Capturing noroviruses circulating in the population: sewage surveillance in Guangdong, China (2013-2018)

Noroviruses (NoVs) are the leading cause of acute gastroenteritis outbreaks. The specific geographical distribution and expanding diversity of NoVs has posed a challenge to NoV surveillance and interventions. Here, we describe the long-term dynamic correlation between NoV distribution in sewage and in the local population by using high-throughput sequencing and operational taxonomic unit (OTU) analysis. The NoV viral loads in sewage were closely associated with the number of NoV outbreaks in the population. Compared with the viral distributions in outbreaks, the dominance of the newly emerged variants, such as GII.P17-GII.17 and GII.P16-GII.2, could be detected two months ahead in sewage. In addition, the dynamics of pre-epidemic variants, which were rarely detected from clinics, could be captured through sewage surveillance, thus improving our understanding of the viral origin and evolution. Our data highlight that the high-throughput environmental screening should become a critical part of the response to infectious diseases.