Environmental surveillance of norovirus in Argentina revealed distinct viral diversity patterns, seasonality and spatio-temporal diffusion processes

• Published in: The Science of the total environment 2012-10, Vol.437, p.262-269
• Main Authors: Fernández, María D. Blanco, Torres, Carolina, Poma, Hugo R., Riviello-López, Gabriela, Martínez, Laura C., Cisterna, Daniel M., Rajal, Verónica B., Nates, Silvia V., Mbayed, Viviana A.
• Format: Article
• Language: English
• Subjects: Argentina - epidemiology; Bacteriology; Base Sequence; Biodiversity; Biological and medical sciences; Caliciviridae Infections - epidemiology; Caliciviridae Infections - transmission; Cities; Diffusion; Ecological risk assessment; Environmental Monitoring; Environmental virology; Estimating; Fecal contamination; Fundamental and applied biological sciences. Psychology; Genetic Variation; Genomes; Genotype; Human viral diseases; Humans; Infectious diseases; Medical sciences; Microbiology; Models, Biological; Molecular Sequence Data; Norovirus; Norovirus - classification; Norovirus - genetics; Norovirus - isolation & purification; Pathogenicity, virulence, toxins, bacteriocins, pyrogens, host-bacteria relations, miscellaneous strains; Phylogeny; Phylogeography; Populations; Rivers; Rivers - virology; Seasons; Sequence Analysis, DNA; Sewage - virology; Surveillance; Viral diseases; Viral diseases of the digestive system; Viruses
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2012.08.033

Norovirus (NoV) contamination was evaluated in five rivers of Argentina between 2005 and 2011. NoV was present in all sampled rivers, with distinct NoV patterns in waters impacted by different-sized communities. In rivers affected by medium-sized populations (Salta and Córdoba cities) only one or two genotypes were present, GII.4 being the main one, with winter seasonality. In contrast, in the much more heavily populated area of Buenos Aires city the prevalent GII.4 was accompanied by several additional genotypes (GII.4, GII.b, GII.2, GII.7, GII.17, GII.e and GII.g) and one ungenotyped GII NoV, with no clear seasonality. GII.4 2006b was the main variant detected (60.9%). Phylogeographic and phylodynamic analyses performed in region D of the VP1 gene showed a most recent common ancestor in 2002 and a substitution rate of 3.7×10−3 substitutions per site per year (HPD95%=2.3×10−3−5.2×10−3) for this variant still involving a significant population size with a slight decrease since 2008. The spatio-temporal diffusion analysis proposed Europe as an intermediate path between the American Continent and the rest of the World for NoV dissemination. Given the importance of NoV as a cause of epidemic gastroenteritis and the likelihood of its environmental transmission, the results of this work should increase public and institutional awareness of the health risk involved in sewage discharges into the environment. Environmental surveillance of enteric viruses could be a very useful tool not only to prevent waterborne outbreaks, but also to describe the epidemiology of the viruses. The detailed analysis of the viral genomes disposed into the environment contributed to the characterization of the dissemination, diversity and seasonality of NoV in its natural host population. In future studies, environmental surveillance and molecular analysis should be complemented with a quantitative viral risk assessment for estimating the disease burden from viruses in the environment. ► Environmental presence of norovirus (NoV) was detected in five rivers from Argentina. ► Distinct NoV patterns were observed in rivers impacted by different-sized communities. ► Environmental surveillance revealed viral dissemination, diversity and seasonality. ► A geographically structured viral population was observed for GII-4 2006b variant. ► A route for global NoV dissemination is proposed with Europe as an intermediate path.