Chelonid Alphaherpesvirus 5 DNA in Fibropapillomatosis-Affected Chelonia mydas

Fibropapillomatosis is a panzootic and chronic disease among Chelonia mydas—usually associated with anthropogenic impacts. This study contributes towards understanding fibropapillomatosis implications for C. mydas populations as a reflector of environmental quality, via prevalence and histological, molecular and blood analyses at a World Heritage site in southern Brazil. Sixty-three juvenile C. mydas (31.3–54.5 cm curved carapace length–CCL) were sampled during two years. Eighteen specimens (~ 29%) had tumours (which were biopsied), while 45 had none. Degenerative changes in the epidermis and Chelonid alphaherpesvirus 5 DNA detection with three variants support a herpesvirus infection. Phylogenetic analysis indicated that variants A and B were similar to a herpesvirus lineage from the Atlantic group, but variant C was similar to a herpesvirus from the eastern Pacific lineage and represents the first published case for marine turtles off Brazil. Significantly lower levels of seven blood parameters, but greater numbers of eosinophils, were observed in tumour-afflicted animals. These observations were attributed to metabolism efficiencies and/or differences in diet associated with temporal-recruitment bias and disease development, and greater non-specific immune stimulation. While most animals had adequate body condition independent of disease, longer-term studies are required to elucidate any protracted population effects.