National survey for foodborne viruses in Australian oysters

Dr Valeria Torok, South Australian Research & Development Institute, Food Safety & InnovationShellfish Futures 2014, Smithton, 18th October 2014

Norovirus (NoV) - 12-47% illness attributed to foodSymptoms: Vomiting, diarrhoea, abdominal pain, fever, headachesIncubation period: 10 – 50 hrsDuration: 24 – 60 hrs

•High levels of virus excreted in faeces (≤1011 virus particles/g) for up to 2-3 weeks•Low median infectious dose (18 virus particles)

•probability of becoming ill in susceptible individuals is dose-dependent.•Immunity to the virus is often short lived•New pandemic every 2-3 years•No effective vaccine against human NoV•Unable to culture human NoV

Hepatitis A virus (HAV) – 5% illness attributed to foodSymptoms: Jaundice, fever, malaise, nausea, abdominal discomfort, dark urineIncubation period: 15-50 days. Duration: 2 months

•High levels excreted in faeces 2 wks before symptoms & for 4 wks during symptoms.•Infectious dose low (presumed to be 10-100 virus particles)•Effective vaccination available.•Can be cultured in vitro.

SOME FIGURES ON NOROVIRUSUS figures

• Fourth most common pathogen causing foodborne deaths

Australian figures• 17.2 million cases of gastroenteritis per year (circa 2000)

NoV main cause of outbreak-associated gastroenteritis (GII.4 responsible for 85%)

15% of outbreaks are food associated (~2.5 mill)

• 1988 - 2001 most significant cause of seafood related illness • 2001- 2011 ranked third in seafood related illness

NOROVIRUS IN THE COMMUNITY (2003-2013)

Data from the Victorian Infectious Diseases Reference Laboratory (VIDRL)http://www.vidrl.org.au/files/78/noro1306.pdf

SHELLFISH RELATED NoV OUTBREAKS 2010-2013

Total of 60 shellfish associated outbreaks reported in NoroNetOutbreaks related to different genotypes

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2010 2011 2012 2013

http://www.rivm.nl/dsresource?objectid=rivmp:204484&type=org&disposition=inline

Year Origin Cases Virus

1978 Georges River >2000 Norovirus

1996 Terranora Lake 97 Norovirus

1997 Wallis Lake ~400 (1) Hepatitis A virus

2008 Kalang River ~30 Norovirus

2012 Camden ~36 Norovirus

2013 Dunalley ~500 Norovirus

2000 – 2010 Australia wide ~18 outbreaks Norovirus

AUSTRALIAN OYSTER ASSOCIATED OUTBREAKS

INTERNATIONAL POLICIESCodex (Food Hygiene Committee) • “Guidelines on the application of general principles of food hygiene to the control of

viruses in food (CAC/GL 79-2012)”

Annex I: Control of HAV & NoV in bivalve molluscs

Annex II: Control of HAV & NoV in fresh produce

USFDA, Health Canada, CFIA Risk Assessment• Aims to set Performance Objectives (levels at retail) & Food Safety Objectives (levels

at consumption) for NoVEuropean Union (2012)• Recommended criterion for HAV be implemented (absence) and thresholds for NoV

be developedCountry Requirements/Import Testing• Some countries do require testing for imports (e.g. Singapore)

INTERNATIONAL STANDARD FOR TESTING ISO/TS 15216

• Based on detection of viral RNA genome (RT-PCR)

• Requires removal of inhibitory substances present in food matrices

• Development of a standard method has allowed comparability of results among laboratories

• International proficiency trials

ISO/TS 15216 NoV AND HAV TESTING

Methodology

Virus Extraction

RNA Extraction RT-PCRSample

preparation Analysis

Proteinase KElution and precipitation with PEG/NaCl

Centre for Environment, Fisheries & Aquaculture Science (CEFAS) proficiency testing scheme, 2013

European Union Reference Laboratory (EURL) Proficiency Testing Scheme for NoV and HAV in bivalve

molluscan shellfish

44 laboratories received samples 17 national reference laboratories 27 other laboratories

Materials dispatched • bioaccumulated Pacific oysters (Samples 1-3)• bioaccumulated common mussels (Sample 4)• laboratory constructed LENTICULES™ (Vials 1 & 2)• dsDNA control material for quantification.

Proficiency trial results

SURVEY OF FOODBORNE VIRUSES IN AUSTRALIAN OYSTERS

Norovirus (NoV) levels need to be contextualised against a baseline

• EU moving towards mandatory virus monitoring (in UK 76% of production areas are positive for NoV).

• To avoid similar regulation we need to show we don’t have a problem

USA, UK, France and China have done NoV surveys (reported prevalence ranges between 4 – 76%)

Determination of Australian NoV baseline • Could provide an argument against mandatory testing

i.e. if baseline < 2% prevalence

• Could be used to inform improved management where required

THE STEERING COMMITTEEA steering committee consisting of state shellfish regulators and growers was established at the onset of the project

ChairAnthony Zammit NSW Food Authority, NSW

MembersJane Clout Kooringal Oysters, QueenslandRachel King Oysters Australia, NationalTrudy McGowan SAORC, South AustraliaRebecca Schofield SafeFood, QueenslandTony Troup Camden Haven Oysters, New South WalesClinton Wilkinson SASQAP, South AustraliaHowel Williams Department of Health and Human Services, TasmaniaJon Poke Bolduans Bay Oysters, Tasmania  Permanent Observers and SecretariatValeria Torok SARDI and Principal InvestigatorAlison Turnbull SARDI/SafeFish

ROLES OF THE STEERING COMMITTEE• Provide strategic oversight to ensure project outputs continue

to contribute to enhanced capability for management of foodborne viruses in oysters.

• Assist with communicating research to regulators and growers

• Assist with communicating results of the study to industry and other stakeholders to ensure successful delivery of research outcomes.

• Provide guidance to project researchers and industry on protocols for handling commercially- or market-sensitive information arising from the project.

• Assist with advice on reporting policy.

• Provide feedback on sampling design and protocol, and help with sample collection.

SURVEY OF FOODBORNE VIRUSES IN AUSTRALIAN OYSTERS

Survey Design– Oysters sourced at the production area level– Main oyster producing states: NSW, SA, TAS & Qld– Sampling reflects states productivity– 150 samples collected each in winter/spring and summer/autumn

(n=300)• This will enable detection of viruses if present at < 2% prevalence

– Viruses investigated are Norovirus (GI & GII) and Hepatitis A virus using the international standard for testing (ISO/TS 15216)

Fact sheet on the project can be found at:http://oystersaustraliablog.org.au/green-light-for-new-rd-projects/

• “ABARES fisheries production for oysters” based on $ value. • Sample numbers within states were informed by production data from

growing areas and further to harvest areas.• Leases sampled within harvest areas were selected randomly but

weighted on % production.

NSW Tas SA Qld

41.822.3

35.4

0.5

125

67

106

2

Oyster sampling plan based on national production

% Oyster production nationally ($) Total samples allocated to state

SURVEY OF FOODBORNE VIRUSES IN AUSTRALIAN

OYSTERS

Number of oyster samples collected from various Australian Oyster production areas per season (winter/spring or summer/autumn)

• Winter/spring sampling commenced in July and will finish in September

• Sample numbers assigned to harvest areas were determined by production data

• Sample collections within harvest area has been randomly determined

TASMANIAN SAMPLING PLAN

DPIPWE data 2008- 2012. Data used was based on total dozens.

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Pitt

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8.6 6.6

17.8

6.5

16.9

27.2

16.4

Proportion of Tasmanian oyster production (%)

AcknowledgementsSARDI staff - Catherine McLeod, Alison Turnbull, Kate Hodgson, Jessica Tan, Navreet Malhi, Linda Friedrich, Joanne Tomkins

Steering Committee - Anthony Zammit, Jane Clout, Rachel King, Trudy McGowan, Rebecca Schofield, Tony Troup, Clinton Wilkinson, Howel Williams, Jon Poke

Oyster growers and samplers - Jeff Whayman, Jon Poke, Craig Lockwood, Hayden Dyke, Mike Webb, Justin Goc, Tom Gray

Funders - FRDC, NSW Food Authority, South Australian Shellfish Quality Assurance Program (SASQAP), South Australian Oyster Research Council (SAORC), Tasmanian Oyster Research Council (TORC) and Tasmanian Shellfish Executive Council (TSEC)