Serological studies indicated that some non-fatal cases were due to KUN virus infection, although only MVE virus was associated with fatal cases. Since 1974, cases have occurred sporadically in northern Australia and in the northwest of WA in particular, but there have been no cases of MVE recorded in southeastern Australia. The proposal that the virus is endemic in northern Australia is supported by serological studies in Queensland and in northern Western Australia. Epidemic activity in the southeast has been associated with excessive rainfall which increases bird and mosquito populations and leads to a virus overflow infecting humans. Certainly, there is an association of previous outbreaks in the southeast with extraordinary rainfall and widespread flooding in the eastern Australian watersheds and the Murray-Darling basin in particular.
Cases vary from the mild to severe and fatal.
It is rare for recovery from the encephalitic syndrome to occur without some residual mental or functional disability. A variety of blood tests are used to demonstrate the presence of specific antibodies to MVE and KUN virus. Blood samples should be taken during the acute and convalescent phases of the illness, and a fourfold rise in antibody levels will confirm the clinical diagnosis. Prevention Prevention of mosquito borne viral diseases is mainly accomplished through reducing the threat of bites from mosquitoes. This can be achieved either through undertaking active mosquito control or by the use of personal protective measures.