Low prevalence of delta hepatitis virus infection among blacks in Natal.
The prevalence of delta hepatitis virus (DHV) infection among hepatitis B surface antigen (HBsAg)-positive black subjects in Natal was determined. A total of 172 subjects was tested for the presence of antibodies to DHV; all were HBsAg-positive. They comprised three groups: 51 urban children identified in a community-based seroprevalence survey, 81 subjects identified during a family study, and 40 institutionalised children. None of the 172 subjects was positive for antibodies to DHV. Based on calculations using a binomial distribution of infection, there was a 95% probability that the prevalence of DHV infection was below 30/100,000 HBsAg-positive persons. While DHV infection was found to be rare among blacks in Natal, the risk of delta hepatitis becoming widespread is ever-present, since the high incidence of hepatitis B virus infection in black children provides ample opportunity for the concomitant spread of DHV.