Objective To understand the epidemiological characteristics of the outbreak of norovirus-caused infectious diarrhea in an elderly tour group in Jinzhai, Anhui province, in 2023, analyze the risk factors of the outbreak, and provide evidence for the investigation and control infectious diarrhea outbreaks in the future.
Methods Epidemiological investigation and case-control study were carried out according to the case definition. Samples such as vomitus and anal swabs, food and drinking water were collected for fluorescent PCR qualitative detection to identify the pathogen.
Results A total of 31 suspected cases were reported in this outbreak, with close onset times and similar clinical manifestations of abdominal pain and diarrhea. The samples collected, including 10 biological samples, 1 water sample and 3 environmental smear samples, were tested positive for norovirus nucleic acid. All the cases had lunch in a hotel canteen on 3 August 2023, and the coleslaw contaminated by self-supplied water might be the source of the infection of norovirus.
Conclusion The outbreak of infectious diarrhea was caused by norovirus due to a common dietary exposure to contaminated food by water.