Salivary sampling for hepatitis B surface antigen carriage: a sensitive technique suitable for epidemiological studies.

Vertical transmission from mothers to infants of hepatitis B infection result in a high incidence of carriage in children with long-term consequences, and is the focus of current immunization strategies. The use of saliva for hepatitis B surface antigen (HBsAg) screening in a country with an intermediate to high prevalence of chronic carriage was investigated. We recruited 88 Thai women with known HBsAg status (44 positive, 44 negative) who were attending an antenatal clinic. The collection of saliva was acceptable to all patients. Aspects of technique regarding collection and handling in a tropical setting are discussed. Comparing the detection of HBsAg in saliva to serum using a commercially available serological test kit without modification, the sensitivity was 92.0% (95% CI 84.8-99.5) and the specificity was 86.8% (95% CI 76.0-97.6). Population acceptability and safety advantages along with a high sensitivity strongly support the use of salivary sampling for epidemiological surveillance of hepatitis B virus.