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Systematic Review of Norovirus Outbreaks in China: Epidemiological
Characteristics and Transmission Variations.
Abstract
Norovirus represents one of the primary pathogens responsible for
gastroenteritis on a global scale, exerting a significant impact on
foodborne illnesses. In recent years, China has emerged as a region of
particular significance with regard to the occurrence of norovirus
outbreaks. This study presents a systematic review of norovirus
outbreaks in China, offering a comprehensive overview and analysis of
norovirus epidemics. A total of 680 articles reporting 798 outbreaks
were included from four databases (CNKI, CHINA Wanfang, Web of Science,
and PubMed). Firstly, an overall historical review of norovirus
outbreaks in China over the past two decades is conducted, detailing the
fluctuations in reported outbreak numbers and cases influenced by
different global strains and the COVID-19 pandemic. A comparison of the
changes in the scale of outbreaks (the number of cases, attack rate,
duration, and reporting time), significant differences are found in the
number of cases and duration of outbreaks (P<0.001).
Furthermore, the epidemiological characteristics are examined from five
perspectives: region, seasonality, setting, transmission, and genogroup.
It was found that high-incidence regions are concentrated in the
southern and eastern regions of China, with outbreaks primarily
occurring in winter. Schools are identified as key outbreak setting, and
foodborne transmission is the main mode of transmission. The GII
genogroup is particularly prevalent, with GII.2 and GII.4 being the most
dominant. Based on above findings, the article also cross-analyzes
seasonal variations in different provinces and transmission modes under
different settings and genogroups. In most settings, foodborne
transmission is the primary mode, whereas person-to-person and
waterborne transmission prevail in settings like schools and
communities, respectively. The GII genogroup primarily spread through
person-to-person contact, food, and aerosols caused by vomiting. In
contrast, the GI genogroup and I/II mixed genogroups mainly spread
through water and food.