Polymerase chain reaction in the detection of an ‘outbreak’ of asymptomatic viral infections in a community birth cohort in south India

Abstract

SUMMARYAsymptomatic enteric infections are important where sequelae or protection from subsequent illness is an outcome measure. The use of reverse transcription–polymerase chain reaction (RT–PCR) to identify asymptomatic enteric infections in a birth cohort followed for rotaviral infections in a south Indian urban slum is reported. Of 1191 non-diarrhoeal samples from 371 children collected in May–June 2003, 22 (1·9%) were positive by ELISA. A total of 147 (40·6%) of 362 samples tested by VP6 RT–PCR were positive. In those samples that could be typed, a high diversity of G types including G1, G2, G4, G8, G9 and G10, and a high proportion (34·4%) of mixed infections were detected. Noroviruses were identified in 6/28 (21·4%) samples tested. The identification of infections undetectable by conventional techniques indicates the importance of the use of sensitive diagnostic techniques in research studies. Asymptomatically infected children may also act as a source of infection for other susceptible hosts.