Invasive Fascioloides magna and Its Italian "Alcatraz"

Fascioloides magna, an invasive trematode introduced to Europe in the 19th century, persists in two main foci: the Danube basin and La Mandria Natural Park (LMNP) in northern Italy. This study assessed whether the parasite has spread beyond LMNP and evaluated environmental and host-related risk factors. Between 2012 and 2023, 331 wild ruminant livers were examined, and faecal samples were analysed for fluke eggs. Gastropods from the LMNP were sampled using a predictive habitat suitability model and screened for F. magna DNA. Camera traps monitored ungulate movements across LMNP boundaries. Results confirmed the parasite's presence in red and fallow deer within LMNP and sporadic cases in roe deer, but no evidence of infection in wildlife or gastropods outside the park. Molecular screening detected F. magna DNA in 9.2%% of snails inside LMNP only. Despite occasional crossings by potential definitive hosts, ecological conditions outside LMNP appear unsuitable for sustaining the parasite's life cycle. These findings suggest a low current risk of spread but highlight the need for continued surveillance and barrier reinforcement. The integrated approach combining parasitology, molecular diagnostics, and GIS-based risk mapping provides a valuable framework for managing invasive parasitic diseases in wildlife.