Determinants of avian malaria prevalence in mountainous Transcaucasia

Abstract

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 offactors responsiblefor 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 offactors 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.

Robust geographical determinants of infection prevalence and a contrasting latitudinal diversity gradient for haemosporidian parasites in Western Palearctic birds

“…Again, such studies have been instrumental to improving our understanding of natural variation in parasite prevalence. However, these previous haemosporidian community analyses have failed to identify landscape predictors that scale across parasite genera (Atoyan et al., 2018; Barrow et al., 2019; Clark & Clegg, 2017; Harvey & Voelker, 2019; Loiseau et al., 2010; Lutz et al., 2015), hampering our ability to make general predictions about possible changes in prevalence in future scenarios. This is a major hindrance to the development of harmonized, biologically relevant models that can be used to explore how uncertainties can be reduced to make predictions more useful.…”

The drivers of avian‐haemosporidian prevalence in tropical lowland forests of New Guinea in three dimensions

“…NDVI was calculated using the following equation NDVI = (NIR − RED)/(NIR + RED), where NIR is the near‐infrared and RED the visible band (Myneni et al, 1995 ). It measures the degree of absorption by chlorophyll in red wavelengths (Myneni et al, 1995 ), the index values fall between −1 and 1, with values around −1 representing clouds and water, values around 0 representing bare soil, and values close to 1 representing forested areas with maximum greenness (i.e., forest cover) (Atoyan et al, 2018 ). For environmental variables that had a low resolution for the exact GPS coordinate, we used the value of the adjacent pixel (<800 m from the original point) to that locality.…”

“…Associations between birds, haemosporidian parasites, and dipteran vectors are governed by both biotic (e.g., host availability and density) and abiotic (e.g., temperature and precipitation) factors (Chapa‐Vargas et al, 2020 ), in addition to anthropogenic alterations, such as deforestation and habitat degradation (Atoyan et al, 2018 ; Chasar et al, 2009 ; Marzal et al, 2015 ; Olsson‐Pons et al, 2015 ; Sehgal, 2010 ). Temperature, humidity, precipitation and proximity to water appear to be the most important environmental variables influencing avian‐haemosporidian interactions on regional and global scales (Illera et al, 2017 ; Jones et al, 2013 ; Mendenhall et al, 2013 ; Padilla et al, 2017 ; Villar Couto et al, 2019 ).…”