A qualitative approach to measure the effectiveness of active avian influenza virus surveillance with respect to its cost: a case study from Switzerland.

The aim of the project was to apply cost-effectiveness analysis to the economic appraisal of avian influenza virus (AIV) surveillance, using the implemented surveillance programme in Switzerland as a case study. First a qualitative risk assessment approach was used to assess the expected impact of surveillance on the transmission and spread of AIV. The effectiveness of surveillance was expressed as the difference in defined probabilities between a scenario with surveillance and a scenario without surveillance. The following probabilities were modelled (i) transmission of highly pathogenic AIV (HPAIV) from wild birds to poultry, (ii) mutation from low pathogenic AIV (LPAIV) into HPAIV in poultry, and (iii) transmission of HPAIV to other poultry holdings given a primary outbreak. The cost-effectiveness ratio was defined conventionally as the difference in surveillance costs (ΔC) divided by the change in probability (ΔP), the technical objective, on the presumption that surveillance diminishes the respective probabilities. However, results indicated that surveillance in both wild birds and poultry was not expected to change the probabilities of primary and secondary AIV outbreaks in Switzerland. The overall surveillance costs incurred were estimated at 31,000 €/year, which, to be a rational investment of resources, must still reflect the value policy makers attribute to other benefits from having surveillance (e.g. peace of mind). The advantage of the approach adopted is that it is practical, transparent, and thus able to clarify for policy makers the key variables to be taken into account when evaluating the economic efficiency of resources invested in surveillance, prevention and intervention to exclude AIV.