Innovative zoning to support equine influenza eradication from New South Wales, Australia.

Following detection of equine influenza (EI) in New South Wales, a complete standstill was imposed the next morning on the movement of all horses and donkeys within the state. Premises' biosecurity guidelines became progressively more stringent with time in an effort to stop local spread. The standstill was highly effective as a primary response to stop EI becoming widespread across Australia, but did not prevent spread to properties contiguous to infected premises in areas of high horse density and small property size, nor transmission by fomites nor possible local airborne transmission. Within 2 weeks of the start of the outbreak, a zoning system of Purple (Special Restricted), Red (Restricted), Amber (Control), and Green (Protected) Zones was implemented, and progressively modified as disease distribution changed. The colour coding system proved to be an easy way to communicate zone changes, the approximate level of disease risk and the stringency of movement restrictions to the general public and should be adopted more generally in AUSVETPLAN.