Interaction between Pseudosuccinea columella (Gastropoda: Lymnaeidae) and trematodes in a fasciolosis-endemic region in Espírito Santo, Brazil.

This study aimed to identify larval forms of trematodes in Pseudosuccinea columella from rural properties with a history of bovine fasciolosis in the southern region of Espírito Santo, Brazil. A malacological survey was carried out on waterbodies from ten properties between June 2022 and March 2023. Aquatic snails were collected, identified, and evaluated for infection with trematode larvae by artificial photostimulation. The larvae found were morphologically characterized under a light microscope, and samples of the snails were subjected to histological analysis to observe larval trematodes in development in snails' tissues. A total of 678 specimens of P. columella were collected in nine properties, and larval trematodes were identified in 24 (4.08%) specimens from seven properties. A xiphidiocercaria morphotype, compatible with Haematoloechidae, was found in six properties. A morphotype of echinostome cercaria, compatible with the Echinostoma genus, was found in one property (2.17%). Larval Fasciola hepatica was not observed. Ecological studies are needed to investigate the environmental factors that may be related to the absence of natural infection of snails by F. hepatica, especially considering the presence of positive cattle in the evaluated properties. The data presented here reveal that P. columella a potencial vector role in the studied area.