The NSW arbovirus surveillance program for monitoring mosquito populations has been conducted annually since the summer of 1984/85, with arbovirus isolations from the mosquitoes beginning in the 1988/89 season. There have been two collection sites each at up to 30 locations throughout the state, in coastal and inland regions. The trapping program is designed to cover the period of seasonal increase and decrease in the populations of the major arbovirus vectors, from mid-spring to mid-autumn, and also to cover the period for natural activity and transmission of arboviruses (especially the alphaviruses and the flaviviruses).

The compilation and analysis of data collected over a number of successive years will provide a solid base from which to determine the underlying causes for the seasonal fluctuations in arbovirus activity and the relative abundance of the mosquito vector species affecting the well-being of human communities. This information will be the basis for modifying existing local and regional vector control programs, and the creation of new ones.

To monitor mosquito vector populations in coastal and inland areas of N.S.W. at risk of arbovirus activity by routine sampling; identify the major pest and vector species for each locality, and monitor population fluctuations of the important species (especially Culex annulirostris for inland areas and Aedes vigilax for coastal sites).

   To identify arbovirus (both flavivirus and alphavirus) activity by processing mosquito samples, isolating arboviruses through cell culture and identifying isolated arboviruses with serological techniques.

To analyse environmental data relevant to vector mosquito and arbovirus activity.

To provide early warning of activity of arboviruses and vector mosquitoes of concern for the public health of N.S.W.

   To provide increasing understanding of interrelationships between arboviruses, vectors and environmental conditions in the various regions of N.S.W.

Public Health Units (PHU) and Local Government Councils will have early warning of the need to undertake vector control measures and issue media releases warning the public to take self-protective actions.

PHUs and Councils will have accurate information required to maximise the effect of any control measures.

  The Health Department will have reliable data to assess the need to implement the Contingency Plan for the Control of Arbovirus Disease in N.S.W., notably in relation to the flaviviruses Murray Valley Encephalitis and Kunjin.

The Program has recorded 59 different mosquitoes, including several new to New South Wales, and has extended the known distribution of many important species.

Continual trapping over many years has provided baseline data for mosquito population abundance at several locations throughout NSW. This allows for the interpretation of fluctuations in population numbers and provides a possible alert to arbovirus activity.

   The Program has identified the following arboviruses in New South Wales: the alphaviruses, Ross River, Barmah Forest and Sindbis; the flaviviruses, Kunjin, Edge Hill, Stratford and Kokobera; and the bunyaviruses, Gan Gan and Trubanaman. Many localities have new records for these viruses.

   The Program has identified the presence of unusual virus activity and alerted health authorities, prior to the recognition of human infection. This occurred in 1990/91 when Kunjin was identified from the inland areas, and 1994/95 when Barmah Forest virus was identified from the south coast of NSW.