Transcript 3 Australia`s prawn disease status

Australia’s Disease
Status and Risk
Pathways
Dr Matt Landos1 BVSc(HonsI)MANZCVS
Dr Christine Huynh BVSc
Future Fisheries Veterinary Service Pty Ltd
Prawn Superpowers Summit
31 July 2012, QLD
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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 statusproduction impact
2011: World production fell ~20% to 2.5 million tonnes with disease and
unfavorable weather
Thailand: production forecast to increase to 700 000 t in 2012
India: production of black tiger may decline 40–50 percent to 60 000–70 000 t.
Vannamei producers, could increase 30% to 100,000 tonnes in 2012.
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
S Gill-associated virus (GAV)
S Monodon Baculovirus (MBV)- [Spherical baculovirus]
S Hepatopancreatic parvovirus (HPV) =PmergDNV densovirus
S Spawner isolated mortality virus (SMV)
S Mourilyan Virus (MOV)
S White tail disease – Macrobrachium rosenbergi nodavirus
(MrNV)
Prawn Superpowers Summit
31 July 2012, QLD
Diseases not detected in the
‘lucky country’ - Australia
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White Spot Disease (WSSV)
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Yellowhead (YHV)
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Taura Syndrome (TSV)
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Infectious myonecrosis virus (IMNV)
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Early mortality syndrome (EMS)
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Loose shell syndrome
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Abdominal Segment Deformity Syndrome
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Monodon slow growth syndrome (MSGS)
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GOOD MANAGEMENT
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AQIS IRA- import testing green prawns
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Remote location of farms to Asia
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No live prawn imports
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Vertical farm integration- limited PL &
equipment sharing
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High quality feed, pond management
Prawn Superpowers Summit
31 July 2012, QLD
Gill- Associated Virus
S Visual signs:
S Biofouling with ectoparasites, reddening of tail fan
S Birds feeding on sick shrimp, shrimp coming to edge of the
pond, decreased feed intake
S Shortened antennae
Prawn Superpowers Summit
31 July 2012, QLD
Gill-Associated Virus (GAV)=
Mid Crop Mortality Syndrome
S Outbreaks with higher viral
load post stocking + stress=
mortalities
S High viral load at 4 weeks
post stock = 95% chance of
disease outbreak,…. Cull
recommended
S Chronic low grade losses in
lesser affected ponds
S Asymptomatic carriers common
from all east coast wild caught
spawners
S Gulf stock low risk- appear to be
free from GAV at this time
S Transmission: horizontal-water,
ingestion; Vertical transmission
also possible from broodstock to
larvae
Prawn Superpowers Summit
31 July 2012, QLD
Monodon Baculovirus (MBV)
S Clinical signs:
S Emaciation- go dark in colour, not feeding, lethargic, gill shell
fouling
S Pale hepatopancreas
S Transmission: horizontal- via water or cannibalism
S Washing nauplii in disinfected water can manage infecti
S Impression smear techniques available for rapid diagnosis
Prawn Superpowers Summit
31 July 2012, QLD
Hepatopancreatic parvovirus
S Australian strain named Penaeus merguiensis
densovirus (La Fauce, Elliman & Owens
2007)
S Associated with stunting, and occasional
mortality outbreak in P. Merguiensis
S Damages gut lining of shrimp
S Desirable to stock low viral load prawns
Prawn Superpowers Summit
31 July 2012, QLD
Spawner Isolated Mortality
virus
S Northern Australian prawns affected in the mid- 1990s,
affecting P.monodon and P.merguiensis
S Reported in Eastern Australian prawns (particularly QLD),
currently considered exotic to NSW.
S Associated with monodon broodstock mortality
S Associated with mid-crop mortality syndrome
S Associated with reduced larval survival from positive
broodstock
Prawn Superpowers Summit
31 July 2012, QLD
Mourilyan Virus- appears non
pathogenic
S Mourilyan virus has been isolated in P.Monodon populations
S Horizontal transmission reported
S Observed in muscle, gill, HP, lymphoid and haematopoietic
and neural tissue
S Diagnosed by EM, PCR and Histopathology
S Uncertain if it is pathogenic to monodon at all
S 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)
S Abdomen is milky and opaque-
discolouration starts at the tail and eventually
spreads throughout the body
S High mortality rates of >95%
S Outbreaks will normally occur in juveniles,
PLs, and larvae
S Present in inland Qld- risks to marine prawns
Prawn Superpowers Summit
31 July 2012, QLD
Risk Pathways
S Importation of live stock- broodstock /untested PL’s
S Source water/ ballast shipping increase/ ports expansion
S Imported frozen uncooked product/ rec fishing bait/ processors
S Importation of unpasteurised feed/ equipment
S People movement
S Entry of carrier crustaceans- eg soft shell frozen crab
Prawn Superpowers Summit
31 July 2012, QLD
Border Biosecurity Model
• Exporting countries testing and reporting
• Competent authority- are they competent to certify freedom?
• Import risk assessment
• Border security- AQIS- Quarantine and testing
• Surveillance/ reporting of disease on-farm
• Diagnostic laboratory confirmation
• State/National Emergency response protocols
Reportable Diseases in
Australia
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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