[Epidemiological characteristics of enteritis due to norovirus in Guizhou Province, 2016-2023]

Objective: To understand the incidence and epidemiological characteristics of enteritis due to norovirus infection in Guizhou Province from 2016 to 2023, and provide reference for the prevention and control of enteritis caused by norovirus. Methods: The data were from National Notifiable Infectious Disease Reporting System of China Information System for Disease Control and Prevention. To collect the data of other infectious diarrhea cards in Guizhou from 2016 to 2023, which were annotated as enteritis due to norovirus and food-borne disease surveillance sentinel report in Guizhou, which were positive for norovirus detection. The data of cluster/outbreaks were from the Public Health Emergency Event Surveillance System and the field investigation reports of CDC at all levels. Descriptive epidemiological method was used to describe the characteristics of its three-dimension distribution, epidemic situation and pathogen spectrum. R 4.2.2 software was used for statistical analysis. Results: A total of 2 340 cases of enteritis due to norovirus were reported in Guizhou Province during this period, with an average annual reported incidence of 0.79/100 000, and the incidence showed an upward trend (trend χ²=1 723.80, P<0.001). The high incidence season is from October to March (winter and spring). The male to female ratio of the cases was 1.39∶1 (1 362∶978). A total 1 382 cases occurred in age group under 5 years old (59.06%) and 1 249 cases occurred in children living scatteredly (53.38%). The average annual reported incidence in 6 prefectures (muniipality)(1.15/100 000 in Qiandongnan Miao and Dong Autonomous Prefecture, 1.08/100 000 in Guiyang, 1.07/100 000 in Liupanshui, 1.06/100 000 in Qianxinan Buyi and Miao Autonomous Prefecture, 0.91/100 000 in Qiannan Buyi and Miao Autonomous Prefecture and 0.89/100 000 in Tongren) in Guizhou Province was higher than provincial level, and the affected areas gradually expanded from southeastern counties (districts) to western and northern counties (districts). The average annual reported incidence rate was higher in urban area (1.12/100 000) than in rural area (0.39/100 000). A total of 31 cluster/outbreaks of enteritis due to norovirus were reported, in which 83.87% (26/31) occurred in child care settings, primary and secondary schools, in which 74.19% (23/31) were caused by human-to-human transmission. In the 2 340 cases, 2 147 were laboratory diagnosed (91.75%), and 193 were clinically diagnosed (8.25%). In the laboratory diagnosed cases, 2 026 (94.36%) were caused by single norovirus infection and 121 (5.64 %) were caused by mixed infection. Conclusions: On the whole, the incidence of enteritis due to norovirus in Guizhou Province was on the rise from 2016 to 2023, and winter and spring were the high incidence seasons. Effective prevention and control measures should be taken for key populations, key regions and key places, and multi-channel and multi-pathogen surveillance and health education should be strengthened.