1. Vibrio – what are the risks and consequences for our industry
Alison Turnbull
Shellfish Futures, 16th August 2019

2. Vibriosis Gastroenteritis Wound infection Septicaemia V. vulnificus
50%
Gastroenteritis
Wound infection
Septicaemia
20%
V. vulnificus
V. parahaemolyticus

3. Range and season extension world-wide
80,000 illnesses, 500 hospitalisations and 100 deaths per year in the US*
Increased number of illnesses over last decade
Previously thought of as associated with warm waters
Recent increases in geographic range and seasonal risk extended
Cold-water outbreaks
2004 Alaska 62 people (water temp >15oC) 1000km north of previous illnesses
southern Chile 7,000 cases
2015 BC Canada 73 people (water temp 2oC above summer max)
2019 New Zealand mussels 26 people
* Source: Anna Newton, Magdalena Kendall, Duc J. Vugia, Olga L. Henao, and Barbara E. Mahon 2010

4. Vibrio risk management
Pathogenicity and virulence not well understood
marker genes are usually used to indicate pathogencity, but limited capability in Australia for this type of analysis
Australian risk management advice sparse
ASQAP post harvest temperature control
Pre-harvest not addressed
Food Standards Code advice for ready-to-eat foods based on V. parahaemolyticus levels
100-10,000 cfu/gm unsatisfactory, >10,000 cfu/gm potentially hazardous
Codex recommends monitoring based on pathogenic strains of V. parahaemolyticus, and V. vulnificus and post harvest temp control
NSSP: individual growing area management plans based on epidemiology, monitoring results and environmental variables. Also looks at harvesting techniques
NZ: Harvesting and handling practices used to mitigate V. parahaemolyticus illness, Risk profiles for V. parahaemolyticus, and V. vulnificus
The whole world is struggling to adequately control the risk from Vibrios. USA has a constant and on-going problem, there have been major outbreaks recently cold water areas that are not normally affected, such as Chile.
This is the only hazard that is not adequately dealt with in the Australian program – we haven’t had an issue in the past, although we can no longer say that.
Current best practice is to really know your growing areas – risk assessment for each area – under what conditions do the natural vibrio numbers escalate – is it seasonal, related to temperature, salinity – usually a combination of all of those,
Can we reduce the load by harvesting at certain tide stages
Temperature control post harvest is vital – several models available showing the increase in vibrios with storage, particularly at elevated tempertures. But it isn’t that simple – live animals are more able to keep the vibrio numbers low, so we don’t want to instigate a temperature regime that results in the animals death. E.g. Sydney rock oysters – that is why SRO have a different specification in the ASQAP program for post-harvest temperature control.
Confounding issues – pathogenicity, infectious dose, susceptible individuals

5. What does this mean for you?
SARDI research project to
Survey Tas oyster growing areas
Assess risks for each area
Build lab capability for pathogenicity identification
Know when your risks are greatest
Understand why you are closed
Read the NZ harvest practices advice:
STRICT POST HARVEST TEMPERATURE CONTROL

6. Neogen rapid test kit update
6 growing areas
90 samples – 32 positive, 58 negative
Only 3 samples were above reg limit – all returned positive Neogen results
Positive results were indicative of rising toxin levels
Approx ½ positive results gave high screen results
Some positives at low toxin levels, especially in mussels

7. SafeFish priorities
Better understanding of risk associated with the consumption of raw seafood in Australia
Vibrio species in bivalve seafood
Review of the microbiological criteria relating to seafood in the food standards code
Development of a tropical oyster industry in northern Australia
Seafood Industry Response Plans
Harmful algal blooms (HABs) and their impact on seafood – non- traditional vectors of paralytic shellfish toxins
Ciguatera fish poisoning