Molecular epidemiology of GI and GII noroviruses in sewage: 1-year surveillance in eastern China

Abstract

Aims: To determine the concentration and molecular epidemiology of GI and GII noroviruses in sewage in China.

Methods and results: Twenty-three raw sewage samples were collected in the cities of Jinan and Linyi, eastern China in 2014. GI and GII noroviruses were positive in all samples after TaqMan-based quantitative PCR. The mean concentrations of GI and GII noroviruses were 4·52 × 10(4) and 7·88 × 10(4) genome copies per litre respectively. After reverse transcription-PCR, cloning and sequencing, 16 genotypes were identified. GI.6 (69·6%), GI.2 (65·2%), GII.13 (65·2%), GII.6 (60·9%) and GII.17 (60·9%) were the most common GI and GII genotypes. A recombination event was observed in two GI.6 sequences. GII.4 sequences belonged to Sydney 2012 and Den Haag 2006b variant. Interestingly, the novel GII.17 Kawasaki308 variant was detected.

Conclusions: These results reveal that multiple norovirus genotypes cocirculated in the local population. The risk of acute gastroenteritis outbreak is high in the two cities due to the detection of GII.17 Kawasaki308 variant and the high concentration of norovirus in raw sewage.

Significance and impact of the study: This study demonstrates sewage surveillance can be a useful approach to monitor norovirus circulating in the population.

Keywords: China; molecular epidemiology; norovirus; quantification; sewage.