Transmission of hepatitis B virus infection in Ethiopia with emphasis on the importance of vertical transmission.
This two-year controlled study was conducted to define the mode of transmission of hepatitis B infection in Ethiopia. Twenty-five of 500 (5%) expectant mothers were identified as HbsAg positive (Group A). A control group of 29 mothers negative for HBsAg (Group B) was randomly selected. These 54 mothers and their families (husbands, infants and the infants' older siblings) were followed for two years with determinations of serological markers of ongoing or past hepatitis B virus infection at 6, 12 and 24 months. Social and clinical data as well as possible factors contributing to the spread of HBV (ie tattoos, circumcision, etc.) were compiled from questionnaires. Twenty-one of the 25 (84%) HBsAg positive mothers had anti-HBe and none had HBeAg. One case of vertical hepatitis B virus transmission was seen while horizontal transmission during the study period occurred in two infants and in two older siblings. Potential risk factors for non-perinatal transmission were highly prevalent in both groups and may represent the main route of transmitting the infection, while, as shown in the present study, the vertical transmission of HBV infection only plays a minor role in the maintenance of the high infection rate in Ethiopia. Vaccinating all babies soon after birth would, therefore, be an effective means of eradicating or reducing the hepatitis B virus infection and its sequelae.