STRIVE 109 - Bill Dore, John Flannery, Sinead Keaveney, Paulina Rajko-Neneow
Summary: This project looks at the effect of waste waster discharges containing Norovirus on shelfish
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Norovirus (NoV) is the most common cause of viral gastroenteritis in the developed world. It is spread through the faecal–oral route and generally causes self-limiting diarrhoea in healthy individuals, although more serious illness may occur in immunocompromised individuals. Municipal wastewater contains significant concentrations of NoV. Therefore, the discharge of municipal wastewater into
the marine environment, as practised throughout the world, has implications for the virus quality of shellfish production areas.
Bivalve shellfish, such as oysters and mussels, can accumulate NoV from contaminated water. Oysters are frequently consumed raw and have been associated with outbreaks of gastroenteritis when they are grown in areas impacted by municipal wastewater discharges. Wastewater treatment plants (WWTPs) can be effective in reducing the bacterial concentration in wastewater and are considered an important control point in protecting the microbiological quality of shellfish production areas. However, the extent to which wastewater treatment (WWT) reduces NoV concentrations is unclear.
This study used a realtime reverse-transcription quantitative polymerase chain reaction (RT-qPCR) to investigate the reduction of NoV during the treatment provided by two WWTPs and the subsequent accumulation in oysters. The use of UV disinfection processes was also investigated to determine whether an additional level of NoV reduction could be achieved. In addition, the contribution of combined sewer overflow (CSO) discharges to NoV contamination in oysters was investigated. Finally, the survival of NoV in sea water under winter and summer conditions was also investigated. In addition to directly detecting NoV, F-specific RNA (FRNA) bacteriophage was used as an indicator of virus behaviour throughout the study. Concentrations of FRNA bacteriophage
were determined using both a RT-qPCR and a plaque assay to provide a direct comparison between an infectivity assay and the RT-qPCR assay.