Norovirus and FRNA bacteriophage determined by RT-qPCR and infectious FRNA bacteriophage in wastewater and oysters John Flannery a , Sine ´ad Keaveney a , Paulina Rajko-Nenow a , Vincent O’Flaherty b , William Dore ´ a, * a Marine Institute, Rinville, Oranmore, Co., Galway, Ireland b Microbial Ecology Laboratory, Microbiology, School of Natural Sciences and Ryan Institute, National University of Ireland, Galway, Ireland article info Article history: Received 30 January 2013 Received in revised form 14 May 2013 Accepted 2 June 2013 Available online 24 June 2013 Keywords: Wastewater treatment Norovirus UV disinfection Virus removal RT-qPCR FRNA bacteriophage Oysters abstract Norovirus (NoV), the leading cause of adult non-bacterial gastroenteritis can be commonly detected in wastewater but the extent of NoV removal provided by wastewater treatment plants (WWTPs) is unclear. We monitored a newly commissioned WWTP with UV disin- fection on a weekly basis over a six month period for NoV using RT-qPCR and for FRNA bacteriophage GA using both RT-qPCR (total concentration) and a plaque assay (infectious concentration). Mean concentrations of NoV GI and GII in influent wastewater were reduced by 0.25 and 0.41 log 10 genome copies 100 ml 1 , respectively by the WWTP. The mean concentration of total FRNA bacteriophage GA was reduced by 0.35 log genome copies 100 ml 1 compared to a reduction of infectious FRNA bacteriophage GA of 2.13 log PFU 100 ml 1 . A significant difference between concentrations of infectious and total FRNA bacteriophage GA was observed in treated, but not in untreated wastewaters. We conclude that RT-qPCR in isolation underestimates the reduction of infectious virus during wastewater treatment. We further compared the concentrations of infectious virus in combined sewer overflow (CSO) and UV treated effluents using FRNA bacteriophage GA. A greater percentage (98%) of infectious virus is released in CSO discharges than UV treated effluent (44%). Following a CSO discharge, concentrations of NoV GII and infectious FRNA bacteriophage GA in oysters from less than the limit of detection to 3150 genome copies 100 g 1 and 1050 PFU 100 g 1 respectively. ª 2013 Elsevier Ltd. All rights reserved. 1. Introduction Norovirus (NoV) is the most significant cause of non-bacterial gastroenteritis in the developed world (Mead et al., 1999). NoV infections cause a number of symptoms including diarrhoea, nausea, vomiting and abdominal pain (Turcios et al., 2006), which can have complications for immunocompromised individuals (Schwartz et al., 2011). Faeces from infected per- sons can contain NoV concentrations of up to 10 8 copies g 1 (Lee et al., 2007) and thus NoV is commonly present in municipal wastewater (Da Silva et al., 2007; Flannery et al., 2012; Katayama et al., 2002). The discharge of municipal wastewater into the marine environment is a common prac- tice worldwide and is a major source of faecal contamination * Corresponding author. Tel.: þ353 91 387224; fax: þ353 91 387201. E-mail addresses: jbflannery@gmail.com (J. Flannery), bill.dore@marine.ie (W. Dore ´). Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/watres water research 47 (2013) 5222 e5231 0043-1354/$ e see front matter ª 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.watres.2013.06.008