Compatibility between Schistosoma mansoni
and Biomphalaria straminea
when exposed to the parasite on the first four months of age was assessed for five parasitological aspects: indices of infection and mortality, duration of precercarial and cercarial periods, and rate of cercarial emission. Infections were made on molluscs from laboratory colonies, at the following ages: 8, 13, 18, 21, 53, 83 and 114 days. Two B. straminea
colonies were used (Camorim, PE and Picos, PI), and one B. glabrata
colony (Ressaca, MG) was used as control. The main results are as follows: (I) infection was significantly associated with mollusc age, being proportionally higher in sexually immature than in mature molluscs for the three colonies; (II) for B. straminea
from Camorim, mortality did not differ significantly between infected and non-infected snails; for B. straminea
from Picos significantly more deaths occurred among infected than among non-infected snails, while the opposite was observed for B. glabrata
from Ressaca; (III) for the three colonies, the precercarial period was significantly shorter for immature molluscs than for mature ones; (IV) the duration of the cercarial period was extremely variable for the three colonies; (V) sexual maturity did not influence cercarial emission for the three colonies.