Detection of Hexametra angusticaecoides (Nematoda: Ascarididae) in Italian bats: a squamate-associated nematode in mammals

Hexametra angusticaecoides (Nematoda: Ascarididae) is a nematode typically associated with squamate reptiles, particularly lizards (Family Chamaeleonidae, Agamidae, Diplodactylidae). In reptilian hosts, it localizes primarily in the respiratory tract or coelomic cavity and may induce granulomatous lesions, especially under captive conditions. Its life cycle is presumed to be indirect, involving arthropods as paratenic hosts, yet it remains scarcely understood. Despite its broad reptile host range, natural infections in mammals have not been documented to date. Here, we describe the infection by H. angusticaecoides in mammalian hosts. Overall, ten filiform nematodes were recovered from the subcutaneous connective tissue and abdominal cavity of one Kuhl's pipistrelle Pipistrellus kuhlii and one Savi's pipistrelle Hypsugo savii from urban areas in Italy. Molecular analysis of the mitochondrial cox1 gene revealed 100 % identity with H. angusticaecoides sequence from panther chameleons (Furcifer pardalis). This unprecedented finding suggests a potential case of parasite cross-class, dead-end infection event, likely resulting from the ingestion of infected arthropods in ecotones shared by reptiles and bats. It highlights the exposure beyond traditional host boundaries without indicating a breakdown of host specificity in ascaridoid nematodes and emphasizes the need for further investigations into the biology, transmission routes, and ecological interfaces that may facilitate cross-class events.