Text this: Suscetibilidade de Biomphalaria straminea (Dunker, 1848) de Piripiri (Piauí, Brasil) a duas cepas de Schistosoma mansoni Sambon, 1907 Susceptibility of Biomphalaria straminea (Dunker, 1848) from Piripiri (Piauí, Brazil) to two strains of Schistosoma mansoni Sambon, 1907