Genetic diversity of noroviruses in raw and treated sewage water

• Published in: Research in microbiology Vol. 156; no. 4; pp. 532 - 540
• Main Authors: van den Berg, Harold, Lodder, Willemijn, van der Poel, Wim, Vennema, Harry, de Roda Husman, Ana Maria
• Format: Journal Article
• Language: English
• Published: Paris Elsevier SAS 01-05-2005; Elsevier
• Subjects: Biological and medical sciences; Calicivirus; Environmental Monitoring; Fundamental and applied biological sciences. Psychology; Genetic Variation; Microbiology; Miscellaneous; Netherlands; Norovirus; Norovirus - genetics; Norovirus - isolation & purification; Phylogeny; Reverse Transcriptase Polymerase Chain Reaction; RNA, Viral - analysis; RNA, Viral - genetics; Sequence; Sewage; Sewage - analysis; Sewage - virology; Treatment; Virology; Waste Disposal, Fluid; Netherlands; Calicivirus; Norovirus; Sewage; Treatment; Sequence; Virus; Microbiology; Caliciviridae; Genetic diversity
• ISSN: 0923-2508; 1769-7123
• DOI: 10.1016/j.resmic.2005.01.008

Human noroviruses cause gastroenteritis in humans, leading to high virus loads in sewage. Norovirus concentrations in raw and treated sewage samples from two sewage treatment plants (STP) were studied, along with virus removal and genetic diversity. Over one year, the average norovirus concentrations in raw sewage were approximately
10
5

pcr
detectable units (pdu) per liter compared with
10
3

pdu
/
l
of treated sewage. Similar sewage treatment processes at STP-A and STP-B led to 2.7 and
2.0
log
10
-units of virus removal, respectively. In total, 11 different norovirus variants were detected in 49 out of 53 sewage samples, with up to four different norovirus strains in a single sewage sample. Along with GGI.6 Sindlesham and GGII.2 Melksham, the GGIIb variant was one of the most prevalent noroviruses in both raw and treated sewage. This strain emerged among populations in Europe in 2000 and 2001. Treated sewage containing 10
2–10
3 norovirus pdu is discharged into the surface water. The use of such fecally contaminated surface waters for shellfish culture, drinking water production and recreational purposes poses a potential health risk. We showed the presence of multiple norovirus strains in raw and treated sewage, confirming the need to clone before sequencing the RT-PCR products. Exposure to multiple norovirus strains in sewage contaminated food or water may lead to the occurrence of norovirus recombinants, which may be more virulent and pathogenic than the norovirus strains already circulating in the population.