The importance of some wild rodents as possible reservoir hosts of S. mansoni related to the epidemiologic chain of this parasite and some biological aspects of these rodents were studied in semi-natural habitats. The experiment was performed in an enclosed area of about 1,000 m² situated in Taubaté, State of S. Paulo, one of the endemic area of human schistosomiasis, during a period of three years and six months (from August 1973 to December 1976). Wild rodents of the following species were used as definitive hosts: Holochilus brasiliensis leucogaster, Zygodontomys lasiurus, Oryzomys nigripes eliurus and Cavia aperea aperea. Biomphalaria tenagophila and B. glabrata were used as intermediate hosts. From August 1973 to January 1976 it was not possible to find any B. tenagophila eliminating S. mansoni cercariae nor any rodents infected with the same parasite. In August, 1975, egg patches of B. glabrata snails were accidentaly introduced into the area and in 1976 some adult snails were eliminating S. mansoni cercariae. In that same year, two Holochilus that were born in the area were discharging S. mansoni eggs in their feces. Some biological data were collected from 41 H. b. leucogaster of which 28 individuals were introduced into and 14 were born in the area. The majority of body weights of rodents born in the area and captured for the first time was between 20 and 50 grams. In this group of 41 rodents observed, body weight continued to increase throughout the life span of each individual sampled. Z. lasiurus and C. a. aperea did not show any infection with S. mansoni and they did not leave any progeny in the area. O. n. eliurus reproduced in the area and remaining there for about 100 days did not show any infection with the parasite. Thus, H. b. leucogaster and B. tenagophila, in the absence of infected humans, will hardly maintain the life cicle of schistosomiasis but Holochilus together with B. glabrata would probably maintain the life cicle of S. mansoni in nature without the presence of infected man, since in the area there is a suitable strain of S. mansoni, both for definitive and intermediate hosts.
Schistosomiasis; Schistosoma mansoni; Biomphalaria glabrata; Biomphalaria tenagophila; Holochilus brasiliensis leucogaster; Reservoir