Morphological changes of larval Echinococcus multilocularis in mice treated with albendazole or mebendazole

Using DBA/2J mice, tissue homogenates of larval Echinococcus multilocularis were injected into the mesenteric veins to generate the liver infection. M ice were treated with either albendazole or mebendazole for prolonged perio ds to examine the morphological changes of the metacestode. Albendazole ind uced disorganization of both laminated and germinal layers and suppressed t he maturation of vesicles. Amorphous but loosely laminated PAS-positive mat erial was observed inside the damaged vesicles, although new vesicles sligh tly developed inside or outside of the damaged ones. Active proliferation o f vesicles occurred after treatment with albendazole was terminated. Hydati d cysts were more severely damaged in mice treated with mebendazole and new vesicles did not develop around the damaged ones. Also, hydatid cysts reap peared after treatment with mebendazole was terminated. These results indic ate that these drugs do not eliminate larval E. multilocularis in the long- term, but mebendazole has a higher suppressive effect on multivesiculation than albendazole.