Predictive Approach to Understanding Angiostrongylus cantonensis Distribution in the Canary Islands

Angiostrongylus cantonensis is an invasive parasitic nematode and zoonotic pathogen responsible for eosinophilic meningitis. Originally native to Southeast Asia, it is now globally distributed across tropical and subtropical regions and is approaching Europe, with Tenerife as a key hotspot. This study investigates the distribution and prevalence of A. cantonensis in Tenerife across three host groups (rats, gastropods, lizards). Based on prevalence data, we modelled its potential distribution using species distribution models (SDMs) and compared climatic conditions with Hawaii, a region with frequent human cases. Field surveys confirmed A. cantonensis in endemic and introduced gastropods (25.6%; 179/698), rats (21.5%; 14/79), and lizards (24.0%; 31/129), with local prevalence ranging from 2.4% to 41.6%. MaxEnt and Boosted Regression Tree models identified precipitation seasonality as the main driver of distribution, while prevalence was influenced primarily by tree cover density and climatic variability. Northeastern Tenerife, La Gomera, La Palma, and El Hierro showed the highest habitat suitability. However, overlap with densely populated areas was limited, possibly explaining the absence of reported human cases. The MESS analysis, based on climatic data from Hawaii, indicated moderate to high environmental similarity across most of the Canary Islands, except in northeastern Tenerife, where conditions were outside the range observed in Hawaii. A. cantonensis is firmly established in Tenerife, but human cases remain absent, likely due to limited human exposure, cultural practices, and geographic separation of parasite hotspots from urban zones. Our findings highlight the importance of integrating ecological and epidemiological data in zoonotic risk assessments. Author SummaryThe rat lungworm, Angiostrongylus cantonensis, is a parasitic nematode that can infect the human brain and cause a serious disease known as eosinophilic meningitis. Although it was once limited to Southeast Asia, it has now spread across many tropical regions, and its arrival in the Canary Islands places it close to mainland Europe. In this study, we explored how widespread the parasite is on Tenerife and what environmental conditions allow it to thrive. We examined rats, snails, and lizards from different parts of the island and found that the parasite is well established in all three groups. By combining these field data with environmental information, we built models to predict where the parasite is most likely to occur and compared Tenerifes climate to Hawaii, where human infections are common. Our results show that suitable conditions exist across much of the Canary Islands, but areas where people live densely overlap only slightly with the parasites hotspots. This may explain why no human cases have been recorded so far, even though the parasite is abundant in wildlife.