Horizontal transmission of hepatitis B in a children's day-care centre: a preventable event.

Using molecular finger-printing, we provided evidence that, in a children's day-care centre, a known hepatitis B virus (HBV) hepatitis B e antigen (HBeAg) carrier transmitted HBV to another child (the index case). The chronic HBV carrier had an exudative skin lesion and a history of biting. We sought to identify other at-risk children and prevent further transmission. Blood samples were collected and tested serologically for HBV. Of the 90 other children, 78 (87 per cent) were tested and none had serological evidence of HBV infection; 73 (81 per cent) were of Caucasian background; 38 (49 per cent) had a history of HBV immunisation with serological confirmation. Therefore, 1 (2.4 per cent, 95 per cent confidence interval 1.0 to 12.8 per cent) of the 41 known susceptible contacts became infected. The risk of horizontal HBV transmission in a children's day-care centre is low but not negligible. Staff and children should be vaccinated when a child in a day-care centre is a known HBV carrier.