Australian encephalitis (AE) is an arboviral (ie arthropod borne or in this case more specifically mosquito borne) disease caused predominantly by Murray Valley encephalitis virus, and occasionally by Kunjin virus. The disease was initially recognised as occurring in epidemics chiefly centred about the Murray-Darling system, but now is known to occur Australia-wide. The last major epidemic was in 1974; 58 people were affected, including five from the Northern Territory (NT).