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 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: 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 (F
1) of those that were susceptible from three places. It was demonstrated an increment of the susceptibility in the F
1 from Maloyas (χ
2 = 27.22; p = 0.0001) and Posadas (χ
2= 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 exists.
