There have been nine different arboviruses isolated from mosquitoes collected in the Top End of the NT that are either known or suspected of causing disease in humans. These include: the alphaviruses Ross River virus (RRV) and Barmah Forest virus (BFV), which are the most frequently confirmed causes of arbovirus disease in Australia: and the flaviviruses Murray Valley encephalitis virus (MVE) and Kunjin virus (KUN) which can cause serious illness and have been responsible for periodic outbreaks and isolated cases of disease in the Northern Territory.