Community burden and transmission of acute gastroenteritis caused by norovirus and rotavirus in the Netherlands (RotaFam): a prospective household-based cohort study. Issue 5 (May 2020) - Quee, Franke A
Summary: Background: Norovirus and rotavirus are the dominant pathogens causing acute gastroenteritis in children. To quantify their natural disease burden and transmission, we prospectively monitored households in an endemic setting in the Netherlands, a high-income country that does not have a rotavirus vaccination programme. Methods: We did a prospective, household survey-based cohort study in the Netherlands. Randomly selected households from the Dutch Population Register were invited to participate if they had at least three household members, including a child younger than 2 years. A member of each household was asked to record the gastrointestinal symptoms of all household members every day for 10 consecutie weeks using an interactive smartphone application. Real-time detection of acute gastroenteritis onset on the basis of entered symptoms activated requests for the case and one other household member to complete disease questionnaires and provide stool samples. Stool samples were analysed by real-time PCR for norovirus, rotavirus, adenovirus 40/41, and astrovirus. We calculated the per-pathogen proportion of households with at least one secondary acute gastroenteritis episode (epidemiologically but not microbiologically linked), the probability of a secondary episode in household members at risk (secondary attack rate), and the microbiologically confirmed symptomatic and asymptomatic transmission rates. Findings: During two seasons (January to March) in 2016 and 2017, 30 660 households were invited to participate, of which 604 households including 2298 individuals were enrolled. 697 acute gastroenteritis episodes were detected in 358 households, with samples obtained from 609 (87%) of 697 episodes. Norovirus (150 [25%] of 609 cases) and rotavirus (91 [15%] cases) were most frequently detected. Astrovirus was detected in 50 (8%) samples and adenovirus 40/41 in 24 (4%) samples. Overall disease severity was higher in patients with rotavirus-positive acute gastroenteritis than those with norovirus-positive acute gastroenteritis. Norovirus led to higher disease burden in adults than did rotavirus. Following an index case, a secondary acute gastroenteritis episode occurred in 34 (35%) of 96 households for norovirus and 26 (46%) of 56 households for rotavirus. Secondary attack rates were 15% (37 of 244 participants) for norovirus and 28% (33 of 120 participants) for rotavirus and asymptomatic transmission rates were 51% (52 of 102 household members) for norovirus and 22% (12 of 55 household members) for rotavirus. The microbiologically confirmed symptomatic transmission rate for norovirus was 10% (25 of 254 household members) and 18% for rotavirus (21 of 119 household members). Interpretation: In households with young family members in a setting without rotavirus vaccination, norovirus is the dominant acute gastroenteritis pathogen, but rotavirus is associated with more severe disease. There was substantial within-household transmission, both symptomatic and asymptomatic. The study provides key quantities on transmission, which can inform vaccine policy decisions and act as a baseline for impact evaluations in high-income settings. Funding: The Netherlands Organisation for Health Research and Development (grant 91616158 ).