Susceptibility and compatibility experiments were carried out with 700 Biomphalaria tenagophila
from the Paraná River basin exposed to infection with Schistosoma mansoni
. Individual infection was performed with 10 miracidia of SJ2
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: Rincón 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 Berón de Astrada (3%) were Class III compatible to the S. mansoni
. None of the 100 snails exposed from Caá-Catí became infected (Class 0 incompatible). Tested samples from Paraguay (Encarnación) were infected (20%) and compatible (Class III).
It was also studied the persistence of the infection in 244 snails of the first generation (F1
) of those that were susceptible from three places. It was demonstrated an increment of the susceptibility in the F1
from Maloyas (χ2
= 27.22; p = 0.0001) and Posadas (χ2
= 4.24; p = 0.04).
The results point out the possibility that schistosomiasis might be able to spread into the Paraná River basin where B. tenagophila