Comparison of migration and encapsulation of Brugia malayi microfilariae from the midgut to the hemocoel between Anopheles quadrimaculatus and Aedes aegypti.

Comparisons were made of migration and encapsulation of ingested sheathed microfilariae of Brugia malayi from the midgut into the hemocoel between Anopheles quadrimaculatus (refractory and susceptible strains to B. malayi) and Aedes aegypti (Black-eyed, Liverpool strain susceptible to B. malayi). Encapsulation and melanization of microfilarial sheaths and microfilariae occurred in both strains of An. quadrimaculatus and in Ae. aegypti. In both strains of An. quadrimaculatus, by 4 hr and by 24 hr after the ingestion of sheathed microfilariae of B. malayi in the infected bloodmeal, significantly more sheathed microfilariae penetrated the midgut and reached the hemocoel and thoracic muscles compared with those in Ae. aegypti. During the same time periods significantly more encapsulated and melanized microfilarial sheaths and a larger percentage of encapsulated and melanized microfilariae were observed in the hemocoel of both strains of An. quadrimaculatus than in Ae. aegypti. The results suggest that differences observed in the numbers of encapsulated and melanized microfilarial sheaths and percentages of melanized microfilariae between An. quadrimaculatus (both strains) and Ae. aegypti are due to different rates of penetration of the sheathed microfilariae from the midgut to the hemocoel.