Studies on the Life Cycle of Litomosoides carinii, Filariid Parasite of the Cotton Rat, Sigmodon hispidus litoralis

Abstract

Investigators of filariasis have long been handicapped and limited in scope of study for lack of a suitable laboratory animal that could be infected quickly, easily and in large numbers. About 43% of the cotton rats caught wild in Florida were naturally infected with L. carinii. The epidemiology of the disease in these rodents was studied and the following arthropods were investigated as possible vectors of the parasite: Aedes aegypti, A. albopictus, A. taeniorhyncus, A. sollicitans, Culex pipiens, Mansonia perturbans, Tabanus spp., Chrysops sp., Culicoides sp., C. furens, C. melleus, Cimexlectularius, Polyplax spinulosa, Ixodes scapularis, Rhopalopsyllus gwni and Liponyssus bacoti. Upon ingestion, microfilariae appeared to be digested or evacuated in all but the tropical rat mite, L. bacoti, in which infective forms developed in the haemocoele. About 14% of mite colonies became infective containing worms 800 [mu] and 1,000 [mu] in length. An average of 4.94 infective worms were found per mite. All cotton rats and white rats became infected when placed in contact with infected mites. No exptl. animals became infected when fed infected mites. The white rat is not a satisfactory host for the parasite dies within 10 or 12 weeks or less after entering this animal. It is now possible to infect large numbers of cotton rats easily and quickly with a filariid parasite thus opening new fields of filariasis investigation.