PREVALENCE OF ANTIBODIES TO NORWALK VIRUS AMONG AMERINDIANS IN ISOLATED AMAZONIAN COMMUNITIES

The seroepidemiology of Norwalk virus infections was examined among Am erindians belonging to eight relatively isolated communities in the Am azon region by means of a new enzyme immunoassay using recombinant Nor walk virus antigen. The seroprevalence of antibodies to Norwalk virus ranged from 39% in the Maiogong to 100% in the Kubenkrankrein. The dis tribution of antibody levels varied greatly among groups; five of the eight communities had an antibody prevalence greater than 90% with man y high values (> 100 units), while three had both a low seroprevalence and a preponderance of low values (< 100 units). While few children l ess than 5 years of age were sampled, no significant differences in an tibody prevalence were noted among age groups, and the prevalence of a ntibody among children 5-10 years of age approached that of the older age groups. The low prevalence of titers of antibodies to Norwalk viru s in several tribes living in these isolated Indian communities sugges ts that Norwalk virus may have been only recently introduced.