The parasitism of Schistosoma mansoni (Digenea-Trematoda) in a naturally infected population of water rats, Nectomys squamipes (Rodentia-Sigmodontinae) in Brazil

Schistosomiasis is a health problem in Brazil and the role of rodents in ma intaining the schistosome life-cycle requires further clarification. The in fluence of Schistosoma mansoni on a population of Nectomys squamipes was st udied by capture-recapture (1st phase, from June 1991 to November 1995) and removal (2nd phase, from April 1997 to March 1999) studies at Sumidouro, R io de Janeiro, Brazil. During both phases coproscopic examinations were per formed. At the 2nd phase the rodents were perfused and worms were counted. The population dynamics of parasites was studied. During the Ist phase, fem ale reproductive parameters, longevity, recruitment and survivorship rates and migration patterns were studied in relation to schistosome prevalence. Water contamination (source of miracidia), abundance intermediate host and rodent migration were related to prevalence. The N. squamipes population wa s not obviously influenced by the infection, as shown bit the high number o f reproductive infected females, high longevity of infected individuals and the absence of a relationship between recruitment or survivorship rates an d the intensity of schistosome infection. The data indicate that N. squamip es can increase transmission of S. mansoni in endemic areas and carry it to non-infected areas. Furthermore, this rodent can be used as an indicator o f a transmission focus.