Prevalence Patterns of Avian Plasmodium and Haemoproteus Parasites and the Influence of Host Relative Abundance in Southern China

Infectious diseases threaten the health and survival of wildlife populations. Consequently, relationships between host diversity, host abundance, and parasite infection are important aspects of disease ecology and conservation research. Here, we report on the prevalence patterns of avian Plasmodium and Haemoproteus infections and host relative abundance influence based on sampling 728 wild-caught birds representing 124 species at seven geographically widespread sites in southern China. The overall prevalence of two haemoprotozoan parasites, Plasmodium and Haemoproteus, was 29.5%, with 22.0% attributable to Haemoproteus and 7.8% to Plasmodium. Haemoproteus prevalence differed significantly among different avian host families, with the highest prevalence in Nectariniidae, Pycnonotidae and Muscicapidae, whereas Plasmodium prevalence varied significantly among host species. Seventy-nine mitochondrial lineages including 25 from Plasmodium and 54 from Haemoproteus were identified, 80% of which were described here for the first time. The phylogenetic relationships among these parasites indicated stronger host-species specificity for Haemoproteus than Plasmodium. Well-supported host-family (Timaliidae) specific clades were found in both Plasmodium and Haemoproteus. The Haemoproteus tree shows regional subclades, whereas the Plasmodium clades are “scattered” among different geographical regions. Interestingly, there were statistically significant variations in the prevalence of Plasmodium and Haemoproteus among the geographical regions. Furthermore, the prevalence of Plasmodium and Haemoproteus were not significantly correlated with host relative abundance. Further efforts will focus on exploring the relationships between parasite prevalence and sex, age, and immune defense of the host.传染病威胁野生动物种群的健康与存续。因此，宿主多样性、宿主丰度与寄生虫感染之间的关联，是疾病生态学与保护生物学研究的重要议题。本研究基于在中国南方7个分布广泛的地理点位采集的728只野生捕获鸟类（涵盖124个物种），报道了禽疟原虫（Plasmodium）与血变原虫（Haemoproteus）的感染流行模式，以及宿主相对丰度的影响。两种血孢子虫——疟原虫与血变原虫的总体感染率为29.5%，其中血变原虫感染占比22.0%，疟原虫感染占比7.8%。血变原虫的感染率在不同鸟类宿主科间存在显著差异，其中以太阳鸟科（Nectariniidae）、鹎科（Pycnonotidae）以及鹟科（Muscicapidae）的感染率最高；而疟原虫的感染率则在不同宿主物种间存在显著差异。本研究共鉴定出79个线粒体谱系，其中25个属于疟原虫、54个属于血变原虫，其中80%的谱系为首次报道。这些寄生虫的系统发育关系显示，血变原虫相较于疟原虫具有更强的宿主物种特异性。疟原虫与血变原虫中均发现了支持度较高的宿主科（画眉科Timaliidae）特异性演化支。血变原虫的系统发育树呈现出地理亚支结构，而疟原虫的演化支则在不同地理区域间呈“散在分布”状态。值得注意的是，不同地理区域间的疟原虫与血变原虫感染率存在统计学意义上的显著差异。此外，疟原虫与血变原虫的感染率与宿主相对丰度未呈现显著相关性。后续研究将进一步探讨寄生虫感染率与宿主性别、年龄及免疫防御能力之间的关联。