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The Survival of Noroviruses and Potential Viral Indicators in Sewage Treatment Processes and in the Marine Environment

Centre for Environment, Fisheries and Aquaculture Sciences (CEFAS)
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This research study aims to provide information on the survival and behaviour of Noroviruses and potential viral indicators in sewage treatment and marine environments.

The main objectives of this project will be to provide information on:

  • the occurrence of NV in sewage effluents;
  • the inactivation/removal of NV during passage through conventional biological sewage treatment;
  • the survival characteristics of NV in the sea following effluent discharge;
  • the linkage between NV discharge in effluents and their uptake in shellfish;
  • and the relationship of NV during the above studies to other more commonly monitored enteric viruses (enteroviruses), conventional faecal pollution indicators (E. coli) and a potential viral indicator (FRNA bacteriophage).

Initial work will focus on the development of a quantitative Polymerase Chain Reaction (PCR) assay to detect NV strains in sewage effluent using a real time fluorogenic 5' nuclease assay (TaqMan).

The NV occurrence in sewage effluent and inactivation/removal during treatment will be examined at three sewage treatment works, all sampled fortnightly for crude sewage, primary and final effluents over a one year period.

In addition, at two of the sewage treatment works, virus presence in discharged effluent will be compared with virus presence in shellfish laid at an adjacent field site. NV occurrence will also be compared with enterovirus and FRNA bacteriophage by TaqMan PCR and with the indicator organisms E. coli and FRNA bacteriophage by viability assay.

The survival of NV in marine water will be investigated by seeding virus into seawater in the laboratory and measuring the degradation of NV over time using the developed TaqMan assay.

NV inactivation will be compared with poliovirus, FRNA bacteriophage and E. coli.

The inactivation kinetics of these organisms will also be investigated under simulated winter (low light and temperature) and summer (high light and temperature) conditions.

Sunlight will be simulated using a solar simulator with the correct balance of UVA and UVB found in natural sunlight in England.

More information
In the UK the main food safety risk associated with the consumption of bivalve molluscs is gastroenteritis caused by Noroviruses (NV).

The protection of vulnerable shellfisheries is heavily dependent on adequate sewage treatment and inactivation of any residual pathogen load through effective dilution/dispersion of effluent in the sea following discharge.

NV are non-culturable and molecular methods for their detection have only recently been developed. As a result, despite their acknowledged importance as agents of viral illness, virtually nothing is known about their inactivation/removal during sewage treatment or survival in the environment.

Monitoring data from conventional bacterial faecal pollution indicators (such as E. coli) is used to inform decisions on sewage treatment, location of discharges and priority given to intermittent discharges (such as combined storm overflows).

It is however not known whether such indicators adequately reflect the behaviour and survival of NV.

Find more about this project and other FSA food safety-related projects at the Food Standards Agency Research webpage.

Funding Source
Food Standards Agency
Project number
Natural Toxins
Viruses and Prions
Bacterial Pathogens
Chemical Contaminants
Escherichia coli