Brachiola gambiae sp. n. the microsporidian parasite of Anopheles gambiae and A. melas in Liberia

Brachiola gambiae sp. n., former Nosema cf. stegomyiae, infected natural and insectary colonies of Anopheles gambiae and A. melas in Liberia and reduced susceptivity of the mosquito to development of malaria parasites andtheir transmission to man. It infects most tissues of adult male and female mosquitoes, destroying the midgut, Malpighian tubules, the fat body, muscles, hypoderm and connective tissues. It is usually transmitted with feces released by mosquitoes during feeding on cotton swabs with honey water. In sporogony the oval binucleate spores, 2.5-3 x 1.5-2 μm, have an anisofilar polar filament coiled in 9 coils in one row. Five anterior coils are of larger diameter than the posterior three to four. Macrospores 3-4 x 2 pm form a low percentage of mature spores (1:30). Tubulovesicular secretions are present.