Abstract. Blood samples from 186 HBsAg-positive Saudis and 42 HBsAg-positive Philippine blood donors were tested for anti-delta using the radioimmunoassay technique. The high prevalence of anti-delta in Saudis with liver disease (32%) contrasted sharply with that in Saudis with illness other than liver disease (13%) and in apparently healthy Saudis (5·4%). Together with the high prevalence of anti-delta in Philippine blood donors (9·5%), these results suggest that foci of endemic delta infection other than Italy probably exist.
