Infection with a novel derogenid trematode in a Flap-necked chameleon (Chamaeleo dilepis)

A 2-year-old female Flap-necked chameleon (Chamaeleo dilepis) was presented with a history of anorexia. On physical examination, three 11×4×2 mm, light tan-pink, raised, gelatinous, freely movable, poorly demarcated, raised nodules were identified within the oral cavity. An impression smear contained multiple, light blue to green structures exhibiting an 18×35 μm, elliptical-shaped anterior portion and a single 1×150 μm filament with a tapered end. Initial differential etiologies included trematode ova, flagellate protozoa, fungal sporangia, plant material, and sperm. Fungal culture yielded no growth. The structures described above did not stain with Gomori methenamine silver stain. A calcofluor white stain yielded positive fluorescence. The DNA was extracted from the impression smears and pan-trematode PCR was performed; products were directly sequenced and phylogenetic analysis revealed maximum similarity with a digenean trematode in the family Derogenidae that was distinct from other trematodes for which a reference sequence was available. To our knowledge, this is the first description of cytologic features of trematode ova from an oral lesion in a chameleon.