Excretion of faecal viruses during the first year of life including attendance at a day nursery in Lisbon, Portugal.

In an attempt to determine the frequency of virus infections of the gastrointestinal tract, the duration of virus shedding in faeces and its relation to outbreaks of illness of any kind, faecal samples were collected from children attending a day nursery at a Lisbon institution. In this study, ten children were surveyed from their enrollment at the nursery, weekly specimens of faeces being collected over a period of 1 year. A total of 459 samples were obtained. In addition four of these children were also followed-up from their first week of life to their enrollment at the nursery, 79 samples being collected during this period. Viruses were detected in a high percentage (44.4%) of these stools, including strains of oral vaccine polioviruses together with viruses isolated in routine cell cultures and by electron microscopy (EM). These viruses were detected in both healthy and ill babies. The possible association between viruses isolated in cell cultures or detected by EM and illness was examined and the results show that the asymptomatic excretion of viruses is frequent, particularly in children within this age group.