Detection of Norwalk and Mexico virus, two human calciviruses in stools ofChilean children

Background: Human calciviruses (HuCVs) cause diarrhea outbreaks associated with consumption of contaminated food and water. Seroepidemiological studie s in developing countries, suggest that HuCVs can cause acute gastroenterit is in children. Aim: To study the presence of Norwalk (NV) and Mexico (MX) virus, two HuCVs, in stools of Chilean children from different settings. Su bjects and methods: ELISA tests for NV and MX were performed in 677 stool s amples for children aged 0 to 132 years old, with acute diarrhea occurring in day care centers or consulting in outpatient clinics or emergency rooms. We also studied eight samples from children involved in a diarrhea outbrea k that occurred in a rural community in 1992. A subset of samples was teste d with polymerase chain reactions using different primers. Results: Only on e sample from a child with acute diarrhea occurring in a day care center wa s positive for HuCV by polymerase chain reaction. Three samples from the ou tbreak were positive by the latter method and by ELISA. The HuCV obtained f rom the day care center was genetically different from other known HuCV. Co nclusions: Despite the high seroprevalence, NV and MX viruses were detected in a very low proportion of Chilean children stools.