Financial analysis of pseudorabies control and eradication in swine

Computerized decision-tree analysis and simulation modeling were used to evaluate control and eradication strategies for pseudorabies virus (PRV) in swine. Three alternative actions were considered for a hypothetical 100-sow, farrow-to-finish operation: (1) depopulation-repopulation, (2) test-and-removal of seropositives (T&R), and (3) vaccination (of the entire herd or of sows only). The expected monetary values for the vaccination and T&R alternatives were similar, which was consistent with the long-standing controversy over the best strategy for dealing with PRV. When the prevalence rate of PRV was less than or equal to 57%, T&R was found to be optimal; otherwise, vaccination of sows only was recommended. Sensitivity analysis was performed to determine how modifications in some of the original assumptions affected the expected monetary values of each strategy. When higher gross margins for the producer were assumed, T&R was preferred at all prevalence rates. Vaccination was preferred when lower gross margins, lower vaccination costs, or better protective effect of PRV vaccines on reproductive performance were assumed. The use of gene-deleted vaccines in conjunction with the T&R strategy was also evaluated. When this option was available, T&R was favored at any prevalence rate (T&R alone when the prevalence was less than or equal to 20%, or combined with gene-deleted vaccination at prevalences greater than 20%). Depopulation-repopulation was not the best option under any circumstance. Once formulated, a decision-tree analysis can be adapted to the prevailing economic or epidemiologic conditions; hence, it is a useful tool in the PRV decision-making process.