Trypanosoma species (Trypanosomatida, Kinetoplastea) are almost exclusively heteroxenous flagellated parasites, which have been extensively studied as the causative agents of severe trypanosomiasis in humans and domestic animals. However, the biology of avian trypanosomes remains insufficiently known, particularly in wildlife, despite information that some species might be pathogenic and affect the fitness of intensively infected individuals. Avian trypanosomes are cosmopolitans. Due to regular bird seasonal migrations, this host–parasite system might provide new insight for better understanding mechanisms of transcontinental dispersal of pathogens, their ecological plasticity, specificity and speciation. Trypanosoma everetti parasitizes numerous bird species globally, but data on its biology are scarce and its vectors remain unknown. This study aimed to test experimentally whether widespread Culicoides (Diptera: Ceratopogonidae) biting midges are susceptible to infection with this parasite. Two common house martins Delichon urbicum and two sedge warblers Acrocephalus schoenobaenus naturally infected with T. everetti were caught in the wild after arrival from African wintering grounds. Laboratory reared Culicoides nubeculosus and wild-caught Culicoides impunctatus biting midges were exposed by allowing them to take infected blood meals. The experimentally infected and control insects were maintained in the laboratory and dissected at intervals to follow the development of the parasite. Infections were determined using microscopic examination and PCR-based testing. Four closely related haplotypes of T. everetti were found, and each was present in different individual parasite-donor birds. These parasites readily developed and produced metacyclic trypomastigotes in C. nubeculosus and C. impunctatus biting midges. Molecular characterisation of T. everetti was developed. According to Bayesian phylogenetic analysis using a DNA fragment encoding 18S rRNA, the five species of small avian trypanosomes were closely related. Wild caught Culicoides biting midges were also collected and screened for the presence of natural infections. In all, 6.8% of wild-caught biting midges belonging to five Culicoides species were PCR-positive for kinetoplastids, including Trypanosoma species. Culicoides biting midges are readily susceptible and likely naturally transmit avian trypanosomes and thus, should be targeted in epidemiology research of avian trypanosomiasis.

锥虫物种（Trypanosomatida，Kinetoplastea）几乎完全是异种鞭毛寄生虫，已被广泛研究为人类和家畜中严重锥虫病的病原体。然而，鸟类锥虫的生物学仍然知之甚少，特别是在野生动物中，尽管有信息表明某些物种可能是致病的并影响密集感染个体的健康。鸟类锥虫是世界性的。由于定期的鸟类季节性迁徙，这种宿主-寄生虫系统可能为更好地理解病原体跨大陆传播机制、其生态可塑性、特异性和物种形成提供新的见解。锥虫在全球范围内寄生于众多鸟类，但有关其生物学的数据很少，其传播媒介仍然未知。这项研究旨在通过实验测试广泛分布的Culicoides（双翅目：Ceratopogonidae）咬蠓是否容易感染这种寄生虫。从非洲越冬地抵达后，在野外捕获了两只自然感染了T. everetti的普通家燕Delichon urbicum和两只莎草莺Acrocephalus schoenobaenus 。实验室饲养的Culicoides nubeculosus和野生捕获的Culicoides impunctatus叮咬的蠓通过让它们吃受感染的血粉而暴露出来。实验性感染和对照昆虫保持在实验室中，并每隔一段时间进行解剖以跟踪寄生虫的发展。使用显微镜检查和基于 PCR 的测试确定感染。发现了四种密切相关的T. everetti单倍型，每一种都存在于不同的寄生虫供体鸟类中。这些寄生虫很容易在C. nubeculosus和C. impunctatus咬蠓中发育并产生亚环状锥体。T. everetti的分子表征发展了。根据使用编码 18S rRNA 的 DNA 片段的贝叶斯系统发育分析，五种小型鸟类锥虫密切相关。还收集了野生捕获的Culicoides咬蠓并筛选了自然感染的存在。总共有 6.8% 的野生捕捞蠓属于 5种库蠓科动物，包括锥虫属的动质体 PCR 阳性。Culicoides咬蠓很容易感染并很可能自然传播禽锥虫，因此，应将其作为禽锥虫病流行病学研究的目标。