Exploring the potential for Ross River virus emergence in New Zealand.

Ross River virus (RRV) is an exotic vector-borne disease considered highly likely to emerge as a future human health issue in New Zealand, with its range expansion from Australia being driven by exotic mosquito introduction and improving conditions for mosquito breeding. We investigated our ability to assess the potential for such emergence using deterministic modeling and making preliminary predictions based on currently available evidence. Although data on actual mosquito densities (as opposed to indices) were identified as a need for predictions to be made with greater confidence, this approach generated a contrasting prediction to current opinion. Only limited potential for RRV emergence in New Zealand was predicted, with outbreaks in the human population more likely of concern in urban areas (mainly should major exotic vectors of the virus establish). The mechanistic nature of the model also allowed the understanding that if such outbreaks do occur, they will most likely be driven by virus amplification in dense human populations (as opposed to the spillover infection from wildlife common in Australia). With implications for biosecurity and health care resource allocation, modeling approaches such as that employed here have much to offer both for disease emergence prediction and surveillance strategy design.