Curtis-Robles Rachel, Lewis Barbara C, Hamer Sarah A
College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, 4458 TAMU, College Station, TX 77843, USA.
Texas A&M Veterinary Medical Diagnostic Laboratory, P.O. Drawer 3040, College Station, TX 77841-3040, USA.
Int J Parasitol Parasites Wildl. 2016 Apr 12;5(2):117-23. doi: 10.1016/j.ijppaw.2016.04.001. eCollection 2016 Aug.
Infection with the zoonotic vector-borne protozoal parasite Trypanosoma cruzi causes Chagas disease in humans and dogs throughout the Americas. Despite the recognized importance of various wildlife species for perpetuating Trypanosoma cruzi in nature, relatively little is known about the development of cardiac disease in infected wildlife. Using a cross-sectional study design, we collected cardiac tissue and blood from hunter-donated wildlife carcasses- including raccoon (Procyon lotor), coyote (Canis latrans), gray fox (Urocyon cinereoargenteus), and bobcat (Lynx rufus) - from central Texas, a region with established populations of infected triatomine vectors and increasing diagnoses of Chagas disease in domestic dogs. Based on PCR analysis, we found that 2 bobcats (14.3%), 12 coyotes (14.3%), 8 foxes (13.8%), and 49 raccoons (70.0%) were positive for T. cruzi in at least one sample (right ventricle, apex, and/or blood clot). Although a histologic survey of right ventricles showed that 21.1% of 19 PCR-positive hearts were characterized by mild lymphoplasmocytic infiltration, no other lesions and no amastigotes were observed in any histologic section. DNA sequencing of the TcSC5D gene revealed that raccoons were infected with T. cruzi strain TcIV, and a single racoon harbored a TcI/TcIV mixed infection. Relative to other wildlife species tested here, our data suggest that raccoons may be important reservoirs of TcIV in Texas and a source of infection for indigenous triatomine bugs. The overall high level of infection in this wildlife community likely reflects high levels of vector contact, including ingestion of bugs. Although the relationship between the sylvatic cycle of T. cruzi transmission and human disease risk in the United States has yet to be defined, our data suggest that hunters and wildlife professionals should take precautions to avoid direct contact with potentially infected wildlife tissues.
感染人畜共患的媒介传播原生动物寄生虫克氏锥虫会在美洲各地的人类和犬类中引发恰加斯病。尽管人们认识到各种野生动物物种对于克氏锥虫在自然界中的持续存在具有重要意义，但对于受感染野生动物中心脏病的发展情况却知之甚少。我们采用横断面研究设计，从得克萨斯州中部猎人捐赠的野生动物尸体中采集了心脏组织和血液，这些野生动物包括浣熊（北美浣熊）、郊狼（丛林狼）、灰狐（灰狐）和山猫（短尾猫），该地区已存在受感染的锥蝽媒介种群，且家犬中恰加斯病的诊断病例不断增加。基于聚合酶链反应（PCR）分析，我们发现至少一个样本（右心室、心尖和/或血凝块）中，2只山猫（14.3%）、12只郊狼（14.3%）、8只狐狸（13.8%）和49只浣熊（70.0%）的克氏锥虫呈阳性。尽管对右心室的组织学检查显示，19个PCR阳性心脏中有21.1%的特征为轻度淋巴细胞浆细胞浸润，但在任何组织学切片中均未观察到其他病变和无鞭毛体。TcSC5D基因的DNA测序显示，浣熊感染了克氏锥虫TcIV株，且有一只浣熊同时感染了TcI/TcIV混合感染。相对于此处测试的其他野生动物物种，我们的数据表明，浣熊可能是得克萨斯州TcIV的重要储存宿主，也是本地锥蝽的感染源。这个野生动物群落中总体较高的感染水平可能反映了与媒介的高接触程度，包括吞食锥蝽。尽管美国克氏锥虫传播的野生动物循环与人类疾病风险之间的关系尚未明确，但我们的数据表明，猎人及野生动物专业人员应采取预防措施，避免直接接触可能受感染的野生动物组织。
