Brugia malayi: in vitro effects of ivermectin and moxidectin on adults and microfilariae.

The effect of ivermectin and moxidectin on the motility of Brugia malayi adults and microfilariae and on the fertility of B. malayi females was examined. Motility was reduced in adults after exposure to both drugs and worms were non-motile and dead within eight days. The motility of microfilariae was significantly reduced at all drug concentrations and ceased at concentrations of 2500 and 5000mug/mL. The motility of microfilariae released by females was reduced after exposure to both drugs, however ivermectin had a greater effect at concentrations between 170 and 5000mug/mL. Both drugs reduced the number of microfilariae released by females and within four days their release was inhibited. The presence of the bacterial endosymbiont Wolbachia was examined in adults and microfilariae after exposure to increasing concentrations of ivermectin and moxidectin. A decrease in wsp expression was correlated with increasing drug concentration.