Neuroangiostrongyliasis Infection Risk Near Preschool Centres in Mallorca, Spain: A Pilot Micro-Epidemiological Study

Neuroangiostrongyliasis, caused by Angiostrongylus cantonensis , is a globally emerging zoonosis, with Spain being the only endemic country in Europe. Human infection occurs through ingestion of gastropods or paratenic hosts carrying third-stage larvae, often leading to eosinophilic meningoencephalitis. Alternative routes such as the ingestion of gastropod mucus or contaminated water have been proposed as potential routes of infection. Young children, particularly those under 5 years old, are at higher risk of neurological complications. This study aimed to assess the risk of neuroangiostrongyliasis transmission in preschool children at an endemic site in Mallorca through a micro-epidemiological approach.

Gastropods from an area where an infected rat was detected were identified and screened for A. cantonensis , with parasitic loads quantified via qPCR. Positive samples were digested to confirm the presence of L3. The distribution of infected gastropods was mapped and analysed for spatial clustering. Teacher surveys were conducted to assess exposure risks within the school.

Overall prevalence in gastropods was 7.38%, with only slugs testing positive, showing a higher prevalence (28.2%). Milax nigricans, Deroceras reticulatum and D. panormitanum were confirmed as intermediate hosts, with D. panormitanum representing a new global host record. L3 larvae were observed in the three slug species. Larval loads ranged from 1 to 20,000 L3s. Infected slugs exhibited a clustered distribution near the positive rat location. Despite the limited epidemiological surveillance, teacher surveys revealed that children place gastropods in their mouths during outdoor activities.

Multiple risk factors for neuroangiostrongyliasis were identified in an endemic area of Mallorca. Enhanced surveillance, improved diagnostics, treatment protocols and public health interventions are needed to prevent paediatric infections in Spain.