Investigation of a Norovirus GII outbreak in a primary school in Portugal,2023

Abstract Background The onset of acute gastroenteritis cases among students in a primary school class on September 19, 2023, prompted an immediate response from the local Public Health unit. A collaborative effort was initiated to investigate and contain the outbreak. Methods Epidemiological questionnaires were distributed to 166 students and 8 staff members, defining cases as individuals exhibiting symptoms including diarrhoea, vomiting, or nausea between September 19th and September 24th, 2023. Additionally, stool samples were collected from three individuals. Results Out of 166 students and 8 staff members, 39 individuals met the case definition, resulting in attack rates of 22% (37/166) and 25% (2/8) among students and staff, respectively. Laboratory analysis confirmed two cases of Norovirus GII among the tested specimens, with five students requiring medical attention. Conclusions Our investigation underscores the significance of continuous epidemiological surveillance and swift implementation of infection control measures in school settings. The detection of Norovirus transmission emphasizes the necessity for rigorous adherence to infection control best practices. Our findings advocate for sustained technical support from public health authorities to prevent and manage similar outbreaks effectively. Key messages • Study on Norovirus outbreak in a primary school highlights the imperative of infection control measures, emphasizing the importance of ongoing support from public health authorities. • The Norovirus outbreak investigation underscores the vital role of surveillance and swift response in containing infectious diseases within educational settings safeguarding all.