Contribution of host species and pathogen clade to snake fungal disease hotspots in Europe

Abstract 1. Infectious diseases are influenced by interactions between host and pathogen, and are rarely homogenous across the landscape. Areas with elevated pathogen prevalence maintain a high force of infection, can facilitate pathogen spread to new regions, and may indicate areas with impacts on host populations. However, isolating the ecological processes that result in increases in infection prevalence and intensity remains a challenge. 2. Here we elucidate the contribution of pathogen clade and host species in disease hotspots of Ophidiomyces ophidiicola, the pathogen that causes snake fungal disease, in 21 species of snakes infected with multiple pathogen strains across 10 countries in Europe. 3. We found isolated areas of disease hotspots in a landscape where infections were otherwise low. O. ophidiicola clade had important effects on transmission, and areas with multiple pathogen clades had higher host infection prevalence. Snake species identity further influenced infection, with most positive detections coming from the Natrix genus. Most species present in the community only experienced increased levels of infection when multiple strains were present. However, one species, N. tessellata , appeared highly susceptible, having increased infection prevalence regardless of pathogen strain, indicating that this species may be important in pathogen maintenance. 4. Our results suggest that both host and pathogen identity are essential components contributing to increased pathogen prevalence. More broadly, our findings indicate that coevolutionary relationships between hosts and pathogens may be key mechanisms explaining variation in landscape patterns of disease.