Alberto Soriano Graduate School, Faculty of Agronomy, UBA, Buenos Aires, Argentina.
Prev Vet Med. 2011 Feb 1;98(2-3):133-41. doi: 10.1016/j.prevetmed.2010.10.006. Epub 2010 Nov 10.
The recurrence and persistence of foot and mouth disease (FMD) could be the consequence of cyclic and massive transportation of calves. For this reason, in South America, vaccination strategies related to livestock dynamic are being promoted. In order to aid the evaluation of such strategies, a method for predicting the risk of transportation of nonvaccinated weaned calves was developed; this method combines expert opinion and empirical evidence using Bayesian estimators. It was applied through Monte Carlo simulation to data of Argentina under four hypothetical vaccination schemes: E1, extended vaccination season of 1/6 of the population of calves each month from July to December without second round vaccination (SRV); E2, extended irregular vaccination from July to December with SRV applied to 70% of the calves resembling the scheme applied in Argentina in 2001; E3, vaccination in November and December without SRV; and E4, vaccination concentrated in November. E1 resulted in probability of transporting non vaccinated calves (tnvc) reaching its maximum in the following year in May with mean=0.0250 and percentile 95% (P95)=0.0404; for the same month tnvc estimates for the other schemes were E2: mean=0.0071; P95=0.0162; E3: mean=0.0017; P95=0.0042 and E4: mean=0.0001; P95=0.0004. Bonferroni multiple comparison for simultaneous assertions for May showed that E4 resulted the best scheme, E1 the worst, and E2 and E3 are intermediate with nonsignificant difference observed between overall (p<0.05). Results were consistent with historical records and quantification for future needs for re-vaccination was made possible. While the ratio "total vaccinated"/"total estimated existences" will give a biased vision of vaccination coverage under the situation of extended vaccination campaigns, a model as the one developed here could allow a more accurate assessment and the design of mitigation plans.
口蹄疫（FMD）的复发和持续存在可能是由于小牛的周期性和大规模运输造成的。出于这个原因，在南美洲，正在推广与牲畜动态相关的疫苗接种策略。为了帮助评估这些策略，开发了一种预测未接种断奶小牛运输风险的方法；该方法结合了贝叶斯估计器的专家意见和经验证据。它通过蒙特卡罗模拟应用于阿根廷的数据，根据四种假设的疫苗接种方案：E1，从 7 月到 12 月，每月对 1/6 的小牛人口进行延长疫苗接种季节，没有第二轮疫苗接种（SRV）；E2，从 7 月到 12 月进行不规律的延长疫苗接种，对 70%的小牛进行 SRV，类似于 2001 年在阿根廷实施的计划；E3，11 月和 12 月不接种疫苗；E4，集中在 11 月接种疫苗。E1 导致未接种疫苗的小牛（tnvc）在次年 5 月达到最大值，平均值为 0.0250，95%百分位数（P95）为 0.0404；对于同月的其他方案，tnvc 估计值为 E2：平均值=0.0071；P95=0.0162；E3：平均值=0.0017；P95=0.0042 和 E4：平均值=0.0001；P95=0.0004。5 月同时断言的 Bonferroni 多重比较表明，E4 是最好的方案，E1 是最差的方案，E2 和 E3 是中间方案，总体上没有观察到差异（p<0.05）。结果与历史记录一致，并为未来重新接种疫苗的需求进行了量化。虽然在延长疫苗接种活动的情况下，“总接种人数”与“总估计存在人数”的比例将对口蹄疫疫苗接种覆盖率产生偏差，但像这里开发的模型可以进行更准确的评估和制定缓解计划。
