A molecular epidemiological study of pediatric norovirus gastroenteritis, 2017-2019

To study the molecular epidemiological characteristics of norovirus in children with acute gastroenteritis from 2017 to 2019.

A retrospective analysis was performed on the medical data of children with acute gastroenteritis who were admitted to Children's Hospital of Chongqing Medical University from January 2017 to December 2019. A total of 1 458 stool samples were collected from the children, and viral RNA was extracted. Reverse transcription polymerase chain reaction was used for gene amplification, sequencing, and genotype identification of the VP1 region of capsid protein in norovirus.

Among the 1 458 stool samples, 158 (10.8%) were positive for norovirus. There was no significant difference in the positive detection rate of norovirus between different years (P>0.05). Boys had a norovirus detection rate of 12.2% (105/860), which was significantly higher than that in girls (8.9%, 53/598) (P=0.043). The children aged 12 to <18 months had the highest norovirus detection rate (16.9%, 51/301). August, September, and October were the epidemic peak season. A total of 23 norovirus-positive samples were also positive for rotavirus. The norovirus detected were mainly GII type (97.5%, 154/158), and only 4 cases were GI type (2.5%, 4/158). The sequencing of the VP1 region of capsid protein in the positive samples showed that GII.4 (69.6%, 110/158) was the dominant genotype, among which 99 (62.7%, 99/158) were GII.4 Sydney 2012, followed by GII.3 (15.2%, 24/158), GII.2 (10.1%, 16/158), GII.6 (1.9%, 3/158), and GII.17 (0.6%, 1/158). GI.3 (1.3%, 2/158), GI.2 (0.6%, 1/158), and GI.5 (0.6%, 1/158) were rarely detected.

Norovirus GII.4 Sydney 2012 was the major epidemic strain in the children with norovirus gastroenteritis from 2017 to 2019. Although norovirus infection can exist throughout the year, August to October is the peak period. During this period, norovirus surveillance and key population protection are strengthened to help prevent and control norovirus diarrhea.