Intermediate hosts of Schistosoma mansoni in Brazil

The Brazilian planorbidical chart is slowly but progressively been increased by new data. Distribution of vector species of Schistosoma mansoni, according to Paraense, 1986, may be thus resumed: Biomphalaria glabrata--delimited by parallels 13 and 21 degrees S and meridians 39 and 45 degrees W, area of greater dominance (Southeast Bahia, oriental hal of Minas Gerais and Espírito Santo). It is observed along the coast line of the states of Sergipe, Alagoas, Pernambuco, Paraiba and Rio Grande do Norte. Starting from there, it is found towards the southwest, in the direction to the São Francisco River and South-Center of Minas Gerais. Isolated population may be observed in other states. Its presence is probably, associated to the transmission of schistosomiasis in all areas where it occurs. B. tenagophila--extends it self through a wide strip of coast-line from the South of Bahia (17 degrees 45'S; 39 degrees 15'W), RS (33 degrees 41'S, 53 degrees 27'W). In São Paulo and Rio Grande do Sul states it is found further inland. It is important in schistosomiasis transmission in the Paraiba valley (SP). Isolated populations are observed in the Federal District and Minas Gerais state. B. straminea--better adapter species to climatic variation, having a more dense distribution in the northeast (41 degrees W and 110 degrees S), south of Bahia and northeast of Minas Gerais (150 and 180 degrees S, 400 and 440 degrees W). It is less susceptible than the B. glabrata, being however, the most important responsible for the transmission of S. mansoni in the northeast, chiefly in the northeastern dry area, where it is almost the only transmissive species.