# Invasive Fascioloides magna and Its Italian “Alcatraz”

## TL;DR

This study examines whether an invasive liver parasite in Italy has spread beyond a natural park and finds it is still contained there.

## Contribution

The study integrates parasitology, molecular diagnostics, and GIS to assess the spread of Fascioloides magna in Italy.

## Key findings

- Fascioloides magna remains confined to La Mandria Natural Park, with no evidence of spread to surrounding areas.
- Molecular screening detected the parasite in 9.2% of snails within the park but not outside.
- Ecological conditions outside the park appear unsuitable for the parasite's life cycle.

## Abstract

The deer fluke (Fascioloides magna) is a liver parasite that came to Europe from Northern America in the last centuries. This study aimed to understand if the parasite has spread outside La Mandria Natural Park (LMNP) and which factors could help it spread. From 2012 to 2023, researchers checked the livers and faeces of wild herbivores in LMNP. They also collected snails, which are important for the parasite’s life cycle, and tested them. Cameras were used to see if animals move in and out of the park. The results showed that the parasite is still present inside LMNP, especially in red deer, and only rarely in roe deer. The parasite was not found outside the park, neither in animals nor in snails. Some snails inside LMNP carried the parasite, but snails outside did not. Even though some animals sometimes leave the park, the environment outside does not seem suitable for the parasite to survive and reproduce. Overall, the risk of the parasite spreading outside the park is currently low. However, regular monitoring and strong control measures are still important. This study shows that using different methods together helps manage and control invasive parasites in wildlife.

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.