Global prevalence of haemosporidian parasites in wild birds: Systematic review and meta-analysis

Abstract

Haemosporidians (Plasmodium, Haemoproteus, and Leucocytozoon) are blood parasites that infect birds and other vertebrates worldwide. Infections can cause disease that reduces survival and reproductive success, and may even lead to mortality. They are primarily assessed through prevalence, a population parameter that varies among species, regions, and seasons due to environmental and ecological factors. Although meta-analyses on this parameter exist, none globally synthesize data across the three haemosporidian genera and current detection methods (PCR and microscopy). The objective of this systematic review was to determine the overall prevalence of haemosporidian parasites in wild birds distributed across different zoogeographic regions. The review was conducted following the methodology proposed by the Joanna Briggs Institute (JBI) for scoping reviews and was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) to estimate pooled prevalence and assess variation according to diagnostic method, continent, parasite genus, and bird family. The global pooled prevalence was 12.3%, with estimates of 12.1% by PCR and 13.1% by microscopy. Regardless of the diagnostic method, the continents with the highest prevalence were Africa (P_MIC = 22.3%; P_PCR = 13.5%) and Europe (P_MIC = 28.6%; P_PCR = 12.6%). The high heterogeneity among studies suggests that multiple biological, environmental, and methodological factors contribute to global variation in infection patterns. This study provides the first global reference of haemosporidian parasite prevalence in wild birds and highlights the need for standardized reporting of environmental and methodological variables to better understand the drivers of avian malaria dynamics.