Investigation of noruvirus infection status in diarrhea cases in sentinel hospitals in Tianjin, 2015–2016

Objective To understand the epidemiologic characteristics of norovirus infection in sporadic diarrhea cases in Tianjin during 2015–2016.

Methods The epidemiological information of sporadic diarrhea cases were collected from five sentinel hospitals in Tianjin from January 2015 to December 2016. The stool samples were collected for norovirus nucleic acids detection by using real-time reverse transcription-PCR (real-time RT-PCR), and genotyping was performed for the detected strains.

Results A total of 1 249 stool samples were collected from the diarrhea cases, the positive rate of norovirus was 14.41% (180/1 249); The highest detection rate was found in young children aged ＜1 year, with a detection rate of 26.07% (85/326); The differences in detection rate among different age groups had significance, (P＜0.01). The detection rate of noroviruses was significantly higher in the first and fourth quarters than in the second and third quarters. The detection rates in Binhai new district, urban area and rural area were 30%, 16.62% and 11.89%, respectively. GⅡ was the predominant genotype of norovirus detected in the diarrhea cases. The infections with norovirus GⅡ accounted for 86.05%, the infection with norovirus GⅠ accounted for 11.05%, and co-infection with noroviruses GⅠ and GⅡ accounted for 2.91%. The infection rate of norovirus GⅠwas highest in age group 6–45 years (33.33%). The infections with norovirus CⅠ mainly occurred during April-September.

Conclusion The infection rate of norovirus in diarrhea cases in Tianjin sentinel hospital was high. The incidence in winter and spring was high. Binhai new district was an area with high incidence, infants and young children were group with high incidence. GⅡ was the predominant genotype. The incidence of infection with norovirus GⅠ was relatively high in young and middle-aged groups. It is necessary to conduct the prevention and control of norovirus infection according to the epidemic characteristics, and active surveillance should be conducted in populations at high risk.