Public Health Concerns about Caliciviruses as Waterborne Contaminants

Noroviruses have received increased attention in recent years because their role as etiologic agents in acute gastroenteritis outbreaks is now clearly established. Our inability to grow them in cell culture and the lack of an animal model hinder the characterization of these viruses. More recently, molecular approaches have been used to study the genetic relationships that exist among them. In the present study, environmental samples from seawater, estuarine water, and effluents of sewage treatment plants were analyzed in order to evaluate the role of environmental surface contamination as a possible vehicle for transmission of norovirus genogroups I and II. Novel broad-range reverse transcription-PCR/nested assays targeting the region coding for the RNAdependent RNA polymerase were developed, amplifying fragments of 516 bp and 687 bp in the nested reactions for genogroups II and I, respectively. The assays were evaluated and compared against widely used published assays. The newly designed assays provide long regions for high-confidence BLAST searches in public databases and therefore are useful diagnostic tools for molecular diagnosis and typing of human noroviruses in clinical and environmental samples, as well as for the study of molecular epidemiology and the evolution of these viruses.

mentioning

confidence: 99%

Molecular Identification and Genetic Analysis of Norovirus Genogroups I and II in Water Environments: Comparative Analysis of Different Reverse Transcription-PCR Assays

Rosa

Fontana

Grazia

et al. 2007

“…The high prevalence of NoV genogroup I (GI) in wastewaters and treated effluents (4,16) raises questions of environmental stability and resistance to wastewater treatment. Less is known about the circulation of NoV in other waters (22,28,30), although the importance of viral contamination from sewage effluents in shellfish growing areas is well recognized (2,18).…”

mentioning

confidence: 99%

Tracing of Norovirus Outbreak Strains in Mussels Collected near Sewage Effluents

Nenonen

Hannoun

Horal

et al. 2008

Noroviruses from mussels collected near sewage effluents were compared with local patient outbreak strains. Sequence analyses of RNA polymerase-capsid-poly(A)-3 (3.1-kilobase) regions confirmed the 99.9% similarity between genotype I.1 strains from mussels and patient strains from recreational-bathing outbreaks, indicating the potential usefulness of sentinel norovirus mussel studies in tracing human norovirus contamination of coastal waters.

“…NLVs are highly infectious, with a minimal infectious dose of an estimated 10 to 100 virus particles (33,38), and are frequently responsible for foodborne outbreaks due to contaminated water, ready-to-eat dishes, seafood, fruits, and vegetables (2,4,5,7,8,10,14,16,20,21,24,26,28,31; J. N. Kuritsky, M. T. Osterholm, J. A. Korlath, K. E. White, and J. E. Kaplan, Letter, J. Infect.…”

mentioning

confidence: 99%

Norwalk-Like Virus Sequences in Mineral Waters: One-Year Monitoring of Three Brands

Beuret

Kohler

Baumgärtner

et al. 2002

138

In a recent study, RNA with nucleotide sequeces specific for "Norwalk-like viruses" (NLV) was detected in 11 different brands of European mineral waters. To clarify this finding, a 1-year monitoring study was conducted. Samples of three European brands of mineral water without gas were monitored weekly by reverse transcriptase PCR using generic and genogroup-specific oligonucleotides. Additional analyses were performed to investigate a possible correlation between NLV sequence contamination and mineral water lot numbers, the long-term stability (persistence) of NLV sequences in mineral water, and the level of contamination. NLV sequences were detected in 53 of 159 samples analyzed (33%) and belonged entirely to genogroup II. Although all NLV strains identified were closely related, three mineral water brand-specific clusters could be identified for both primer systems by sequencing. Analyses of second samples from lots previously shown to be positive for NLV sequences gave corresponding results in 45 of 53 cases (85%) (within a six-pack). NLV persistence was tested by analyzing 10 positive samples after 6 and 12 months of storage in darkness at room temperature. After 6 months, all samples remained positive; after 12 months, 9 of 10 samples were still positive for NLV sequences. No NLV sequences could be detected by analysis of 0.1-liter aliquots of 53 samples shown to be positive by testing of 1-liter volumes. Based on this fact and a test sensitivity of approximately 10 viral units, levels of contamination in positive mineral water samples were estimated to be in the range of 10 to 100 genomic equivalents per liter.