Clinical and Epidemiological Studies on Rickettsial Infections

Abstract : The observations reported confirm and extend the material previously reported. Thus, in Ethiopia and Burma, as in other areas we are studying, murine typhus is intimately associated with introduced commensal rodents (Rattus, Mus musculus, etc.) and shrews (Suncus) and their ectoparasites, indoors. In Ethiopia, native rodents, like Praomys and Mastomys, that may act like commensals do not seem to play a role in the ecology of this rickettsiosis in the absence of concurrent infestation with Rattus, even though they may be common in domiciles and parasitized by Xenopsylla cheopis, the presumed vector. If Rattus coexist indoors with Praomys, then the latter (and probably other native murines as well) may become secondarily infected on a limited scale. In Rangoon, 5 species of small mammals are peridomestic and all have been frequently found naturally infected with Rickettsia mooseri, the etiological agent. Among the naturally infected fleas found in this study are X. bantorum, Leptopsylla segnis and Ctenocephalides felis. Rat-lice in Ethiopia and Rangoon have also been found to harbor R. mooseri. Rats from shops in Kuching, Sarawak, were demonstrated to have a high rate of natural infection with this rickettsiosis. Infection with the spotted fever-group of rickettsiae was shown to be widespread in Ethiopian rodents, including some 'wild' rodents that entered domiciles.