 Australia’s Disease Status and Risk Pathways Dr Matt Landos 1 BVSc(HonsI)MANZCVS Dr Christine Huynh BVSc Future Fisheries Veterinary Service Pty Ltd Prawn Superpowers Summit 31 July 2012, QLD

Australian prawn production Farmed Industry value 1996: $35 million 2007: $45 million (monodon(65%) and merguiensis(35%)). 2012: $80 million Wild harvest industry ~ 20,000t Limited new farm sites due to social factors and environmental policy. Potential for existing farms to increase production through further intensification of production. With intensification comes increased disease risk. Control of GAV on some farms has been associated with improved production per hectare Prawn Superpowers Summit 31 July 2012, QLD

World disease status- production impact 2011 : World production fell ~20% to 2.5 million tonnes with disease and unfavorable weather Thailand: production forecast to increase to t in 2012 India: production of black tiger may decline 40–50 percent to – t. Vannamei producers, could increase 30% to 100,000 tonnes in Malaysia: vannaemi production down 43% in 2011 Vietnam: Supplies of vannamei are also expected to increase Diseases including EMS, WSSV and IMNV are major threats to production targets and remain the source of substantial losses to the industry outside of Australia

World diseases causing losses China: WSSV and Early Mortality Syndrome (EMS) or Acute Hepatopancreatic necrosis syndrome (AHPNS). 2011: 80% loss from Guangdong, Hainan, Guangxi, and Fujian Thailand: EMS, flooding, WSSV decreased production Vietnam: Increased WSSV, EMS ($70 million loss in 2011), Vibriosis and IMNV, antibiotic residue, environmental and salination problems Indonesia: Ongoing problems with IMNV Malaysia: WSSV problems in 2011 and in cooler weather, EMS

Diseases detected in Australia  Gill-associated virus (GAV)  Monodon Baculovirus (MBV)- [Spherical baculovirus]  Hepatopancreatic parvovirus (HPV) =PmergDNV densovirus  Spawner isolated mortality virus (SMV)  Mourilyan Virus (MOV)  White tail disease – Macrobrachium rosenbergi nodavirus (MrNV) Prawn Superpowers Summit 31 July 2012, QLD

Diseases not detected in the ‘lucky country’ - Australia  White Spot Disease (WSSV)  Yellowhead (YHV)  Taura Syndrome (TSV)  Infectious myonecrosis virus (IMNV)  Early mortality syndrome (EMS)  Loose shell syndrome  Abdominal Segment Deformity Syndrome  Monodon slow growth syndrome (MSGS) Prawn Superpowers Summit 31 July 2012, QLD  GOOD MANAGEMENT  AQIS IRA- import testing green prawns  Remote location of farms to Asia  No live prawn imports  Vertical farm integration- limited PL & equipment sharing  High quality feed, pond management

Gill- Associated Virus  Visual signs:  Biofouling with ectoparasites, reddening of tail fan  Birds feeding on sick shrimp, shrimp coming to edge of the pond, decreased feed intake  Shortened antennae Prawn Superpowers Summit 31 July 2012, QLD

Gill-Associated Virus (GAV)= Mid Crop Mortality Syndrome  Outbreaks with higher viral load post stocking + stress= mortalities  High viral load at 4 weeks post stock = 95% chance of disease outbreak,…. Cull recommended  Chronic low grade losses in lesser affected ponds Prawn Superpowers Summit 31 July 2012, QLD  Asymptomatic carriers common from all east coast wild caught spawners  Gulf stock low risk- appear to be free from GAV at this time  Transmission: horizontal-water, ingestion; Vertical transmission also possible from broodstock to larvae

Monodon Baculovirus (MBV)  Clinical signs:  Emaciation- go dark in colour, not feeding, lethargic, gill shell fouling  Pale hepatopancreas  Transmission: horizontal- via water or cannibalism  Washing nauplii in disinfected water can manage infecti  Impression smear techniques available for rapid diagnosis Prawn Superpowers Summit 31 July 2012, QLD

Hepatopancreatic parvovirus  Australian strain named Penaeus merguiensis densovirus (La Fauce, Elliman & Owens 2007)  Associated with stunting, and occasional mortality outbreak in P. Merguiensis  Damages gut lining of shrimp  Desirable to stock low viral load prawns Prawn Superpowers Summit 31 July 2012, QLD

Spawner Isolated Mortality virus  Northern Australian prawns affected in the mid- 1990s, affecting P.monodon and P.merguiensis  Reported in Eastern Australian prawns (particularly QLD), currently considered exotic to NSW.  Associated with monodon broodstock mortality  Associated with mid-crop mortality syndrome  Associated with reduced larval survival from positive broodstock Prawn Superpowers Summit 31 July 2012, QLD

Mourilyan Virus- appears non pathogenic  Mourilyan virus has been isolated in P.Monodon populations  Horizontal transmission reported  Observed in muscle, gill, HP, lymphoid and haematopoietic and neural tissue  Diagnosed by EM, PCR and Histopathology  Uncertain if it is pathogenic to monodon at all  In co-infections with GAV, it is GAV that appears to be the cause of mortality, not MoV Prawn Superpowers Summit 31 July 2012, QLD

White tail disease (Macrobrachium rosenbergii Nodavirus)  Abdomen is milky and opaque- discolouration starts at the tail and eventually spreads throughout the body  High mortality rates of >95%  Outbreaks will normally occur in juveniles, PLs, and larvae  Present in inland Qld- risks to marine prawns Prawn Superpowers Summit 31 July 2012, QLD

Risk Pathways  Importation of live stock- broodstock /untested PL’s  Source water/ ballast shipping increase/ ports expansion  Imported frozen uncooked product/ rec fishing bait/ processors  Importation of unpasteurised feed/ equipment  People movement  Entry of carrier crustaceans- eg soft shell frozen crab Prawn Superpowers Summit 31 July 2012, QLD

Border Biosecurity Model Pre-Border Exporting countries testing and reporting Competent authority- are they competent to certify freedom? Import risk assessment Border Border security- AQIS- Quarantine and testing Post-Border Surveillance/ reporting of disease on-farm Diagnostic laboratory confirmation State/National Emergency response protocols

Reportable Diseases in Australia  Taura Syndrome  White Spot Disease  Yellowhead disease- Yellowhead virus  Gill-associated virus  Infectious Hypodermal and Haematopoietic Necrosis  Crayfish Plague ( Aphanomyces Astaci )  White tail disease  Infectious Myonecrosis  Monodon Slow Growth Syndrome  Milk haemolymph disease of spiny lobster  Necrotising hepatopancreatitis