Determinants of avian malaria prevalence in mountainous Transcaucasia

Deforestation, urban development, and global climate change can lead to dramatic changes of ecological communities and increase prevalence of infectious diseases at higher latitudes and altitudes. Identification of factors responsible for the prevalence of parasites is of crucial importance to understand the dynamics of parasite distribution in a changing environment. Mountain areas are especially suitable for studies of factors governing parasite distribution and prevalence due to heterogeneity of landscapes, climatic regimes, and other biotic and abiotic conditions. We examined 903 avian blood smears collected in mountains of Transcaucasia for prevalence of Haemoproteus and Plasmodium. We found that the haemoparasites prevalence differed among bird species and localities, highlighting the environmental components affecting disease distribution. The prevalence of both Haemoproteus and Plasmodium was significantly higher in males, adults, and migratory species than in females, juveniles, and resident species. Geographic Information System (GIS) and linear regression analyses revealed that elevation and monthly average precipitation were strongly correlated with proportion of infected birds with Plasmodium, indicating that the prevalence increased with increase of monthly average temperature and elevation. Birds from forested and high grassed areas were also more infected with avian haemosporidia. Our study provides baseline data for modelling of parasites distribution under global climate change scenarios, which is of great importance for monitoring and management of communities and environment for conservation and human health.