Prevalence, Clinical Features, and Genotypes of Norovirus-Associated Diarrhea in Wuxi, China, 2013–2020

Norovirus (NoV) is a common pathogen that can cause infectious diarrhea. This study aimed to determine the prevalence, clinical features, and genotypes of NoV-associated diarrhea in Wuxi, China. A total of 4,416 stool samples were collected from patients with diarrhea at enteric disease clinics of sentinel hospitals in Wuxi from February 1, 2013 to December 31, 2020. Univariate and Akaike information criterion stepwise logistic regression were used to identify differences as integrated within a clinical setting (NoV positive [+] versus NoV negative [-], NoV+ versus rotavirus [RV]+, NoV+ versus bacteria+, genogroup [G] I and GII genotypes). Norovirus was detected in 9.85% of stool samples, which was greater than other tested pathogens. Excluding coinfection of NoV and other viruses or bacteria, patients infected with NoV had a lower chance of acquiring the virus in summer (P < 0.001; odds ratio [OR], 0.257; 95% CI, 0.189-0.36) when compared with patients without NoV. Patients with diarrhea infected with NoV featured nausea and vomiting (P < 0.001; OR, 2.297, 95% CI, 1.85-2.86) and loose stools (P = 0.006; OR, 2.247; 95% CI, 1.30-4.10), but less abdominal cramping (P = 0.001; OR, 0.676; 95% CI, 0.54-0.84). Patients infected with RV (P < 0.001; OR, 0.413; 95% CI, 0.25-0.68) or bacteria (P < 0.001; OR, 0.422; 95% CI, 0.26-0.67) were more vulnerable to fever than those infected with NoV. A total of 379 GII strains were detected concomitant with 48 GI strains, and there was a seasonal difference between the GI and GII genotypes. Strengthening pathogen detection for infectious diarrhea was helpful for understanding the epidemiological characteristics of infections with NoV and, potentially, for preventing disease outbreaks.