Schistosoma mansoni: early antimonial treatment of infected mice

The main effect of antimonial treatment in the early phases of schistosome infection is due to an interference with the development of the worm. This effect manifests itself in two different forms: one is a temporary (reversible) delay of development and/or growth, the other, an irreversible blocking of development, leading to the reduction of worm recovery. The antimonials, besides their lethal and toxic effects on the adult worm, exert in vivo a “schistosomistatic” action of variable intensity and duration. The earlier the treatment, the more pronounced is this action, reaching its maximum at the time of cercarial exposure. As a consequence of the temporary delay of the development, the number of the worms became higher in the autopsies conducted at longer intervals from the cessation of treatment. The delay in growth in some cases was followed by a lethal action.