Development of methodology to prioritise wildlife pathogens for surveillance

We developed and evaluated a methodology to prioritise pathogens for a wildlife disease surveillance strategy in New Zealand. The methodology, termed 'rapid risk analysis' was based on the import risk analysis framework recommended by the Office Internationale des Epizooties (OIE), and involved: hazard identification, risk estimation, and ranking of 48 exotic and 34 endemic wildlife pathogens. The risk assessment was more rapid than a full quantitative assessment through the use of a semi-quantitative approach to score pathogens for probability of entry to NZ (release assessment), likelihood of spread (exposure assessment) and consequences in free-living wildlife, captive wildlife, humans, livestock and companion animals. Risk was estimated by multiplying the scores for the probability of entry to New Zealand by the likelihood of spread by the consequences for free-living wildlife, humans and livestock. The rapid risk analysis methodology produced scores that were sufficiently differentiated between pathogens to be useful for ranking them on the basis of risk. Ranking pathogens on the basis of the risk estimate for each population sector provided an opportunity to identify the priorities within each sector alone thus avoiding value-laden comparisons between sectors. Ranking pathogens across all three population sectors by summing the risk estimate for each sector provided a comparison of total risk which may be useful for resource allocation decisions at national level. Ranking pathogens within each wildlife taxonomic group using the total risk estimate was most useful for developing specific surveillance strategies for each group.