Early mortality syndrome EMS Acute hepatopancreatic necrosis disease AHPND Dr Matt Landos Director Future Fisheries Veterinary Service Pty Ltd Kelly Condon James Cook University Potted International history AHPND ID: 617612
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Penaeus monodon mortality syndrome (PMMS)Early mortality syndrome (EMS)Acute hepatopancreatic necrosis disease (AHPND)
Dr Matt Landos Director, Future Fisheries Veterinary Service Pty LtdKelly Condon James Cook UniversitySlide2Slide3
Potted International history AHPNDEmerged from China in ~ 2009-10 of new diseaseVague reports of spread through Thailand, Vietnam, Americas
Huge farm losses up to day 30 initially (now out to day 110)FAO convened workshop 2013 on EMSPathology caused by PirAB toxin production from a Vibrio in stomachOIE definition initially confined to Vibrio parahaemolyticus, soon to be broadened to include other Vibrio’s and plasmidNow reported in Vibrio harveyi also in Asia and AustraliaIn Asia PirAB toxin associated with a plasmid (
ie
independent of bacterial DNA)
In Australia,
PirAB
not associated with a plasmid, it is part of chromosomeSlide4
Clinical signs of AHPNDHepatopancreas (HP) often pale to white due to pigment loss in the connective tissue capsuleSignificant atrophy (shrinkage) of HPOften soft shells and guts with discontinuous contents or no content
Black spots or streaks sometimes visible within the HPHP does not squash easily between thumb and fingerOnset of clinical signs and mortality starting as early as 10 days post-stockingMoribund shrimp sink to the bottomSlide5
PMMS Outbreaks 2015-2016Slide6
PMMS screening 201613 farms from Northern NSW to Far north Qld980 samplesAll P monodon sampled for PCR and tissue stored for histologyTargeted prawns with signs of poor health
10 prawns per pondPond numbers varied relative to farm size and study assumptionsAdd hepatopancreas to broth to improve test sensitivityJCU Results: 100% PCR test negative for PirA toxin DNASlide7
Assumptions
If prevalence of PirA DNA was >4% at individual prawn level & >25% of ponds affected then our test design was highly likely to find it.Slide8
Disease incursion vs domestic evolution?Epidemiology does not suggest exotic incursionBacteria can acquire new DNA into chromosome through mobile genetic elements like integrons
or transposonsNumerous factors can drive such DNA acquisition egHeavy metal exposureAntibiotic exposureUrgent need to determine risk factors associated with outbreaksIncreased event based sampling warrantedDisinfection response protocol justified