[Polymorphism of Schistosoma mansoni eggs in the Guadeloupe (French Antilles) focus: presence of S. rodhaini-like parasites?].

A comparative study of egg morphology of Schistosoma mansoni carried out between 9 parasite populations from Guadeloupean foci demonstrates the existence of an intraspecific polymorphism. Three types of lateral spined eggs have been described and their relative proportions observed between populations are related to the participation of a wild host-reservoir (Rattus rattus) in the life cycle of the parasite. Eggs of schistosomes originating from urbanized foci where man plays the main role in the transmission are less polymorphic than those from sylvatic or mangrove foci where rats are involved in the parasite transmission dynamics. In some populations of murine schistosomes, the existence of eggs with an identical shape to those of experimental hybrids between S. mansoni and S. rodhaini suggests the presence of "S. rodhaini-like" parasites in certain foci of schistosomiasis from Guadeloupe.