Fatal parasite-induced enteritis and typhlocolitis in horses in Southern Brazil

Abstract Diseases related to the alimentary system are the main cause of death in horses. This retrospective study aimed to describe the pathological findings of fatal parasite-induced enteritis and typhlocolitis caused by cyathostominae, Eimeria leuckarti, Balantidium coli, and Strongyloides westeri in horses. The records of parasite-induced intestinal lesions in horses necropsied in Southern Brazil between 2005 and 2017 were reviewed. Ten horses had fatal parasitic enteritis and/or typhlocolitis, and the main causes were: cyathostominae typhlocolitis (6/10), E. leuckarti enteritis (1/10), S. westeri enteritis (1/10), B. coli colitis related to cyathostominae (1/10), and infection by multiple agents (1/10). Cyathostominae typhlocolitis showed marked mucosal thickening, with multifocal elevated nodules containing tangled filiform parasites. Microscopic examination revealed that the mucosa and submucosa had encysted parasitic structures surrounded by eosinophilic and granulomatous inflammation. E. leuckarti enteritis was microscopically characterized by macrogamonts, microgamonts, and oocysts inside the host cells. S. westeri enteritis showed microscopic atrophy of the villi with numerous mucosal encysted parasitic structures. B. coli typhlocolitis showed severe diffuse mucosal reddening, with microscopic superficial mucosal necrosis associated with multiple protozoan trophozoites. Fatal parasite-induced enteritis and typhlocolitis are important causes of death in horses in Southern Brazil.

摘要：消化系统疾病是马类死亡的首要病因。本回顾性研究旨在描述由圆线虫亚科（Cyathostominae）、莱氏艾美耳球虫（Eimeria leuckarti）、结肠小袋纤毛虫（Balantidium coli）和韦斯特斯类圆线虫（Strongyloides westeri）引发的致死性寄生虫性肠炎及盲肠结肠炎的病理特征。本研究回顾了2005年至2017年巴西南部地区经尸检的马类寄生虫性肠道病变档案记录。共计10匹马出现致死性寄生虫性肠炎和/或盲肠结肠炎，主要致病因素包括：圆线虫亚科相关性盲肠结肠炎（6/10）、莱氏艾美耳球虫性肠炎（1/10）、韦斯特斯类圆线虫性肠炎（1/10）、合并圆线虫亚科感染的结肠小袋纤毛虫性结肠炎（1/10），以及多病原体混合感染（1/10）。圆线虫亚科引发的盲肠结肠炎可见显著的黏膜增厚，伴随多灶性隆起结节，结节内可见缠绕成团的丝状寄生虫。镜下观察可见黏膜及黏膜下层存在包囊化的寄生虫结构，周围伴有嗜酸性粒细胞浸润及肉芽肿性炎症反应。莱氏艾美耳球虫性肠炎的镜下特征为宿主细胞内可见大配子体、小配子体及卵囊。韦斯特斯类圆线虫性肠炎可见绒毛显微萎缩，黏膜层内可见大量包囊化的寄生虫结构。结肠小袋纤毛虫性盲肠结肠炎可见严重的弥漫性黏膜发红，镜下可见浅表黏膜坏死，伴随大量原生动物滋养体。致死性寄生虫性肠炎及盲肠结肠炎是巴西南部地区马类死亡的重要病因。