Quantitative aspects of rotavirus excretion in childhood diarrhoea.

The amount of rotavirus (antigen) in diarrhoeal stools was determined from serially diluted faecal specimens using a solid phase radioimmunoassay (RIA) method. The acute stage RIA titres for rotavirus antigen ranged from 1:200 to 1:200 000 with a mean titre of 1:2 936 in a group of 16 infants with age range 2 to 14 months and 1:4 703 in a group of 12 children aged 25 to 94 months. In the younger age-group the diarrhoea lasted longer (mean 7.8 days) than in the older children (mean 5.4 days) despite the fact that the quantity of rotavirus was similar. In most of the younger infants there was either no demonstrable rotavirus present at the time of cessation of diarrhoea, or the amount of virus was on the decrease. In contrast, among the older children there were cases with a high titre of rotavirus in the stools a few days after the diarrhoea had ceased. These children were considered as potential spreaders of rotavirus infection in the community. However, none of the long-term follow-up stool specimens, collected 28 to 47 days after the onset of diarrhoea, were positive for rotavirus RIA.