Fasciolosis is a food-borne disease that causes great distress to a range of hosts, including humans. The objectives of this study were to (1) evaluate the liver damage and carcass weight of cattle naturally infected with Fasciola hepatica from the state of Rio Grande do Sul (RS), Brazil, and to (2) determine the distribution of adult flukes in 12,236 cattle liver from RS. The data from these experiments were used to calculate the overall economic loss due to F. hepatica infection. Eighteen adult Polled Hereford cows were divided into a triclabendazole (TbG) and a F. hepatica-positive group (FhG). For Experiment 1, a generalized linear mixed model revealed a statistical difference in carcass weight (49.8 kg) between TbG and FhG. The Monte Carlo analysis also revealed that the animals’ weight differences were due to the disease. For Experiment 2, the prevalence of infected livers was above 16% (1904/12,236), mostly (20.1%) from the south-west region of RS. The Susceptible-infected-recovered (SIR) epidemic model revealed the evolution of the infection using a high infectivity and low recovery rate. Other distinctive scenarios that occur in RS were also established with different rates of infectivity. The economic assessment showed a potential loss of US$45 million to the beef cattle industry of RS, with an overall State cost of US$90.3 million. These novel findings reveal the importance of fasciolosis infection, which can cause a significant health condition and poor animal welfare.

中文翻译：

---

牛肝片形吸虫感染和流行区模拟模型的使用

片形吸虫病是一种食源性疾病，会给包括人类在内的一系列宿主带来极大的痛苦。本研究的目的是 (1) 评估自然感染牛的肝损伤和胴体重量。肝片状吸虫来自巴西南里奥格兰德州 (RS) 和 (2) 确定了来自 RS 的 12,236 只牛肝中成年吸虫的分布。这些实验的数据被用来计算由于以下原因造成的总体经济损失F.肝感染。将 18 头 Polled Hereford 成年奶牛分为三氯苯达唑 (TbG) 和F.肝-阳性组（FhG）。对于实验 1，广义线性混合模型显示 TbG 和 FhG 之间的胴体重量 (49.8 kg) 存在统计学差异。蒙特卡洛分析还显示，动物的体重差异是由于疾病造成的。对于实验 2，感染肝脏的患病率高于 16% (1904/12,236)，主要 (20.1%) 来自 RS 西南地区。易感感染恢复 (SIR) 流行模型揭示了使用高传染性和低恢复率的感染演变。RS 中发生的其他独特场景也具有不同的感染率。经济评估显示，RS 的肉牛产业可能损失 4500 万美元，国家总成本为 9030 万美元。这些新发现揭示了片形吸虫感染的重要性，