Epidemiological and pathological aspects of salmonellosis in cattle in southern Brazil

ABSTRACT: Salmonellosis is a bacterial disease that affects several domestic animal species, and is commonly diagnosed in cattle, horses, and pigs. This study aimed to describe the epidemiological and pathological findings of eleven cases of enteric salmonellosis and two cases of salmonellosis with pulmonary involvement in cattle in Rio Grande do Sul State, Brazil. Clinical signs included fever, yellow diarrhea, sometimes with blood streaks, and dyspnea, with a clinical course ranging from 1 to 30 days. Eight cases occurred as outbreaks, whereas five cases occurred individually. Risk factors included inadequate handling practices, such as overcrowded facilities and comorbidities, including anaplasmosis. The main gross finding of the enteric presentation was fibrinonecrotic enterocolitis, occasionally associated with button ulcers, mesenteric lymphadenomegaly, splenomegaly, cholecystitis and hepatomegaly. In addition, one steer with a chronic clinical progression presented severe segmental thickening of the ileum, associated with intestinal rupture and peritonitis. In the respiratory system, the main findings were reddened, non-collapsed lungs, with multifocal areas of atelectasis. The main microscopic findings were observed in the small and large intestines, and these were characterized by severe necrosis and mucosal ulceration, associated with marked inflammatory infiltrate of neutrophils and fibrin deposition intermixed by rod-shaped bacterial aggregates, and fibrosis, as well as interstitial pneumonia. Seven cases yielded positive bacterial cultures for Salmonella spp. and three serovars, namely Typhimurium, Dublin, and Panama were identified. All cases exhibited immunolabeling for Salmonella spp. using immunohistochemistry.

摘要：沙门氏菌病（Salmonellosis）是一种可感染多种家养动物的细菌性疾病，在牛、马和猪中确诊病例较为常见。本研究旨在描述巴西南里奥格兰德州境内11例牛肠道沙门氏菌病以及2例伴肺部受累的牛沙门氏菌病的流行病学与病理学特征。临床症状表现为发热、黄色稀便（偶带血丝）以及呼吸困难，病程时长1至30天不等。其中8例为暴发疫情，5例为散发病例。危险因素包括饲养管理不当（如栏舍饲养密度过高）以及合并疾病（如无形体病）。肠道型病例的主要大体病理特征为纤维素性坏死性肠炎，偶伴纽扣状溃疡、肠系膜淋巴结肿大、脾脏肿大、胆囊炎以及肝脏肿大。此外，1例病程呈慢性的阉牛出现了严重的节段性回肠增厚，并发肠破裂与腹膜炎。呼吸系统病变的主要表现为肺脏发红、质地不塌陷，并可见多灶性肺不张区域。显微镜下的主要病变见于小肠与大肠，表现为严重的组织坏死与黏膜溃疡，伴随显著的中性粒细胞炎性浸润、纤维素沉积（其间混有杆状细菌集落）以及纤维化，同时可见间质性肺炎。7例样本的沙门氏菌属（Salmonella spp.）细菌培养结果呈阳性，且鉴定出3种血清型：鼠伤寒沙门氏菌（Typhimurium）、都柏林沙门氏菌（Dublin）以及巴拿马沙门氏菌（Panama）。所有病例均通过免疫组织化学检测呈现沙门氏菌属阳性免疫标记。