Assessing the variability in transmission of bovine tuberculosis within Spanish cattle herds
Assessing the variability in transmission of bovine tuberculosis within Spanish cattle herds
复制标题
DOI：
10.1016/j.epidem.2018.01.003
复制
发表时间：
2018-06-01
期刊：
影响因子：
3.8
通讯作者：
Napp, S.
中科院分区：
文献类型：
--
作者：
Ciaravino, G.;Garcia-Saenz, A.;Napp, S.
在西班牙，尽管多年来一直努力根除牛结核病，但该病仍然是地方病，在某些地区流行率很高。在这种情况下，监测和控制计划可能需要重新评估，了解西班牙牛群中bTB传播的动态可能有助于制定新的战略，以减少检测感染牛群的时间，并从已经感染的牛群中消除bTB。在这里，我们开发了一个房室随机模型来模拟bTB的畜群内传播，并将来自22个畜群的流行病学数据输入模型（从以前的工作中获得），并使用近似贝叶斯计算方法进行参数推断。我们还估计了“畜群内传播潜力数”（R-h），即，考虑到控制频率不同的情况，将感染的单个动物引入完全易感的畜群产生的继发病例的平均数量。获得的传输参数的中位全局值为：对于传播系数（β），0.014只新感染动物/感染个体/天（即每年5.2），受感染者变为传染性的速率（α）为每天0.01（相当于97天的潜伏期），以及受感染个体对皮肤试验产生反应的速率（α（1）），0.08/天（相当于感染动物发生反应的12天时间）。然而，结果也证明了22个牛群中这些参数（特别是β和α）的估计值存在很大差异。考虑到测试之间的6个月间隔，平均R-h为0.23，间隔1年增加到0.82，测试间隔2年和4年分别增加到2.01和3.47。
In Spain, despite years of efforts to eradicate bovine tuberculosis (bTB), the disease is still endemic, with some areas of high prevalence. In this context, the surveillance and control plans may need to be re-evaluated, and understanding the dynamics of bTB spread within Spanish herds may help to develop new strategies for reducing the time for detection of infected herds and for the elimination of bTB from the herds already infected. Here, we developed a compartmental stochastic model to simulate bTB within-herd transmission, fed it with epidemiological data from 22 herds (obtained from a previous work) and carried out parameter inference using Approximate Bayesian Computing methods We also estimated the "Within-herd transmission potential Number" (R-h), i.e. the average number of secondary cases generated by a single animal infected introduced into a totally susceptible herd, considering different scenarios depending on the frequency of controls. The median global values obtained for the transmission parameters were: for the transmission coefficient (beta), 0.014 newly infected animals per infectious individual per day (i.e. 5.2 per year), for the rate at which infected individuals become infectious (alpha), 0.01 per day (equivalent to a latent period of 97 days), and for the rate at which infected individuals become reactive to the skin test (alpha(1)), 0.08 per day (equivalent to a period of 12 days for an infected animal to become reactive). However, the results also evidenced a great variability in the estimates of those parameters (in particular beta and alpha) among the 22 herds. Considering a 6-month interval between tests, the mean R-h was 0.23, increasing to 0.82 with an interval of 1 year, and to 2.01 and 3.47 with testing intervals of 2 and 4 years, respectively.