Investigation of a hepatitis A outbreak in a primary school by sequential saliva sampling

An outbreak of hepatitis A occurred in a primary school (children aged 4-11 years), starting in the Autumn of 1990 and terminating some 5 months later after some spread into the local community.

The objectives were to monitor the spread of the virus within the primary school over time, to document infection in asymptomatic individuals and the efficacy of using saliva for HAV antibody detection in young children as an acceptable screening method by using the Salivette method and ordinary cotton tipped swabs.

Serial saliva samples were taken over a period of months and anti-HAV IgM and IgG antibodies measured by radioimmunoassay.

Twenty-seven children in the school and nine individuals from the surrounding community acquired hepatitis A. Twenty-one (78%) of the 27 children were symptomatic, as were all the affected adults. The cotton-tipped swabs were found to be as effective a method as Salivette at diagnosing infection in those in whom the methods were compared.

Despite many reports stating that children are more likely to be asymptomatic with HAV infection we found the majority to report significant symptoms. Young children do not easily accept serum sampling as a method for diagnosis or epidemiological studies, and we show that saliva sampling is an effective and acceptable diagnostic method.