Longevity of microfilariae following removal of the adult worms
Eberhard, M.L.
Tropical Medicine and Parasitology Official Organ of Deutsche Tropenmedizinische Gesellschaft and of Deutsche Gesellschaft für Technische Zusammenarbeit 37(4): 361-363
1986
ISSN/ISBN: 0177-2392 PMID: 3563316 Document Number: 270021
Four Saimiri sciureus previously infected with Dipetalonema gracile were allowed to develop stable microfilaraemias. All adult worms were then removed surgically from the peritoneal cavity. Weekly microfilaria counts were made on each animal and the decline in microfilariae recorded. At the time of adult worm removal, microfilaraemias ranged from 750 to 12 500 mf/ml. The observed decline in microfilaria densities was gradual, but steady, in all animals. Microfilariae persisted in 1-ml blood samples for 60, 62, 91, and 101 weeks following removal of adult worms. The results indicate clearly that in a naturally produced population, in a natural definitive host, microfilariae survive for 60 to 100 weeks. The gradual decrease in microfilarial densities would appear to be the result of the death of specific batches of broods of microfilariae. The microfilariae which persisted in the blood the longest undoubtedly represent those which were produced just prior to the removal of the adult worms. It is postulated that because of the long life-span of microfilariae, female worms are not called upon to produce a continual supply of microfilariae, nor is the need for mating as frequent as might be expected. Equally important, the number of microfilariae which the host is called upon to phagocytize is considerably smaller than previously suggested.