Susceptibility of previously untested fish species to EHN Virus, and the epidemiology of EHN Virus in the Murray Darling Basin

Epizootic Haematopoietic Necrosis Virus(EHNV) is considered to be a serious threat to a number of native fish species in the Murray Darling Basin. This virus, unique to Australia, was first isolated in 1985 in redfin perch. It causes sudden mortalities and the fish display necrosis of the renal haematopoietic tissue, liver, spleen and pancreas. Experimental work by Langdon [1] demonstrated that a number of native species were susceptible to the disease, including the threatened Macquarie perch and silver perch, as well as mountain galaxias. The virus has been recorded from Victoria, New South Wales, South Australia and the ACT. The spread of EHNV has been aided by its relative resistance. It can be readily transmitted from one location to another in water, by infected fish, and likely also on nets, fishing lines, boats and other equipment [2, 3]. Langdon found that the virus retained its infectivity after being stored dry for 113 days. Once EHNV has entered a water body it is considered impossible to eradicate.