Ecological, molecular, histopathological and public health implications of zoonotic metacercariae Clinostomum complanatum (Rudolphi, 1814) in the endemic Anatolian fish, Alburnus escherichii

Aims: Clinostomid metacercariae infect a wide range of freshwater fish species, posing a zoonotic risk to human health when consumed raw or undercooked, potentially leading to Halzoun disease. Although these parasites are generally considered a health threat in Asian countries, they are also present in various regions of Türkiye and have been found in 12 different freshwater fish species commonly consumed in local cultures. However, their presence has not been reported in the endemic Anatolian fish, Alburnus escherichii. This study aims to determine the presence of clinostomid species in A. escherichii from the Sarısu stream in Eskişehir, Türkiye. Methods and Results: In addition to using a combination of ecological, morphological, molecular and histopathological approaches, our findings revealed the presence of Clinostomum complanatum within the branchial and buccal cavities of A. escherichii. Further histopathological examination revealed encysted metacercariae of C. complanatum invading the host tissues encapsulated within a thin fibrotic layer and accompanied by moderate inflammatory cell infiltration and degenerative changes in muscle cells. Conclusions: These results provide new insights into the geographical and host distribution as well as histopathological impacts of C. complanatum metacercariae in teleost species.