Carpenter T E, Berry S L, Glenn J S
J Am Vet Med Assoc. 1987 Apr 15;190(8):983-7.
The epidemiology and economics of Brucella ovis control in a hypothetical, commercial sheep flock (100 rams and 2,500 ewes) were investigated. The investigation consisted of an epidemiologic simulation model, reported in a companion paper, and a decision-tree analysis, reported here. It was predicted from the simulation model that B ovis could be eradicated successfully in 2 test periods (less than 1 year) from a flock by using intensive screening and culling. A computerized decision-tree program was used to determine the economically optimal control strategy among several alternatives. Two versions of the program were used to determine the optimal alternative, based on minimizing the expected monetary loss (deterministic) and minimizing the associated risk (stochastic). The economically optimal alternative was to screen the rams by means of palpation, semen testing, and ELISA prior to the mating season. Rams positive to any test were culled. After the mating season was completed, the optimal action was to use ELISA for the remaining rams and to cull all that were ELISA positive. The cost of this alternative was approximately $6,150, or less than one half the annual cost of a vaccination program ($12,800) or no program ($13,550). Continuing palpation and semen testing were considered worthwhile on the basis of detecting new cases of B ovis infection and in maintaining high flock fertility. Similarly, the cost of annual use of ELISA was small (approximately $100), compared with the potential cost of not detecting a new case of B ovis infection.
对一个假设的商业羊群（100只公羊和2500只母羊）中绵羊种布鲁氏菌病的流行病学和经济学进行了调查。该调查包括一篇配套论文中报道的流行病学模拟模型和本文报道的决策树分析。从模拟模型预测，通过强化筛查和扑杀，在2个检测期（不到1年）内可成功根除羊群中的绵羊种布鲁氏菌。使用一个计算机化的决策树程序来确定几种替代方案中经济上最优的控制策略。该程序的两个版本用于确定最优替代方案，一个基于最小化预期货币损失（确定性），另一个基于最小化相关风险（随机性）。经济上最优的替代方案是在配种季节前通过触诊、精液检测和酶联免疫吸附测定（ELISA）对公羊进行筛查。任何检测呈阳性的公羊都予以扑杀。配种季节结束后，最优措施是对剩余的公羊使用ELISA检测，并扑杀所有ELISA检测呈阳性的公羊。该替代方案的成本约为6150美元，不到疫苗接种计划年度成本（12800美元）或无防控计划成本（13550美元）的一半。基于检测绵羊种布鲁氏菌感染新病例以及维持高羊群繁殖力，持续的触诊和精液检测被认为是值得的。同样，与未检测到绵羊种布鲁氏菌感染新病例的潜在成本相比，每年使用ELISA的成本较小（约100美元）。
