Imported cases of Ross River virus disease in New Zealand - a travel medicine perspective.

No known locally acquired human mosquito-borne diseases have occurred in New Zealand, and reported cases of arboviral infections have been diagnosed exclusively in travellers. In this paper, we review the epidemiology of Ross River virus cases (RRV) in New Zealand and discuss the potential risk of local disease transmission. Cases of RRV reported to the Notifiable Disease Surveillance system from 1997 to 2009 were analysed. Available data included demographics, travel history and mosquito avoidance behaviour. A total of 22 cases of RRV were reported, and included New Zealand residents returning home from overseas (20 cases, 14 to Australia, 5 to Fiji, 1 unknown destination) as well as international visitors (2 from Australia). Reported cases of RRV confirm that New Zealand is vulnerable to virus importation. With several potential mosquito vectors, it is theoretically possible for a local "virgin soil" epidemic to occur. It is important for travellers, medical practitioners, and public health authorities to be aware of this threat, and take appropriate precautions to reduce the risk of a local epidemic. Protecting travellers from RRV is important from a travel medicine perspective, but also has potentially significant public health benefits for the general population.