Abstract

Using molecular techniques, we have been able to characterize different species of amoeba in reptile feces and tissues to assist in epidemiologic investigations. Fatal amoebiasis was diagnosed post-mortem in five individual reptiles representing four different species of lizards (blue-tailed monitor, Varanus doreanus; caiman lizard, Dracaena guianensis; banded ground skink, Eugongylus albofasciolatus; blue tongue skink, Tiliqua scincoides intermedia). The histologic lesions and morphology of the amoebae in these lizards were consistent with Entamoeba invadens infection. The amoeba from the affected lizards was confirmed by PCR on DNA extracted from either frozen or formalin-fixed tissues to be E. invadens with 100% nucleotide identity. Coincidentally, during routine medical screening, amoebae were identified in feces of clinically normal Fiji Island banded iguanas (Brachylophus fasciatus), thus raising suspicion of them as a source of infection for the fatal amoebiasis cases. PCR for Entamoeba sp. was performed on DNA extracted from feces of five of these iguanas. Molecular characterization of PCR results identified a previously undescribed species of Entamoeba in all five iguanas. The Entamoeba found in the Fiji iguanas was most similar genetically to Entamoeba coli with 74% homology vs. 59% homology to E. invadens. This analysis allowed us to exclude the Fiji iguanas as the source of the fatal Entamoeba invadens infections in the other lizards. Application of molecular techniques can be a vital ancillary tool to traditional morphologic evaluations in disease investigations and management decisions.