Sequence subtyping of <i>Trichomonas gallinae</i> from Bonelli’s eagle (<i>Aquila fasciata</i>) during four years (2014–2017) reveals that MLS type is associated with lesions

Avian trichomonosis is a parasitic disease that affects wild birds. The objective of this work was to determine the importance of avian trichomonosis in Bonelli’s eagles to improve conservation measures in this population. One hundred and eighty-eight birds were studied: 181 chicks, two juveniles, one subadult and four adults. The birds were externally examined and gross lesions at the oropharynx registered. Samples from the oropharyngeal cavity were obtained for <i>Trichomonas</i> spp. detection by culture and PCR, and positive samples were subjected to a multilocus sequence typing approach, including the ITS1/5.8S/ITS2 region (ITS), ribosomal RNA small subunit (18S) and Fe-hydrogenase gene (FeHyd). Global prevalence of <i>T. gallinae</i> infection was 37.8% in total, 45.5% in nestlings. Thirty-three percent of the birds developed lesions that ranged from mild (<i>n</i> = 41) to moderate (<i>n</i> = 14) or severe (<i>n</i> = 7). Multilocus sequence typing analysis showed five different MLS types, ITS-A/18S-VI/FeHyd-A1 and ITS-D/18S-II/Fe-C4 being the most frequent. An association between ITS-A/18S-VI/FeHyd-A1 and moderate or severe lesions was observed, but birds with type ITS-A/18S-VI/FeHyd-A2 also developed lesions. On the contrary, birds with MLS type ITS-D/18S-II/FeHyd-C4 displayed only a low proportion of mild lesions. Chicks raised in nests were at higher risk for <i>T. gallinae</i> infection and development of lesions than chicks raised in captivity. Discordances between samples cultured in TYM and samples subjected to PCR from oropharyngeal swabs were observed, swab-ITS-PCR being more sensitive. RESEARCH HIGHLIGHTS45.5% of Bonelli’s eagles in the nest carried <i>T. gallinae</i> and 39.4% showed lesions.PCR from oral swabs showed higher sensitivity than culture in TYM for detection of <i>T. gallinae</i>.MLS types ITS-A/18S-VI/Fe-A1 (and A2) are a risk factor for the development of lesions. 45.5% of Bonelli’s eagles in the nest carried <i>T. gallinae</i> and 39.4% showed lesions. PCR from oral swabs showed higher sensitivity than culture in TYM for detection of <i>T. gallinae</i>. MLS types ITS-A/18S-VI/Fe-A1 (and A2) are a risk factor for the development of lesions.

禽毛滴虫病（Avian trichomonosis）是一种感染野生鸟类的寄生虫病。本研究旨在明确禽毛滴虫病在波斑雕（Bonelli’s eagles）种群中的流行意义，以优化该种群的保护策略。

本研究共纳入188只波斑雕个体，其中包括181只雏鸟、2只幼鸟、1只亚成体以及4只成体。对所有受试个体进行外部检查，并记录其口咽部的肉眼病变情况。采集口咽部样本，通过培养法与聚合酶链式反应（PCR）检测毛滴虫属（Trichomonas spp.）感染；对于检测呈阳性的样本，采用多位点序列分型（MLS）方案进行分型，检测位点涵盖ITS1/5.8S/ITS2区域（ITS）、核糖体RNA小亚基（18S）以及铁氢化酶基因（FeHyd）。

全群鸽毛滴虫（T. gallinae）总感染率为37.8%，雏鸟感染率达45.5%。33%的受试个体出现口咽部病变，病变程度从轻（n=41）、中度（n=14）至重度（n=7）不等。多位点序列分型分析共检出5种不同的MLS型别，其中ITS-A/18S-VI/FeHyd-A1与ITS-D/18S-II/FeHyd-C4为最常见的型别。研究发现，ITS-A/18S-VI/FeHyd-A1型别与中、重度病变存在显著关联，而携带ITS-A/18S-VI/FeHyd-A2型别的个体同样出现了病变；与之相反，携带ITS-D/18S-II/FeHyd-C4型别的个体仅表现出低比例的轻度病变。巢内饲养的雏鸟相较于人工饲养的雏鸟，感染鸽毛滴虫以及出现口咽部病变的风险更高。本研究还观察到，TYM培养基培养法与咽拭子PCR检测结果存在不一致，其中咽拭子ITS-PCR的检测灵敏度更高。

【研究亮点】
1. 巢内波斑雕雏鸟中，45.5%携带鸽毛滴虫，39.4%出现口咽部病变；
2. 针对鸽毛滴虫的检测，口腔拭子PCR的灵敏度高于TYM培养基培养法；
3. MLS型别ITS-A/18S-VI/Fe-A1（及A2）是病变发生的风险因素。