Biomphalaria tenagophila potencial vector of Schistosoma mansoni in the Parana River basin (Argentina and Paraguay)

Susceptibility and compatibility experiments were carried out with 700 Biomphalaria tenagophila from the Parana River basin exposed to infection with Schistosoma mansoni. Individual infection was performed with 10 miracidia of SJ(2) strain from the Paraiba valley (Brazil) originally infective to B. tenagophila. These snails were laboratory-breed progeny of B. tenagophila collected from six localities of Argentina and one from Paraguay. From Argentina: Rincon de Vences (7%) and Posadas (11%) became infected with S. mansoni and the calculation of Frandsen's index (TCP/100) shows that they were Class II poorly compatible. Those snails from Goya (22%), Maloyas (5%), and Beron de Astrada (3%) were Class III compatible to the S. mansoni. None of the 100 snails exposed from Caa-Cati became infected (Class 0 incompatible). Tested samples from Paraguay (Encamacion) were infected (20%) and compatible (Class III). It was also studied the persistence of the infection in 244 snails of the first generation (F-1) of those that were susceptible from three places. It was demonstrated an increment of the susceptibility in the F-1 from Maloyas (chi(2) 27.22; p = 0.0001) and Posadas (chi(2) = 4.24;p = 0.04). The results point out the possibility that schistosomiasis might be able to spread into the Parana River basin where B. tenagophila exists.