Ecological studies of vectors of bluetongue and other important arboviruses in Southern Australia

Summary

During this project, knowledge of the ecology of C. brevitarsis in coastal NSW has been greatly expanded. Factors limiting the distribution and abundance of the midge have been identified. Models have been developed which predict the survival of C.brevitarsis during winter, its first occurrence and distribution. It is now also possible to determine the length of time that this vector will survive in a location and the probability for it to survive through the winter.

The data that is now available for use in these new vector forecasting systems will allow refinement of insect monitoring in the future. As an outcome of the development of new ELISA tests for the detection of antibodies to Akabane and the other Simbu viruses, sensitive low cost tools are available for determining the distribution of infection of livestock with these important viruses. With a combination of the vector models and low cost ELISA tests, virus and vector free areas can be more readily and efficiently defined. The accurate description of these free areas should facilitate livestock exports.

Further, changes in vector and virus distribution may be predicted and populations of livestock at risk of arbovirus induced disease identified, allowing the implementation of control measures. However, care should be taken during the promotion of virus and vector free areas not to compromise the status of this area by making any remarks about Bovine Ephemeral Fever virus. With a probable mosquito vector, Bovine Ephemeral Fever virus is occasionally found well beyond the limits of the C. brevitarsis endemic area, in the "vector-free" area and should always be considered in a separate category to the Culicoides-borne viruses.