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

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

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 2004-2007 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

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

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: https://www.teururakau.govt.nz/dmsdocument/27729/direct STRICT POST HARVEST TEMPERATURE CONTROL

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

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