[Seroepidemiologic survey of the spread of rotavirus infection in a Milan population].

The increasing evidence of involvement of Rotaviruses in the etiology of viral gastroenteritis prompted us to carry on a seroepidemiological survey on the population of Milan. The aim was to get informations on the extension of the circulation of these agents in our population. Utilising a commercial antigen prepared with the "Oslo" bovine strain, c.f.a. were titrated in sera from 575 healthy subjects (age 0 to > 60 years). Of them 232 were children under 4 years of age homogeneously distributed into 6 age classes: at birth, 1 day to 3 months, 4-6 months, 7-12 months, 13-24 months, 2-4 years. Rotavirus infection appears very common. About 80% of the subjects over 10 years have c.f.a. As it is shown by the sharp increase of antibody acquisition after an initial drop in the first 6 months (82% positive at birth and 41% between 4-6 months), the infection seems to occur very early in life, as much as the plateau is reached under 10 years of age. Moreover consistent antibody titers (greater than or equal to 1:32), which could indicate recent infection, first appear in babies 4 to 12 months of age. Such titres are absent in the adults and could be found again in people over 50. Positivity was significantly higher in females than in males (0.01 < P < 0.025). Transplacental c.f.a. passage was studied in paired sera of 37 women at delivery and in cord blood sera of their babies; 28 matched pairs of sera had coincidental titres, but there were additional three cord blood specimens with c.f.a. from newborns whose mothers were negative.