Spatial Distribution and Host-Specific Patterns of Avian Haemosporidian Infections in a Semi-Arid Region of Northeastern Iran.

Abstract

Background: Avian haemosporidians (Haemoproteus, Plasmodium, and Leucocytozoon) and erythrocytic bacteria (e.g., Aegyptianella) are globally widespread, yet their epidemiology in Iran's semi-arid ecosystems remains understudied.

Objective: This study provides the first survey of avian blood parasites in Semnan Province, Iran, integrating microscopic and spatial analyses to identify host and environmental factors influencing infection patterns.

Methods: From September 2022 to December 2023, 263 healthy birds from ten species were examined. Giemsa-stained blood smears were screened microscopically. Infection hotspots and risk factors were identified using Kruskal-Wallis tests, logistic regression, and spatial mapping.

Results: Overall infection prevalence was 22.1% and was dominated by Haemoproteus spp. (18.6%), followed by Plasmodium spp. (1.5%), Leucocytozoon spp. (1.1%), and Aegyptianella spp. (0.8%). Pigeons exhibited the highest infection rate and were nearly three times more likely to be infected than other species (OR = 2.78, 95% CI: 1.38-5.60, p = 0.004). Spatial analysis revealed infection clustering in Shahroud County, which exhibits relatively higher humidity and vegetation cover compared with other parts of the predominantly semi‑arid Semnan Province. These findings highlight the potential influence of local climatic and ecological factors on the distribution of avian haemosporidian parasites. Although infection appeared slightly higher during spring and summer (9.6% and 7.3%, respectively) compared with autumn (3.4%) and winter (1.9%), the observed differences were not statistically significant (p > 0.05).

Conclusions: This baseline study provides important epidemiological data and establishes a framework for future molecular and vector‑based investigations of avian blood parasites in the Middle East.