Evaluation of Removal of Noroviruses during Wastewater Treatment, Using Real-Time Reverse Transcription-PCR: Different Behaviors of Genogroups I and II

Abstract

Noroviruses, an important cause of gastroenteritis, are excreted by infected individuals and are therefore present in wastewater. We quantified norovirus genogroup I (GI) and GII in wastewater at different locations in France and evaluated removal by a range of treatment types, including basic (waste stabilization pond), current industry standard (activated sludge), and state-of-the-art (submerged membrane bioreactor) treatments. Noroviruses were quantified using real-time reverse transcription-PCR (rRT-PCR). Mengovirus was used as a virus extraction control, and internal controls were used to verify the level of GI and GII rRT-PCR inhibition. A total of 161 (81 influent and 79 effluent) samples were examined; GI and GII were detected in 43 and 88% of the influent samples, respectively, and in 24 and 14% of the effluent samples, respectively. Physicians in France report far more cases of GII than GI during outbreaks; thus, the frequent presence of GI was unexpected. The GI influent concentrations were more variable, the peak GI influent concentrations were higher than the peak GII influent concentrations at all four sites (up to 1 ؋ 10 9 and 6 ؋ 10 7 genome copies/liter, respectively), and the average positive influent concentrations of GI were higher than the average positive influent concentrations of GII. The maximum effluent breakthrough concentrations were 6 ؋ 10 6 and 3 ؋ 10 6 genome copies/liter for GI and GII, respectively, indicating that the four treatment systems studied decreased the norovirus contamination load in receiving waters.Noroviruses, the leading cause of gastroenteritis worldwide, are extremely genetically diverse (2, 5, 33). Members of the Caliciviridae family, they are subdivided into five genogroups (genogroup I [GI], GII, GIII, GIV, and GV), and GI, GII, and GIV have been detected in humans (42). GII has been shown to account for the majority (up to 92%) of reported norovirus gastroenteritis cases, and GI accounts for the large majority of the remaining cases (2,5,22). Norovirus infections occur throughout the year, but there is a large annual peak of gastroenteritis during the cold winter months (27). Although the illness is generally self-limiting in otherwise healthy individuals, the high incidence of norovirus cases imposes a high cost on society (24). Besides person-to-person transmission, food contaminated by sewage, such as oysters, berries, or water, has been implicated in outbreaks, although often the source cannot be determined (10,33,41). Noroviruses have been shown to be resistant to wastewater treatment (17,28,30,36,38,39) and have been detected in wastewater-polluted water, as well as shellfish (19,20,26,36).Currently, molecular detection is the only method for detection of noroviruses, but their genetic diversity has made genomic detection of these viruses a challenge (1, 2). Recently developed broadly reactive one-step real-time reverse transcription PCR (rRT-PCR) assays have allowed sensitive detection (13,21,35,37), although precise quantification of environmental sam...

Diverse norovirus genotypes identified in sewage-polluted river water in South Africa

“…In this and other studies [13,23], GI strains were detected at similar frequencies to GII strains in the environment. This indicates that GI viruses might be as prevalent in the population as GII strains but may cause less severe disease or asymptomatic infection.…”

Health risk implications from simultaneous exposure to multiple environmental contaminants

“…The detection and gene coding of all strains of V. cholerae was performed according to the procedures described by Le Roux and Van Blerk (2011). The water samples were analysed for the presence of Enterovirus and Norovirus according to methods described in Da Silva et al (2007), Fuhrman et al (2005) and Loisy et al (2005). Analysis for protozoan parasitic (Giardia sp.…”

Emerging norovirus GII.4 2008 variant detected in hospitalised paediatric patients in South Africa

“…Published primer sets, Taqman probes and the QuantiTect Probe RT-PCR kit (Qiagen Inc., Valencia, CA) were used to detect NoV GI 20,21 or GII 22,23 and SaV. 24 For genotyping the 5 end of the NoV capsid gene (Region C) was amplified and sequenced.…”