Reichel Michael P, Ellis John T
Gribbles Veterinary Pathology, P.O. Box 536, Palmerston North, New Zealand.
Vet Parasitol. 2006 Nov 30;142(1-2):23-34. doi: 10.1016/j.vetpar.2006.06.027. Epub 2006 Aug 7.
Recent work on Neospora caninum, a protozoan parasite that causes abortions in dairy cattle has focused on a number of different control options. Modelling has suggested the most effective options for control but the present paper argues that the most effective option might not necessarily be optimal from an economic point of view. Decision trees, using published quantitative data, were constructed to choose between four different control strategies. The costs of these interventions, such as 'test and cull', therapeutic treatment with a pharmaceutical, vaccination or "doing nothing" were compared, and modelled, in the first instance, on the New Zealand and Australian dairy situation. It is argued however, that the relative costs in other countries might be similar and that only the availability of a registered vaccine will change the decision tree outcomes, as does the within-herd prevalence of N. caninum infection. To "do nothing" emerged as the optimal economic choice for N. caninum infections/abortions up to a within-herd prevalence of 18%, when viewed over a 1-year horizon, or 21% when costs were calculated over a 5 years horizon. For a higher (>or=21%) within-herd prevalence of N. caninum infection vaccination provided the best (i.e. most economic) strategy. Despite being the most efficacious solutions, 'test and cull' or therapeutic treatment never provided a viable economic alternative to vaccination or "doing nothing". Decision tree analysis thus provided clear outcomes in terms of economically optimal strategies. The same approach is likely to be applicable to other countries and the beef industry, with only minor changes expected in the relationships of decisions versus within-herd prevalence of N. caninum infection.
犬新孢子虫是一种可导致奶牛流产的原生动物寄生虫，近期针对它的研究聚焦于多种不同的控制方法。模型分析已提出了最有效的控制方法，但本文认为，从经济角度来看，最有效的方法未必是最优的。利用已发表的定量数据构建决策树，以在四种不同的控制策略之间进行选择。对这些干预措施的成本进行了比较和建模，这些干预措施包括“检测并淘汰”、药物治疗、疫苗接种或“不采取任何措施”，首先以新西兰和澳大利亚的奶牛养殖情况为模型。然而，有人认为其他国家的相对成本可能相似，只有已注册疫苗的可用性会改变决策树的结果，犬新孢子虫感染在牛群中的流行率也会产生同样的影响。从1年的时间跨度来看，对于牛群中犬新孢子虫感染/流产率高达18%的情况，“不采取任何措施”是最优的经济选择；从5年的成本计算期来看，这一比例为21%。对于牛群中犬新孢子虫感染率更高（≥21%）的情况，疫苗接种提供了最佳（即最经济）策略。尽管“检测并淘汰”或治疗是最有效的解决方案，但它们从未提供过比疫苗接种或“不采取任何措施”更可行的经济选择。因此，决策树分析在经济最优策略方面提供了明确的结果。同样的方法可能适用于其他国家和牛肉行业，预计在决策与牛群中犬新孢子虫感染流行率的关系方面只会有微小变化。
