First report on a Raillietiella orientalis and Kalicephalus sp. co-infection in a wild-caught red-tailed green rat snake (Gonyosoma oxycephalum)

Parasitic diseases are a major but frequently overlooked health concern in reptiles, with consequences that extend beyond individual health issues to broader ecological and conservation concerns. A male red-tailed green rat snake (Gonyosoma oxycephalum), imported from Indonesia, died in quarantine one month after purchase, lacking any signs of illness except for a brief period of anorexia. Following its death, the owner observed a vermicular parasite emerging from the snake's oral cavity, which prompted submission of the animal to necropsy. A high-grade infection with 40 specimens of the pentastomid Raillietiella orientalis was confirmed by morphological and DNA analyses (18s rRNA). Moreover, histological examinations revealed macroscopic and histological evidence of larval migration. This case represents the first documented infection in red-tailed green rat snakes and signifies one of few reports on R. orientalis for Europe. It illustrates the potential introduction of invasive parasites through the exotic pet trade in the absence of adequate pre-import health screening. While the risk of establishment in European ecosystems remains uncertain, such introductions may pose challenges for captive reptiles, zoological collections and the native fauna. In addition, co-infections may alter disease progression and contribute to the pathogenicity of pentastomid infections.