exist there, although it has not yet been conclusively shown to be endemic anywhere in Africa. In the course of the investigations, data were obtained supporting the concept that chiggers are the actual reservoirs as well as the vectors of chigger-borne rickettsiosis. Thus, the infection is maintained in nature by transovarial transmission of rickettsiae from mother to offspring. However, the studies also indicate that under certain conditions e.g., reattachment, or occasional acquisition of true infection, chiggers acquiring Rickettsia tsutsugamushi by feeding on rickettsemic hosts, may actually play a role in perpetuating the cycle or infecting another mammal. As emphasized in some of the articles published under these auspices, topography, geography and ecology are each insufficient to determine the endemicity of scrub typhus in any particular area in the continents where the rickettsiosis is known to occur.
- Medicine and Medical Research