INTRODUCTION: Norovirus infection, a major cause of acute viral gastroenteritis, is commonly reported during the winter season. Norovirus invades the upper intestinal tract, causing inflammation. In severe cases, endoscopic findings and complications, including duodenal perforation, have been reported. However endoscopic findings in patients with asymptomatic infections have rarely been reported. Therefore, this study aimed to investigate the upper endoscopic findings of patients with asymptomatic norovirus infection. METHODS: Healthy adults (aged ≥18 years) who participated in voluntary health examinations between February 2017 and January 2018 were recruited twice a week. Only the individuals who had undergone esophagogastroduodenoscopy (EGD) were included. The primary outcome measure was the presence of any gross findings of EGD. RESULTS: The norovirus genogroup I (GI)-positive group had more duodenal scarring than the norovirus negative group (16.3 % vs 5.9 %, respectively). After adjustment for age category, sex, and alcohol consumption status, duodenal ulcer scarring exhibited a significant association with GI-positive status (adjusted odds ratio: 3.11
95 % confidence interval: 1.42-6.82
p = 0.005, Bonferroni-corrected, p = 0.015). CONCLUSIONS: Healthy adults with asymptomatic norovirus (GI-positive) infection showed predominantly more duodenal ulcer scarring than the norovirus-negative group on EGD.