Environmental changes from water resource developmental projects affect the epidemiology of water-associated
diseases, as well as malaria and schistosomiasis. Aiming to investigate the occurrence and distribution of
freshwater snails of medical and veterinary importance in the area of inf luence of the Peixe Angical hydroelectric dam, a
survey has been conducted over four years (2004-2008). The study has revealed the occurrence of populations of
Biomphalaria straminea
(Dunker) in all municipalities surrounding the lake. Studies on parasite-mollusc
compatibility were undertaken using 35 populations of
B. straminea, descendants of specimens obtained from that area and
three strains of
Schistosoma mansoni
(Sambon) (BH, CM and CMO). The main results are as follows: (i) among the
1,314 specimens used, eight had been infected (infection index of 0.6%) with only the BH strain, (ii) for
B. straminea
populations, the mortality index was 6.8% and, depending on the strain used, the indexes were 4.6%, 8.49% and
19% with BH, CM and CMO strains, respectively, (iii) the infection indexes varied according to the B. straminea
populations, ranging from 0-12.5% and (iv) the duration of the precercarial period varied from 25-49 days. These
results, in addition to environmental and social changes that took place in the Peixe Angical dam region, indicate
the possibility of
B. straminea emerging as a schistosomiasis vector in this area.
