Treatment to eradicate white spot disease has finished at five prawn farms in southeast Queensland where the infection was detected late last year.

White spot disease remains a threat to prawns in Queensland despite the state's unprecedented and swift attempt to eradicate the infection.

Biosecurity Queensland announced on Thursday that it had finished treating five aquaculture farms on the Logan River, south of Brisbane, where the disease was detected in late 2016.

"While we've made good progress, there is still a long way to go before we can confirm that white spot disease is no longer a threat," chief biosecurity officer Jim Thompson said.

White spot disease is a highly contagious viral infection that is deadly to prawns but not harmful to humans.

Farmers strongly suspect the virus hitched a ride to Australia with deliveries imported from infection zones overseas, but the source of the outbreak is yet to be proven.

Dr Thompson said 112 production ponds at the five infected premises had been treated with 2.8 million litres of chlorine - the largest aquatic animal disease response ever seen in Queensland.

"I am particularly grateful for the actions of these farmers during the early stages of the response who bore the costs of keeping pond aeration and circulation equipment operating while chlorine treatment commenced," he said.

A financial assistance package is now being developed to compensate farmers and help accelerate the process of eliminating the disease.

Earlier this month the federal government revealed it was pursuing criminal charges against at least one importer alleged to have deliberately flouted testing regimes designed to keep Australia white spot-free.

Four other importers are also under investigation.

Authorities are expected to allege that at least one importer hand-picked only healthy prawns for independent testing, from deliveries otherwise known to have white spot.