[Natural infestation of wild rats by Schistosoma mansoni in Guadeloupe: quantitative data on the development and fertility of the parasite].

A study of S. mansoni schistosomiasis in R. rattus and R. norvegicus naturally infected in the Guadeloupean focus confirms the results previously obtained with experimental infections in the Rodents. The number of Schistosomes varies from 1 to 600 (on average: 119 +/- 73) in R. rattus and from 1 to 56 (on average: 21 +/- 14) in R. norvegicus. The sex-ratio for all Schistosomes counted in wild Rats is 1.08 for 51.89 +/- 1.78% males and 48.11 +/- 1.78% females; the difference is not significant. The average size of males is greater in R. rattus (5.48 +/- 0.38 mm) than in R. norvegicus (3.73 +/- 0.28 mm); these values are slightly higher than those obtained with Schistosomes collected eight weeks after experimental exposure of Rats.