Studies on Dipetalonema viteae (Filarioidea) I. Microfilaraemia in hamsters in relation to worm burden and humoral immune response.

The course of a primary infection with Dipetalonema viteae was studied in one randomly bred and in one inbred strain of hamster. Worm recovery and the duration and intensity of the microfilaraemia were analyzed and related to the humoral immune response of the host by using the indirect immunofluorescent antibody test on frozen sections of female worms, on eggs and on intact microfilariae. The inbred strain showed a greater susceptibility to the parasite. This was evidenced by high worm recovery and prolonged microfilaraemia. The duration of microfilaraemia did not depend on the number of recovered female worms. Most of the randomly bred hamsters suppressed microfilaraemia by week 30 post infection whereas some hamsters of the inbred strain were still microfilaraemic. Splenectomy prior to infection did not affect the duration of microfilaraemia. Antibodies to the cuticle of microfilariae always appeared in the sera after immunity to circulating microfilariae had been built up.