ABSTRACT
This paper introduces the long-term and continuing studies of the authors and their colleagues on several aspects of the host-parasite relations in cotton rat filariasis. Five methods are described for the calculation of the number of infective larvae of Litomosoides carinii transmitted to cotton rats and other laboratory animals by groups of Liponyssus bacoti mites. The relation between the calculated transmission intensities and the number of worms recovered from individual infected animals has been determined by each of the five methods. The accuracy and relevance of each method is discussed and one (method B) has been found to give a better correlation with worm recovery than the others. Some effects of infection with filariasis on the mites are described. The role of heavily infected mites in transmission is questioned and their influence on the calculation of transmission is discussed.
Subject(s)
Disease Models, Animal , Filariasis/transmission , Rats , Animals , Arthropod Vectors , Filariasis/parasitology , Methods , Mites/parasitologyABSTRACT
Delhi and Carworth strains of white rats were exposed quantitatively to infection with Litomosoides carinii and their susceptibility compared. Liponyssus bacoti (= Ornithonyssus bacoti) mites of known (calculated) intensities of infection were used for transmission. The relation between the calculated exposure (= transmission intensity) and the number of adult worms recovered from each rat was established. Adults of both strains of white rat were much "poorer" hosts than cotton rats. All 24 Carworth white rats (100%) and 21/24 of Delhi white rats (87-5%) of differing ages and both sexes became infected. Carworth white rats were generally more susceptible. The susceptibility of newly born Carworth white rats was greatest and was similar to that of cotton rats. Young rats of the Delhi strain were more susceptible than older rats. This strongly suggests "age resistance". The degree of resistance may, however, differ in different species and strains of white rats and in individual rats of the same strain.
