Pathogenic Enteric Viruses and Microbial Indicators during Secondary Treatment of Municipal Wastewater

Abstract

c Pathogenic enteric viruses are responsible for a wide range of infections in humans, with diverse symptoms. Raw and partially treated wastewaters are major sources of environmental contamination with enteric viruses. We monitored a municipal secondary wastewater treatment plant (New Orleans, LA) on a monthly basis for norovirus (NoV) GI and GII and enterovirus serotypes using multiplex reverse transcription-quantitative PCR (RT-qPCR) and microbial indicators of fecal contamination using standard plating methods. Densities of indicator bacteria (enterococci, fecal coliforms, and Escherichia coli) did not show monthly or seasonal patterns. Norovirus GII was more abundant than GI and, along with enterovirus serotypes, increased in influent during fall and spring. The highest NoV GI density in influent was in the fall, reaching an average of 4.0 log 10 genomic copies/100 ml. Norovirus GI removal (0.95 log 10 ) was lower than that for GII, enterovirus serotypes, and male-specific coliphages (1.48 log 10 ) or for indicator bacteria (4.36 log 10 ), suggesting higher resistance of viruses to treatment. Male-specific coliphages correlated with NoV GII densities in influent and effluent (r ‫؍‬ 0.48 and 0.76, respectively) and monthly removal, indicating that male-specific coliphages can be more reliable than indicator bacteria to monitor norovirus GII load and microbial removal. Dominant norovirus genotypes were classified into three GI genotypes (GI.1, GI.3, and GI.4) and four GII genotypes (GII.3, GII.4, GII.13, and GII.21), dominated by GI.1 and GII.4 strains. Some of the seasonal and temporal patterns we observed in the pathogenic enteric viruses were different from those of epidemiological observations. E nteric viruses are responsible for a wide range of infections in humans with diverse symptoms. Infected individuals shed millions of virus particles in their feces or body fluids, which eventually enter sewage systems. Enteric viruses may naturally occur in aquatic environments as well, but human activities, in particular, sewage discharge, is the primary source of environmental contaminants (1-3). Among the pathogenic enteric viruses, norovirus (NoV), enterovirus (EV), adenovirus, astrovirus, and rotavirus have been found frequently in municipal wastewaters worldwide (1, 4-6). Several gastroenteritis outbreaks have been linked directly or indirectly to human exposure of raw or partially treated sewage-contaminated water or foods (2).Municipal wastewaters usually undergo a secondary treatment before being discharged into the environment. The process involves a mechanical treatment for removing solids followed by biological and chemical treatments, nutrient removal, and discharge (7). Primary-treated (physically processed) wastewater or the effluent water that does not undergo a disinfection process may still harbor infectious enteric viruses, similar to the raw sewage (4, 8). To protect water quality and public safety, fecal coliforms and Escherichia coli have been used to monitor fecal pollution in wastewater dis...

Differential removal of human pathogenic viruses from sewage by conventional and ozone treatments

“…Human-related viruses were strongly reduced by conventional treatment of the sewage, and the elimination of several of these was achieved by additional ozone treatment. Other studies have previously shown reduction of parasitic protozoa, bacteria, and phages by conventional treatment of sewage (Ottoson et al, 2006a;Tyrrell et al, 1995), but little was known regarding the reduction of human enteric viruses (Montazeri et al, 2015;Ottoson et al, 2006b,c) or their sensitivity to ozonation of sewage. While ozonation is already recognized as a promising technology for removing microcontaminants, such as pharmaceuticals, in sewage (Beijer et al, 2017), the additional benefit of reducing risks for the spread of human pathogenic viruses via Fig.…”

Membrane Bioreactor-Based Wastewater Treatment Plant in Saudi Arabia: Reduction of Viral Diversity, Load, and Infectious Capacity

“…Myrmel and coworkers detected 10 5.8 to 10 6.2 genomic copies/L of AdV in a study conducted in Norway [37], while Kuo et al detected approximately 3.8 ± 0.5 × 10 5 viral particles per liter of raw sewage in Taiwan [38]. Similarly, EV concentrations ranged from 10 2.7 copies/L in a New Orleans, US study [39] and as high as 1.5 × 10 5 to 1.2 × 10 8 copies per L in an analysis done in Japan [3]. Similar to the findings from earlier studies [34,40], there was a lack of strong correlation between the abundance of fecal coliforms and human enteric viruses.…”

Molecular epidemiology and host genetics of norovirus and rotavirus infections in Portuguese elderly living in aged care homes

“…Circulation of GI.3 was notified in Portugal since 2013, from an AGE outbreak in Portuguese military . Curiously, GI.3 sequences from our study clustered with a NoV strain identified in wastewater in the United States during 2014 (Figure A). Interestingly, the GII strain identified was not the globally predominant GII.4, also previously described in Portugal on several outbreaks, but GII.6, to our knowledge, notified in the country for the first time.…”