RESUMEN
BACKGROUND: To know and compare the prevalence of hepatitis B (HB) in two marginal populations (ciganes and gypsies) presumably pertaining to the same ethnic group and considered to have high risk for the disease. METHODS: Serologic markers were determined in 245 ciganes (65% of the total of the cigane population) and in 127 gypsies (45% of the total gypsy population). One hundred three individuals randomly chosen from the neighborhood were studied as a control group. RESULTS: HbsAg was negative in the gypsies and positive in 0.9% of the controls and in 27% of the ciganes (p < 0.001). HbeAg was positive in 15% of the ciganes and negative in the other two groups (p < 0.001). Antibodies were found in 10% of the controls, 12% of the gypsies and in 72% of the ciganes (p < 0.001). In gypsies it was found that 29% were infected from adolescence versus 13% of the control population (p < 0.001). High intrafamily horizontal transmission in infancy was found in the ciganes in addition to vertical transmission. CONCLUSIONS: The different habits and more precarious life style of the ciganes with respect to the gypsies may be the cause for the hyperendemia of hepatitis B in the former.