Exotic continental gastropods and emerging helminth Parasites: Insights from the Iberian Peninsula

The introduction of exotic species has major impacts on biodiversity, ecosystems, the economy, and public health. A less explored issue is the silent co-invasion of parasites associated with introduced species, often overlooked due to their low detectability. Among these, helminths (e.g., platyhelminths and nematodes) introduced with terrestrial and freshwater gastropods are especially important, given the adaptability and ease of transport and their capacity to act as intermediate hosts or vectors of many parasites capable of infecting humans. Using the Iberian Peninsula as an study example, we conducted a comprehensive literature review of all introduced continental gastropods and analysed their potential health risks by identifying helminth parasites for which these species could act as intermediate hosts or vectors. We recorded 47 exotic gastropod species, mostly snails (93.61%). Since the 1980 s, mollusc introduction records have risen sharply. Thirty-eight helminth parasites (capable of causing 19 different diseases) with potential of infecting humans are linked to 22 exotic gastropod species, especially freshwater taxa. Notably, both freshwater and terrestrial gastropods are associated with a similar number of diseases, including angiostrongyliasis and fascioliasis. Despite the current decline in malacological research activity in the region, new non-indigenous species continue to arrive, mainly via trade and human movement. These introductions pose increasing potential health risks, particularly from widespread yet poorly monitored species. Our results highlight the need for more taxonomic expertise, improved monitoring and prevention programs, parasite screening in introduced species populations, and updates to exotic species lists reflecting emerging bio-sanitary threats.