Department of Population Health and Pathobiology, North Carolina State University, College of Veterinary Medicine, Raleigh, NC, USA.
Laboratory of Veterinary Epidemiology (Epilab), Department of Preventive Veterinary Medicine, Universidade Federal do Rio Grande do Sul, RS, Brazil.
Prev Vet Med. 2021 May;190:105319. doi: 10.1016/j.prevetmed.2021.105319. Epub 2021 Mar 3.
Equine infectious anemia virus (EIAV) is a transboundary disease affecting a large number of equines worldwide. In this study, we assessed the transmission risk of EIAV in Rio Grande do Sul, Brazil. Serum samples from 1010 animals from 341 farms were initially analyzed using agar gel immunodiffusion to detect viral antibodies, and no antibody-positive animals were found. A risk assessment stochastic model was applied to generate the expected number of potential infections per month and to estimate the time to new infections. Our results estimated 6.5 months as the interval for new infections in the worst-case scenario. Among the variables evaluated, the number of transported animals and the test sensitivity influenced the model the most. These results were then used to revisit the impact of EIAV control regulations, which triggered a change in the diagnostic testing required for animal movement, in which the validity of a negative test for EIAV was extended from 60 to 180 days. Finally, revisiting the annual average of infected farms before and after the new regulation, the number of infected farms increased pre-implementation, and then, the number of culled animals increased, which should impact future EIAV incidence in this region. Our results demonstrated the importance of constant reviews of disease control programs and provided quantitative-based knowledge for decision-makers in official veterinary services.
马传染性贫血病毒（EIAV）是一种影响全球大量马属动物的跨境疾病。在本研究中，我们评估了巴西南里奥格兰德州 EIAV 的传播风险。使用琼脂凝胶免疫扩散法对来自 341 个农场的 1010 份动物血清样本进行了初步分析，以检测病毒抗体，但未发现抗体阳性动物。应用风险评估随机模型来生成每月潜在感染的预期数量，并估计新感染的时间。我们的结果估计在最坏情况下，新感染的间隔为 6.5 个月。在所评估的变量中，运输动物的数量和检测灵敏度对模型的影响最大。然后，将这些结果用于重新评估 EIAV 控制法规的影响，该法规引发了动物流动所需诊断检测的变化，其中 EIAV 阴性检测的有效期从 60 天延长至 180 天。最后，在新规定前后重新审视每年感染农场的平均数量，实施前感染农场的数量增加，然后被扑杀动物的数量增加，这将影响该地区未来 EIAV 的发病率。我们的结果表明了对疾病控制计划进行持续审查的重要性，并为官方兽医服务的决策者提供了基于定量的知识。
