Ecological niche and distribution patterns of snails that host Fasciola hepatica across South America: Unveiling the hidden landscapes

In South America, Pseudosuccinea columella, Galba cubensis, Galba schirazensis, and Galba truncatula snails serve as vectors of Fasciola hepatica, posing significant challenges to public and animal health. This study identified environmentally suitable areas for these species using ecological niche models, including Maxent, Random Forest, and Support Vector Machine (SVM) models. Occurrence points (n = 797) were compiled from the international literature, following the PRISMA protocol, and the malacological collection of the FIOCRUZ Institute in Rio de Janeiro, Brazil. P. columella (51 %) and G. truncatula (18 %) had the highest records. The distribution of Pseudosuccinea columella and G. cubensis was influenced by precipitation, exhibiting a broad potential across South America. In contrast, the distribution of G. schirazensis and G. truncatula was influenced by temperature and was limited to high-altitude areas. An ecological niche overlap was observed between P. columella and G. cubensis and G. schirazensis and G. truncatula. Moreover, suitable areas for these species were identified in Argentina, Peru, Bolivia, and Brazil. In Brazil, P. columella has demonstrated significant environmental suitability in the Cerrado and Amazon Forest biomes, which have been impacted by land-use changes, including pasture expansion and deforestation resulting from unsupervised cattle production. Therefore, predicting the contamination of new areas is critical to mitigate future liver fluke infections in suitable hosts (natives and rural communities, capybaras, etc.) from regions affected by large livestock movements on the continent. As we face climate change threats to vector-borne diseases, these modeling data highlight the need for significant preventive strategies aimed at the welfare and social impact of all South American countries.