Parasitological and histological aspects of Holochilus sciureus naturally infected by Schistosoma mansoni

Abstract Schistosomiasis is a neglected disease that affects millions of people around the world, being common in the state of Maranhão. A total of 225 rodents of the Holochilus sciureus species from the Western Lowland Maranhão were studied, of which 144 animals (64%) exhibited Schistosoma eggs in their feces samples. Macroscopic lesions characterized as well-defined whitish areas on the liver and spleen surfaces were observed. Histopathological examination revealed multifocal granulomas in the esophagus, liver, spleen, pancreas and duodenum, with structures compatible with Schistosoma mansoni eggs, as well as severe hepatic micro-vacuolar degeneration, multifocal and coalescent, with proliferation of random bile ducts and associated epithelial hyperplasia to areas of fibrosis. Adult forms of the parasite were observed in the blood vessels of the portal space. The lungs exhibited moderate and diffuse interstitial pneumonia with intralesional S. mansoni eggs. In the kidneys, hyaline cylinders were observed in the pelvis and diffuse hemorrhage. In conclusion, H. sciureus displays a pathological picture similar to human being. This rodent plays a role as sentinel in Baixada Maranhense.

摘要 血吸虫病（Schistosomiasis）是一种被忽视的传染病，全球有数百万民众受其影响，在巴西马拉尼昂州尤为流行。本研究共分析了采自马拉尼昂州西部低地的225只赤拟髯鼠（Holochilus sciureus），其中144只（占比64%）的粪便样本中检出了血吸虫虫卵。肉眼观察可见肝脏与脾脏表面存在边界清晰的白色病灶区域。组织病理学检查显示，食管、肝脏、脾脏、胰腺及十二指肠内存在多灶性肉芽肿，其结构与曼氏血吸虫（Schistosoma mansoni）虫卵相符；同时可见严重的肝脏微空泡变性，呈多灶性且相互融合，伴随随机分布的胆管增生，以及纤维化区域相关的上皮增生。在门脉区血管内可见该寄生虫的成虫形态。肺部可见中度弥漫性间质性肺炎，病灶内存在曼氏血吸虫虫卵。肾脏肾盂内可见透明管型，同时存在弥漫性出血。综上，赤拟髯鼠的病理表现与人类感染者高度相似，该啮齿动物可作为马拉尼昂低地（Baixada Maranhense）地区血吸虫病的哨兵动物。