High prevalence of diseases in two invasive populations of red-eared sliders (Trachemys scripta elegans) in southwestern Spain

Non-native turtles are susceptible to pathogenic infections that may be transmitted to native species. We performed hematological, biochemical, histopathological, and microbiological analyses in two invasive populations of red-eared sliders (Trachemys scripta elegans), which were living alongside native turtle species in southwestern Spain. The red-eared sliders that were captured had a healthy external appearance. However, the histopathological analyses revealed that up to 88% of these turtles had internal pathologies. The most common were hepatic lipidosis and chronic nephritis, which frequently co-occurred with each other or with pulmonary or pancreatic lesions. A high proportion of turtles were susceptible to infections caused by common bacteria in these habitats. We detected Herpesvirus, Mycoplasma spp. and more than 18 Gram-negative bacteria. The high prevalence of disease recorded in the two populations suggests that red-eared sliders are poorly suited to the conditions in their non-native range.