Molecular epidemiology of norovirus infection in hospitalized diarrheal children aged <5 years in Urumqi, 2017–2019

  Objective  To understand the molecular epidemiological characteristics of norovirus infection in hospitalized diarrheal children under 5 years old in Urumqi, Xinjiang Uygur Autonomous Region, from 2017 to 2019.

  Methods  Stool samples and epidemiological data were collected from 976 sick children under 5 years old hospitalized in Urumqi Hospital due to acute diarrhea from 2017 to 2019, and Real-time fluorescence quantitative-polymerase chain reaction was performed for norovirus detection. The positive samples were amplified by reverse transcription-polymerase chain reaction and sequenced. The epidemiological characteristics were analyzed combined with clinical data.

  Results  The detection rate of norovirus nucleic acid was 25.20% (246/976), the differences in positive rate among different years were significant (χ²＝40.724, P<0.0001). The detection rate of norovirus nucleic acid was highest in 0.5–1 years old group (30.61%, 101/330), and there were no significant differences among different age groups. The sequences in the ORF1/ORF2 overlap were obtained from 110 strains, including 7 genotypes. GⅡ. 4 Sydney ［P31］ was predominant, accounting for 59.09% (65/110), followed by GⅡ. 3 ［P12］ (18.18%, 20/110) and GⅡ. 2 ［P16］ (17.27%, 19/110), and other genotypes included GⅡ. 6 ［P7］ (2.72%, 3/110), GⅡ. 4 Sydney ［P16］ (0.91%, 1/110), GⅡ. 1 ［P16］ (0.91%, 1/110) and GⅠ. 4 ［P4］(0.91%, 1/110). GⅡ. 2 ［P16］ emerged in the second quarter of 2017 and became predominant in the third quarter of 2019.

  Conclusion  Norovirus is one of the main pathogens causing diarrhea in children under 5 years old in Xinjiang. GⅡ. 4 Sydney ［P31］, GⅡ. 3 ［P12］ and GⅡ. 2 ［P16］ are the main genotypes of norovirus in Xinjiang.