Astrovirus; Contactos domésticos; BroteAstrovirus; Contactes domèstics; BrotAstrovirus; Household contacts; OutbreakWe investigated an outbreak of acute gastroenteritis due to human astrovirus in a daycare center, describing the transmission mechanism, the most affected age groups, conditioning factors and the extent of the outbreak among household contacts of the daycare center attenders. Data were collected from persons exposed at the daycare center and their home contacts. Fecal samples from affected and non-affected daycare center attenders were analyzed for viruses causing acute gastroenteritis by RT-PCR. The percentage of households affected and the attack rates (AR) were calculated. The attack rates were compared using the rate ratio (RR) with 95% confidence intervals. Information was obtained from 245 people (76 attenders and 169 contacts) of whom 49 were clinical cases. Five HAstV-4, two HAstV-8 and three non-typable HAstV cases were identified (six from clinical cases and four from asymptomatic infected people). The global AR was 20% (41.2% in children aged < 2 years). Data were obtained from 67 households: 20 households of affected attenders and 47 of non-affected attendees. Household contacts of affected attenders had a higher AR (74.3%) than that of non-affected attendees (2.4%). We found asymptomatic infections amongst daycare attendees. The transmission of HAstV during the outbreak was not limited to the daycare center but extended to household contacts of both affected and non-affected attenders.This study was funded by Instituto de Salud Carlos III through the project PI16/02005 (Co-funded by the European Regional Development Fund “Investing in your future”) and the Catalan Agency for the Management of Grants for University (AGAUR Grant Number 2017/SGR 1342)
