Demonstrating freedom from equine influenza in New South Wales, Australia, following the 2007 outbreak

To quantify the probability of freedom from equine influenza (EI) in New South Wales (NSW), Australia, based on analysis of polymerase chain reaction (PCR) testing.

Testing in the infected areas of NSW during the period 1 January to 30 April 2008.

Data from the random survey were collated and analysed to provide estimates of the probability of detecting EI if it was present at a prevalence ranging from 0.01% to 0.5%. The sensitivity estimates were then combined with a prior estimate of the probability of freedom in a simulation model, to estimate the posterior probability of freedom from EI (given the negative results of the random survey).

The very large volume of PCR tests performed provided a very high level of confidence that EI had been successfully eradicated from NSW.