Acid phosphatase activity in the larval stages of Onchocerca volvulus developing in the vector Simulium damnosum.

The staining patterns of acid phosphatase activity of the various larval stages of Onchocerca volvulus from experimentally infected Simulium damnosum s.l. have been described. The enzyme activity was localized in the anal vesicle/pore area of the first-stage larva, in the anal vesicle and intestine of the secong-stage larva and all over the body in the third-stage larva. Early third-stage larvae could be differentiated from late third-stage infective larvae by the presence of pronounced enzyme activity in the rectum area of the former. There were no detectable differences in the staining patterns between the forest and Sudan-savanna strains of O. volvulus developing in S. damnosum.