1. National survey for foodborne
viruses in Australian oysters
Dr Valeria Torok,
South Australian Research & Development Institute,
Food Safety & Innovation
Shellfish Futures 2014, Smithton, 18th October 2014

2. Norovirus (NoV) - 12-47% illness attributed to food
Symptoms: Vomiting, diarrhoea, abdominal pain, fever, headaches
Incubation period: 10 – 50 hrs
Duration: 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 food
Symptoms: Jaundice, fever, malaise, nausea, abdominal discomfort, dark urine
Incubation 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.

3. SOME FIGURES ON NOROVIRUS
US 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

4. NOROVIRUS IN THE COMMUNITY
(2003-2013)
Data from the Victorian Infectious Diseases Reference Laboratory (VIDRL)
http://www.vidrl.org.au/files/78/noro1306.pdf

5. SHELLFISH RELATED NoV OUTBREAKS
2010-2013
Total of 60 shellfish associated outbreaks reported in NoroNet
Outbreaks related to different genotypes
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
2010 2011 2012 2013
http://www.rivm.nl/dsresource?objectid=rivmp:204484&type=org&disposition=inline

6. AUSTRALIAN OYSTER ASSOCIATED OUTBREAKS
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

7. INTERNATIONAL POLICIES
Codex (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 NoV
European Union (2012)
• Recommended criterion for HAV be implemented (absence) and thresholds for NoV
be developed
Country Requirements/Import Testing
• Some countries do require testing for imports (e.g. Singapore)

8. 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

9. ISO/TS 15216 NoV AND HAV TESTING
Methodology
Virus
Extraction
RNA
Extraction
RT-PCR
Sample
preparation
Analysis
Proteinase K
Elution and precipitation
with PEG/NaCl

10. 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.

11. Proficiency trial results

12. 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

13. THE STEERING COMMITTEE
A steering committee consisting of state shellfish regulators and growers
was established at the onset of the project
Chair
Anthony Zammit NSW Food Authority, NSW
Members
Jane Clout Kooringal Oysters, Queensland
Rachel King Oysters Australia, National
Trudy McGowan SAORC, South Australia
Rebecca Schofield SafeFood, Queensland
Tony Troup Camden Haven Oysters, New South Wales
Clinton Wilkinson SASQAP, South Australia
Howel Williams Department of Health and Human Services, Tasmania
Jon Poke Bolduans Bay Oysters, Tasmania
Permanent Observers and Secretariat
Valeria Torok SARDI and Principal Investigator
Alison Turnbull SARDI/SafeFish

14. 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.

15. 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/

16. 41.8
Oyster sampling plan based on
national production
% Oyster production nationally ($) Total samples allocated to state
22.3
• “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.
35.4
0.5
125
67
106
2
NSW Tas SA Qld

17. 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

18. TASMANIAN SAMPLING PLAN
8.6
6.6
17.8
6.5
16.9
27.2
16.4
D Entrecasteaux
Channel
Far North West
Georges Bay
Great Oyster Bay
Tasman Peninsula
Pipe Clay Lagoon
DPIPWE data 2008- 2012. Data used was based
on total dozens.
Pitt Water
Proportion of Tasmanian
oyster production (%)

19. Acknowledgements
SARDI 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)