Ex-ante economic analysis of animal disease surveillance

Abstract

This paper provides an ex-ante economic analysis comparing four alternative intervention strategies for the control and eradication of rinderpest against a scenario of no intervention in a cattle population similar in size to that of Ethiopia. The interventions were three different coverage levels of mass vaccination and one surveillance-based programme where vaccination targeted infected sub-populations. For each scenario, the disease impact was estimated using an open-population, state-transition SEIR ('susceptible', 'exposed', 'infectious', 'recovered') disease transmission model with parameter estimates developed for lineage 1 rinderpest virus. Projected economic surplus gains and costs estimated from the rinderpest eradication programme in Ethiopia were analysed using benefit-cost methods. Social net present values (NPVs) and benefit-cost ratios (BCRs) were calculated. Although the economic model found that BCRs were greater than one for all interventions examined, the scenarios of intensive mass vaccination (75% vaccination coverage) and surveillance with targeted vaccination were economically preferable. The BCRs for these strategies were 5.08 and 3.68, respectively. Sensitivity analysis revealed that an increase in market prices for beef and milk increased the value of economic loss, the economic surplus and returns to investments in terms of NPVs and BCRs. An increase in demand and supply elasticities for beef and milk decreased the value of economic losses. This also had a negative effect on economic surplus and NPVs. The effect of an increase in the discount rate reduced returns to investments, with lower NPVs and BCRs. The authors note that 75% mass vaccination coverage was attempted in Ethiopia in the early 1990s, but failed to eradicate rinderpest because the approach was logistically too difficult to implement in practice. Subsequently, an effective surveillance and epidemiologically targeted vaccination programme was developed and has apparently resulted in the eradication of rinderpest from Ethiopia (the last case was recorded in 1996). The authors conclude that epidemio-surveillance with targeted vaccination is both an economically viable and realistic strategy and offers benefits that extend beyond rinderpest eradication.