A SCHOOL OUTBREAK OF PARVOVIRUS B19 INFECTION INVESTIGATED USING SALIVARY ANTIBODY-ASSAYS

An outbreak of parvovirus B19 infection at a primary school was invest igated using saliva samples. Antibody capture immunoassays for salivar y B19 IgG and IgM were developed using a recombinant B19 antigen and m onoclonal antibody to B19 virus. Evaluation of the salivary IgG assay using paired serum and saliva samples from 43 staff at St Thomas' Hosp ital showed that it had a sensitivity of 100% and a specificity of 95% . Evaluation of the salivary B19 IgM assay using 87 paired blood and s aliva samples from a study of general practitioner rubella notificatio ns showed it had a sensitivity of 60% and a specificity of 98%, Using the salivary assay the level of B19 IgG within 2 weeks of the start of the outbreak ranged from 5-33% in children and 29% in staff. By detec ting salivary B19 IgM and/or B19 Ige seroconversions, attack rates of 8-50% in children in different classes and 47% in staff were observed. Household transmission was also studied and an attack rate of 45% was recorded in 11 susceptibles, After the outbreak, the level of B19 IgG in children with the highest attack rates was 60-70%, similar to that seen in adults in the UK, This study highlights the risk of B19 infec tion in an institutional setting and shows that saliva samples are a u seful alternative to blood.