1. Penaeus monodon mortality syndrome (PMMS) Early mortality syndrome (EMS) Acute hepatopancreatic necrosis disease (AHPND)
Dr Matt Landos
Director, Future Fisheries Veterinary Service Pty Ltd
Kelly Condon
James Cook University

3. Potted International history AHPND
Emerged from China in ~ of new disease
Vague 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 EMS
Pathology caused by PirAB toxin production from a Vibrio in stomach
OIE definition initially confined to Vibrio parahaemolyticus, soon to be broadened to include other Vibrio’s and plasmid
Now reported in Vibrio harveyi also in Asia and Australia
In Asia PirAB toxin associated with a plasmid (ie independent of bacterial DNA)
In Australia, PirAB not associated with a plasmid, it is part of chromosome

4. Clinical signs of AHPND
Hepatopancreas (HP) often pale to white due to pigment loss in the connective tissue capsule
Significant atrophy (shrinkage) of HP
Often soft shells and guts with discontinuous contents or no content
Black spots or streaks sometimes visible within the HP
HP does not squash easily between thumb and finger
Onset of clinical signs and mortality starting as early as 10 days post- stocking
Moribund shrimp sink to the bottom

5. PMMS Outbreaks

6. PMMS screening 2016 13 farms from Northern NSW to Far north Qld
980 samples
All P monodon sampled for PCR and tissue stored for histology
Targeted prawns with signs of poor health
10 prawns per pond
Pond numbers varied relative to farm size and study assumptions
Add hepatopancreas to broth to improve test sensitivity
JCU Results: 100% PCR test negative for PirA toxin DNA

7. 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.

8. Disease incursion vs domestic evolution?
Epidemiology does not suggest exotic incursion
Bacteria can acquire new DNA into chromosome through mobile genetic elements like integrons or transposons
Numerous factors can drive such DNA acquisition eg
Heavy metal exposure
Antibiotic exposure
Urgent need to determine risk factors associated with outbreaks
Increased event based sampling warranted
Disinfection response protocol justified