Seroepidemiological study of genogroup I and II calicivirus infections in South and Southern Africa

Diarrhoea is associated with the daily death of between 180 and 200 childre n under the age of 5 years in South Africa. Until recently, many cases and outbreaks of diarrhoea were not associated with a known aetiologic agent. P revious studies using baculovirus-expressed Norwalk virus (NV) and Mexico v irus (MxV) capsid antigens have shown that human calicivirus infection is c ommon in South Africa. In this study, our surveillance was extended to diff erent populations, as well as to four other southern African countries: Nam ibia, Angola, Zimbabwe, and Mozambique. More than 1,700 specimens, some inv olved in previous cohort studies of infectious diseases, were enrolled in t he surveillance. The overall seroprevalence of antibody against NV was >90% for all cohorts except for Mozambican refugees that had 83.8% sere-positiv ity. The MxV antibody prevalence was higher than NV, with >95% positivity f or all cohorts, except for one in Namibia that had 81% exposure. This study is one of only a few reporting on the concurrent incidence of NV and MxV i nfections in a cohort study, and has determined that small round structured viruses are prevalent in the local populations of South and Southern Afric a. These agents may account for a number of previously unknown or unidentif ied causes of diarrhoeal illness, in both adults and children, in southern Africa. (C) 1999 Wiley-Liss, Inc.