Bluetongue viruses, vectors and surveillance in Australia - the current situation and unique features.

While there are dramatic differences between recent bluetongue (BT) developments in Europe and the situation in Australia, there are also a number of similarities. About 25 years ago, as a BT-free country, Australia was advised that a BT virus (BTV) had been identified, though there was no evidence of disease. During the following 15 years, 8 BTV serotypes were identified. Despite the presence of some virulent viruses, Australia remains free of BT disease. Nevertheless, the economic impact is considerable due to disruption to trade. In the last decade, research efforts have focussed on reducing the impact of BTVs on the export of livestock, semen and embryos. In 1993, the National Arbovirus Monitoring Program (NAMP) was established as a co-operative initiative between the livestock industries, national and state governments. The main emphasis of NAMP has been to define the distribution of BTVs and their vectors, together with monitoring annual fluctuations of viruses and vectors. A combination of climatic, geographical, virus and vector monitoring data that have been gathered over more than 25 years, have allowed the accurate delineation of BTV-free zones and zones of possible BTV transmission in accordance with OIE guidelines. These zones are now promoted to trading partners to facilitate trade.