Public parks in the city of Rio de Janeiro, southeast Brazil, and the risk of parasitosis transmission by freshwater gastropods.

Urban parks are not only important for the wellbeing of the human population, but are also widely considered to be potentially important sites for the conservation of biodiversity. However, they may offer risk parasitic infections, such as schistosomiasis and fascioliasis, which are both transmitted by freshwater snails. The present study investigated the occurrence of freshwater gastropods in urban parks of the Brazilian city of Rio de Janeiro, and their possible infection by helminths of medical-veterinary importance. Gastropods were collected from six parks (2021 - 2022) and examined for the presence of larval helminths. In all, 12 gastropod species from different families were collected: Ampullariidae, Assimineidae, Burnupidae, Lymnaeidae, Physidae, Planorbidae, Succineidae, and Thiaridae. The parasitological examination revealed cercaria of three types in five snail species, with the Pleurolophocerca cercariae type in Melanoides tuberculata (the most abundant species), Echinostoma cercariae in Physella acuta and Pomacea maculata, and Virgulate cercariae, in Pomacea sp. and Pomacea maculata. None of the Biomphalaria tenagophila and Pseudosuccinea columella (the most frequent species) specimens were parasitized by Schistosoma mansoni or Fasciola hepatica, respectively. Even so, some parks may represent a considerable potential risk for transmission of both Schistosoma mansoni and Fasciola hepatica, given the presence of these gastropod vectors and the frequent contact of visitors with the waterbodies.