Project number: 2015-037
Project Status:
Budget expenditure: $270,273.00
Principal Investigator: Kate Hodgson
Organisation: SARDI Food Safety and Innovation
Project start/end date: 29 Feb 2016 - 30 Mar 2018


Oyster growing areas with reticulated sewage and/or waste water treatment plants (WWTP) in the catchment are all potentially affected by closures caused by sewage spills and overflows. Standard risk management practice following such events is to instigate a 21 day closure resulting in lost production, market share, reputational damage, and potential recall costs. The number of growing area closures related to sewage spills and overflows in Australia is significant. In NSW, harvest areas were closed on 100 occasions due to sewage spills between July 2009 and June 2014, resulting in 2688 days of lost sales. The use of FRNA phage as potential indicators of human enteric viruses could lead to a 50% reduction in the number of days closed.
In Tas, there have been 75 harvest area closures of greater than 21 days relating to sewage spills over the past 5 years, resulting in at least 1575 days of lost sales. One three week closure in the Pittwater growing area is estimated to cost approx. $250-$400k combined sales, depending on the season. The cumulative impact of these spills has been estimated to reduce the value of businesses by a combined value of $12 million. Not all sewage incidents result in human enteric viral contamination of shellfish. Factors such as the level of illness in the community, treatment level of waste, size of the spill, hydrodynamics of the growing area, and local growing area conditions all influence the whether a spill results in significant contamination of oysters. FRNA phages have not been used routinely as indicators in shellfish in Australia to date. If FRNA phage levels show contamination is negligible, regulators may allow re-opening of growing areas as early as 10 days after the spill following results from testing on day 7, significantly decreasing the cost of spills to growers. FRNA phages are also showing potential as general indicators of human pathogenic risk.


1. Establish baseline levels of FRNA bacteriophages in “at risk” Australian growing areas
2. Determine appropriate sampling plans for FRNA bacteriophages in shellfish following sewage incidents
3. Enable implementation of FRNA phage levels as a management tool for use following adverse sewage incidents in bivalve shellfish growing waters
4. Train laboratories to be competent in using appropriate testing methodologies for FRNA phages in shellfish


ISBN: 978-1-876007-08-9
Authors: Kate Hodgson Valeria Torok Jessica Jolley Navreet Malhi Alison Turnbull
Report • 2018-09-01 • 4.55 MB


The South Australian Research and Development Institute (SARDI) Food Safety and Innovation (FSI) group with the support of the Fisheries Research and Development Corporation (FRDC), TasWater, Central Coast Council, Port Macquarie-Hastings Council, Shoalhaven Council, New South Wales Food Authority (NSWFA), New South Wales Shellfish Program, Oysters Australia and Tasmanian Shellfish Quality Assurance Program (TSQAP) undertook an investigation of the use of FRNA bacteriophages (phages) as indicators of viral contamination in shellfish after adverse sewage events. The human enteric viruses Norovirus (NoV) and Hepatitis A virus (HAV) are the most commonly reported foodborne viral pathogens associated with shellfish. The viruses are bioaccumulated by shellfish when sewage enters water in the growing areas. Oysters were sampled from ‘at-risk’ growing areas to establish background baseline phage levels from July 2016 to December 2017. Five adverse sewage events were also investigated during the same period. In addition, training in the laboratory techniques for phage enumeration was undertaken at the SARDI FSI laboratory in Adelaide for staff from laboratories in NSW and Tasmania.

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