Royal Veterinary College, London AL9 7TA, United Kingdom.
Prev Vet Med. 2013 Jun 1;110(2):88-102. doi: 10.1016/j.prevetmed.2013.02.010. Epub 2013 Mar 13.
Post-weaning multi-systemic wasting syndrome (PMWS) is a multi-factorial disease with major economic implications for the pig industry worldwide. The present study aimed to assess the economic impact of PMWS and porcine circovirus type 2 (PCV2) subclinical infections (PCV2SI) for farrow-to-finish farms and to estimate the resulting cost to the English pig industry. A disease model was built to simulate the varying proportions of pigs in a batch that get infected with PCV2 and develop either PMWS, subclinical disease (reduce growth without evident clinical signs) or remain healthy (normal growth and no clinical signs), depending on the farm level PMWS severity. This PMWS severity measure accounted for the level of post-weaning mortality, PMWS morbidity and proportion of PCV2 infected pigs observed on farms. The model generated six outcomes: infected pigs with PMWS that die (PMWS-D); infected pigs with PMWS that recover (PMWS-R); subclinical pigs that die (Sub-D); subclinical pigs that reach slaughter age (Sub-S); healthy pigs sold (H-S); and pigs, infected or non-infected by PCV2, that die due to non-PCV2 related causes (nonPCV2-D). Enterprise and partial budget analyses were used to assess the deficit/profits and the extra costs/extra benefits of a change in disease status, respectively. Results from the economic analysis at pig level were combined with the disease model's estimates of the proportion of different pigs produced at different severity scores to assess the cost of PMWS and subclinical disease at farm level, and these were then extrapolated to estimate costs at national level. The net profit for a H-S pig was £19.2. The mean loss for a PMWS-D pig was £84.1 (90% CI: 79.6-89.1), £24.5 (90% CI: 15.1-35.4) for a PMWS-R pig, £82.3 (90% CI: 78.1-87.5) for a Sub-D pig, and £8.1 (90% CI: 2.18-15.1) for a Sub-S pig. At farm level, the greatest proportion of negative economic impact was attributed to PCV2 subclinical pigs. The economic impact for the English pig industry for the year 2008, prior to the introduction of PCV2 vaccines, was estimated at £52.6 million per year (90% CI: 34.7-72.0), and approximately £88 million per year during the epidemic period. This was the first study to use empirical data to model the cost of PMWS/PCV2SI at different farm severity levels. Results from this model will be used to assess the efficiency of different control measures and to provide a decision support tool to farmers and policy makers.
断奶后多系统消耗综合征（PMWS）是一种多因素疾病，对全球养猪业具有重大的经济影响。本研究旨在评估 PMWS 和猪圆环病毒 2 型（PCV2）亚临床感染（PCV2SI）对分娩至育肥农场的经济影响，并估计对英国养猪业的相关成本。建立了一种疾病模型来模拟批量感染 PCV2 的猪的不同比例，并根据农场的 PMWS 严重程度发展为 PMWS、亚临床疾病（生长减少但无明显临床症状）或保持健康（正常生长且无临床症状）。该 PMWS 严重程度衡量标准考虑了断奶后死亡率、PMWS 发病率和农场观察到的 PCV2 感染猪的比例。该模型产生了六个结果：患有 PMWS 并死亡的感染猪（PMWS-D）；患有 PMWS 并康复的感染猪（PMWS-R）；死于亚临床疾病的感染猪（Sub-D）；达到屠宰年龄的亚临床猪（Sub-S）；出售的健康猪（H-S）；以及因非 PCV2 相关原因而死亡的感染或未感染 PCV2 的猪（非 PCV2-D）。企业和部分预算分析分别用于评估疾病状态变化的亏损/利润和额外成本/额外收益。然后将猪水平经济分析的结果与疾病模型对不同严重程度得分下生产的不同猪的比例的估计相结合，以评估农场水平的 PMWS 和亚临床疾病的成本，并将其推断至全国水平。H-S 猪的净利润为 19.2 英镑。PMWS-D 猪的平均损失为 84.1 英镑（90%CI：79.6-89.1），PMWS-R 猪为 24.5 英镑（90%CI：15.1-35.4），Sub-D 猪为 82.3 英镑（90%CI：78.1-87.5），Sub-S 猪为 8.1 英镑（90%CI：2.18-15.1）。在农场层面，最大的负面经济影响归因于 PCV2 亚临床猪。2008 年，在引入 PCV2 疫苗之前，英国养猪业的经济影响估计为每年 5260 万英镑（90%CI：3470-7200 万英镑），在流行期间每年约为 8800 万英镑。这是第一项使用经验数据在不同农场严重程度水平上对 PMWS/PCV2SI 成本进行建模的研究。该模型的结果将用于评估不同控制措施的效率，并为农民和决策者提供决策支持工具。
