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）是一种影响全球数百万人口的被忽视疾病，在马拉尼昂州（Maranhão）流行广泛。本研究共对225只采自马拉尼昂西部低地的南美沟齿鼠（Holochilus sciureus）进行检测，其中144只（占比64%）的粪便样本中检出血吸虫卵。肉眼观察可见肝脏与脾脏表面存在边界清晰的白色病灶。组织病理学检查显示，食管、肝脏、脾脏、胰腺及十二指肠内可见多灶性肉芽肿，其内可见与曼氏血吸虫（Schistosoma mansoni）卵形态相符的结构；同时存在严重的肝内多灶融合性微空泡变性，伴随散在胆管增生以及纤维化区域相关的上皮增生。在门静脉间隙的血管内可观察到该寄生虫的成虫形态。肺部呈现中度弥漫性间质性肺炎，病灶内存在曼氏血吸虫卵。肾脏肾盂内可见透明管型，同时伴随弥漫性出血。综上，南美沟齿鼠呈现出与人类相似的病理特征，该啮齿类动物可作为马拉尼昂低地（Baixada Maranhense）的哨兵物种。