Patent Pulmonary Infection with the Invasive Pentastomid Raillietiella orientalis in a Panther Chameleon (Furcifer pardalis) in Belgium

<i>Raillietiella orientalis</i> is an obligate endoparasitic crustacean that is endemic to Southeast Asia and Africa and mainly inhabits the lungs of snake definitive hosts. This pentastomid has emerged as a neozoan parasite in North America, particularly in Florida, where its spread is likely linked to the introduction of nonindigenous Burmese pythons (<i>Python bivittatus</i>), and Australia. In Europe, <i>R. orientalis</i> has previously only been reported in a wild-caught chameleon in Germany. We report a case of <i>R. orientalis</i> infection in a two-year-old male panther chameleon (<i>Furcifer pardalis</i>) which presented with anorexia and respiratory signs. Radiography revealed a diffuse interstitial-alveolar pulmonary pattern, and pulmonoscopy demonstrated numerous adult pentastomids within the lungs and their saccular extensions. Endoscopy-guided removal attempts were unsuccessful. Coprological examination confirmed patent infection through the presence of pentastomid eggs. Morphological assessment and 18S rRNA PCR followed by sequencing identified the parasites as <i>R. orientalis</i>. As antiparasitic treatment with ivermectin and fenbendazole failed and clinical disease persisted, humane euthanasia was performed. This case provides the second description of <i>R. orientalis</i> in a chameleon definitive host and highlights the parasite's capacity for phenotypic plasticity in host utilization. Our findings underscore the potential role of the international reptile trade in facilitating the introduction and dissemination of this invasive pentastomid in Europe.