Molecular detection of Schistosoma species in unusual snail hosts: a note of caution.

The interaction between snails and species of Schistosoma results from an evolutionary process with an intrinsic host-parasite specificity to the snail genus. Faced with this fact, the recent molecular-based report on the potential infection of the thiarid Melanoides tuberculata with human schistosome should be cautiously interpreted. The high sensibility of molecular tools can result in false positives, perhaps by amplifying DNA from an external (contaminant) or invasive stage of schistosome found in this non-permissive snail host. Thus, parasitological data are mandatory to extrapolate the importance of the finding for the epidemiology and control of schistosomiasis.