The susceptibility of Biomphalaria glabrata from Ourinhos, São Paulo, to strains of Schistosoma mansoni from Belo Horizonte, Minas Gerais and S. José dos Campos, S. Paulo, was studied. It was conclude that the molluscs has a high susceptibility to both strains of Schistosoma mansoni.

Among laboratory-bred Biomphalaria glabrata, a live snail in an anomalous shell was found. The anomaly consisted in changes of level in the whorls. The specimen was isolated for a study on its biological behaviour. Afterwards, another specimen displaying a similar anomaly was joined to it. The results obtained showed their biological functions to be normal, their anomaly being of genetic character. In F1 embryos, the anomaly observed was 0.01%. In a 25-month period of investigation, 13 anomalous embryos were isolated. […]

The incubation periods of Biomphalaria glabrata and Biomphalaria tenagophila were compared during one year, in the laboratory. The average time for eggs hatching was 7,6 and 8,0 days for Biomphalaria glabrata and Biomphalaria tenagophila, respectively; the difference was not significant at the 5% level. The fastest development of the eggs was verified in the summer when the average water temperature was approximately 28°C. The analysis of the correlation coeficient showed that the influence of temperature on the egg development period […]

The fecundity (ratio egg-masses per snail, eggs per snail and eggs per egg-mass) and the fertility (hatchability and viability of eggs) of Biomphalaria glabrata and Biomphalaria tenagophila were compared during one year, in the laboratory. The average of eggs per egg-mass was significantly higher in B. glabrata (19.9) than in B. tenagophila (16.2) and both species showed highest fecundity during April. The influence of temperature was very small. The fecundity defined as egg-mass per snail per day was greater in […]

Populations of B. tenagophila and B. glabrata highly susceptible to strains S. mansoni from the Valley of the Paraíba do Sul River (State of S. Paulo) and from Belo Horizonte (State of Minas Gerais), were obtained after four generations using a schedule of individual selections in self-fertilized populations. The rapid genetic gains in susceptibility show that molluscan susceptibility to schistosomiasis infection is highly inheritable, and is apparently conditioned by few genes.

The present research confirms the susceptibility, in laboratory conditions, of an albinic variant of Biomphalaria glabrata from Belo Horizonte (MG), to the infection with a sample of Schistosoma mansoni obtained from wild rodents of the Paraíba do Sul River valley, in the State of São Paulo, Brazil. This account seems to be important, since it is generally thought that B. glabrata is not susceptible to samples of S. mansoni from the Paraíba do Sul River valley. In the discussion, some […]

Descendents of Biomphalaria tenagophila from Minas Gerais, Brazil were experimentally infected with the Schistosoma mansoni. B. glabrata from Belo Horizonte was used as control. The “LE” strain of S. mansoni used in both cases was isolated in Belo Horizonte. B. tenagophila from Itajubá was shown, for the first time, to be susceptible to the strain of S. mansoni adapted to B. glabrata from Belo Horizonte. A 3.3% infection rate was observed, i.e., 5 of the 149 specimen which survived until […]

Seven autochthonous cases of schistosomiasis mansoni are described in this paper. All of them refer to children, 3 to 13 years old, living in Planaltina, Federal District, Brazil. Five out of the seven cases belong to the same family living for 14 years in Planaltina. For the last 4 years this family has lived in a wooden hut 40 meters distant from a breeding place of B. glabrata. Of the 229 snails examined, two were naturallv infected with S. mansoni.

Possible competition between Biomphalaria glabrata and Biomphalaria tenagophila were observed at three natural breeding sites in Ourinhos (SP) between November 27, 1973 and February 20, 1979. The snails were collected every three months until 1976; after this period they were every six months. A total of B. tenagophila 5,249 snails and 353 B. glabrata were collected at the first study site (irrigation ditch); at the second environment 1,703 B. tenagophila and 64 B. glabrata were collected, in the third environment […]

The evolution of sporocysts of Sehistosoma mansoni strains from BH and SJ in their respective vector snails was studied, and aspect and the number of the initial sporocysts were verified during the first weeks of infection. Significant differences were noticed in the number of sporocysts in both strains. Aspects of their development were observed, as well as their distribution throughout the organs, until the cercariae were completely formed.