Schistosoma mansoni: cercaricidal effects of cedarwood oil and various of its components.

Cercariae of Schistosoma mansoni exposed to cedarwood oil show early phases of the penetration response before they succumb to the toxic effects of the oil. The toxic effect is also seen when cercariae are exposed to certain components of the oil followed by exposure to a known penetration stimulant, linolenic acid, which accelerates the inactivation of the organism. It is postulated that the process of penetration which results in the disruption of the cercarial glycocalyx alters physiological processes related to osmoregulation. This may increase the absorption of the toxic substances in cedarwood oil by the organisms.