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Authorities hunt for source of prawn virus

AAP logoAAP 14/12/2016 Tracey Ferrier

Authorities are carrying out exhaustive investigations in a bid to determine how a prawn virus that's common overseas arrived in Australia.

Biosecurity Queensland has confirmed white spot disease is present on a fourth farm near the Logan River, south of Brisbane, but says that's no surprise.

Growing ponds for all four affected farms are extremely close together. Four other farms in the same general area, but some kilometres away, have returned negative results.

"Results are coming in daily with positive results recorded in the ponds at the group of four aquaculture premises south of the Logan River where the virus was first confirmed," Queensland's chief biosecurity officer, Jim Thompson, said on Wednesday.

Tests are also continuing in the Logan River, where infected wild prawns have also been found.

"At this stage, it is not known how the virus came to be present on the aquaculture premises or in wild prawns in the Logan River," Dr Thompson said.

"Biosecurity Queensland is conducting tracing investigations of materials on and off the affected premises to try and determine the origin of the virus and its potential geographical spread."

All eight properties in the outbreak area are subject to movement restrictions, as work to destroy prawn stocks on the four positive farms continues.

"Destocking is almost complete on three premises, and about to commence on a fourth," Dr Thompson said.

Tests on remaining stock at a hatchery that supplied the infected farms have not shown any trace of the disease, but testing is continuing.

Dr Thompson said there was no indication so far about whether one of the prawn farms, or the river, was the source of the original infection.

Asked if eradication was still the objective, he admitted he didn't yet know if the virus was "established" in the river.

"Further testing is being undertaken to determine the extent of this infection," he said.

Until this month, Australia had been considered free of white spot, which has had devastating effects on farmed prawn production in infection zones overseas.

The virus poses no risk to humans, but can have a high mortality rate in the host species it infects.

Major retailers Coles and Woolworths have said the disease outbreak won't affect prawn supplies this Christmas.

"No Prawns from farms in South East Queensland impacted by the white spot disease were sent to stores for Christmas sale," Woolworths said.

Coles said it didn't source prawns from any farm affected by the white spot outbreak.

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