White spot disease

White spot disease is a highly contagious viral disease of decapod crustaceans. These include prawns, crabs, yabbies and lobsters.

White spot syndrome virus (WSSV) causes the disease.

White spot disease does not pose a threat to human health or food safety.

Detection in Australia

White spot disease was detected in black tiger prawns (Penaeus monodon) on 3 prawn farms on the NSW north coast in early 2023.

The NSW Department of Primary Industries (NSW DPI) led the emergency response to this outbreak. The affected prawn farms have been decontaminated and disinfected. The response has been finalised and has now transitioned to a management phase.

NSW movement restrictions

Movement of decapod crustaceans or polychaete worms from the Clarence River control zone is currently restricted under NSW’s biosecurity control order. The control order is in place until 8 June 2025. While there are some exemptions, most decapod crustaceans are considered high-risk and can’t be moved out of the control zone. High-risk decapod crustaceans include, but are not limited to, raw prawns, yabbies and pink nippers.

NSW DPI is working with prawn farmers, fishers and the bait industry to manage the impact of this order.

See NSW restrictions and map of Clarence River control zone

Testing and surveillance

Wild prawns and crustaceans in the Clarence River control zone, including adjacent offshore areas, have been tested for WSSV.

Initial surveillance conducted within the Clarence River control zone in February 2023 found trace levels of WSSV DNA in a small number of samples.

Surveillance and tracing will continue at prawn the farms in the Clarence River, as well as the coastal and offshore areas. This includes further testing of wild crustaceans. The results of the NSW WSSV surveillance program will be used to inform future management decisions.

CSIRO’s Australian Centre for Disease Preparedness (ACDP) confirmed the WSSV strains that were detected at the NSW farms in early 2023 were strongly similar to the WSSV detected in NSW in August 2022, and, of different lineage to the Queensland WSSV strain detected in 2016-2020.

Investigations have not been able to determine the origin of the infection in NSW in 2022 or 2023.

Previous detections

In 2016, white spot disease was detected in 7 prawn farms on the Logan River in Southeast Queensland. In 2017 it was found in wild populations of crustaceans in the northern part of Moreton Bay, Southeast Queensland.

Prawns on the infected farms were destroyed and 5 farms resumed production in late 2018.

In August 2022, WSSV was detected at a biosecure prawn hatchery in northern NSW. It was contained and eradicated from the facility. Extensive investigations were unable to determine the origin of the outbreak.

See more

How we coordinate a response to an outbreak

Your obligations

What you must do to stop the spread of white spot disease.

Report sightings

Report anything unusual, even if you’re not sure.

If you suspect disease on your farm, call the Emergency Animal Disease Hotline on 1800 675 888. You’ll be directed to your state or territory government.

Follow the rules

White spot disease spreads between waterways through contaminated bait and fishing equipment. 

You can help prevent the spread of white spot disease. Make sure you’re aware of restrictions in place or actions you can take to reduce risks.

Queensland restrictions

Queensland has a movement regulated area (MRA) in place. WSSV has established in some populations of wild crustaceans within the MRA. The MRA extends from Caloundra to the NSW border and west Ipswich. 

You cannot move high-risk aquatic animals out of this area. This includes uncooked prawns, yabbies and marine worms. 

You also need to be aware of fishing restrictions in this area.

A national surveillance program that commenced in 2017 demonstrated that all areas of Australia, outside of the MRA, were free from the virus until the detection in NSW in 2022. 

See more on restrictions in Queensland

Other states and territories

Check for entry restrictions into other states and territories.

• Western Australia
• South Australia

Prawn and seafood farmers

Make sure that appropriate biosecurity measures are in place on your farm. This includes sourcing disease-free stock and animal feed.

All livestock, water and people coming in and out of your farm must be clean. Clean and disinfect all equipment and footwear.

Recreational and commercial fishers

Steps to keep your favourite fishing spot disease free:

• Do not use seafood meant for human consumption as bait.
• Use local and reputable bait shops or source your own bait from local waterways.
• Put all unwanted seafood in a rubbish bin, not in the ocean or waterways.
• Keep your fishing gear, boat and trailer clean. Make sure that you remove bait, debris and seaweed. Check, clean and dry wheel arches on trailers, boat propellers, fishing tackle and footwear.
• Use soapy water to clean your boat and trailer, fishing rods and other equipment. Allow them to dry completely before using them at another location, even if it is on the same day.

Import conditions for prawns

The Australian Government Department of Agriculture, Fisheries and Forestry (DAFF) conducted a review of prawn import conditions. This was the ‘Review of the biosecurity risks of prawns imported from all countries for human consumption’. 

DAFF released the final report of the prawn review on 5 June 2023.

The final report determined that:

• prawns and prawn products can be safely imported into Australia under the enhanced import conditions implemented since 2017
• additional strengthened import conditions were recommended for uncooked and cooked prawns.

DAFF started to implement changes to the import conditions for prawns and prawn products for human consumption from 30 October 2023.

See more on the review of prawns and prawn products.

Measures to ensure Australia’s import conditions are being met include pre and post border disease testing, retail testing, and working with exporting countries.

DAFF will continue to:

• monitor and enforce import conditions
• work with Australia’s trading partners and importers
• manage market access
• respond to systemic or non-compliance issues with appropriate enforcement actions.

About the disease

White spot disease is widespread in prawn farming regions in Asia and the Americas. The disease has caused severe losses on prawn farms in these regions.

What to look for

Prawns with white spot disease may have a loose shell with many white spots on the inside surface. The spots have a pink to red discolouration and are 0.5-2.0 mm in diameter.

More reliable signs to look for include:

• unusual mortality
• prawns coming to the edge or water surface of the pond
• prawns demonstrating unusual swimming patterns or lethargy
• reduced feeding and failure to thrive.

Animals infected with the virus may show one or more of these distinctive signs. Or they may not show these signs at all, and the virus may still be present.

White spot disease can be confused with spots of crystallised salt under the shell. Prawns absorb salt as they are frozen in a saline solution. This can crystallise under the shell which causes white mottling to appear. This mottling can be found on the body and head and becomes more noticeable as the prawns defrost.

You can use the aquatic animals identification guide (agriculture.gov.au)

If you’re not sure, you can get advice from the Emergency Animal Disease Hotline on 1800 675 888.

How it spreads

The disease is spread by:

• infected aquatic animals, including prawns, freshwater crayfish, crabs and polychaete worms
• contaminated equipment or water
• birds that feed on and move infected animals.

Effect on other species

Finfish are not affected by the disease and are not a carrier of the disease.

White spot in aquarium fish is a parasitic skin infection. It is not related to white spot disease of crustaceans.