Epidemiology of hepatitis B in Somalia: inference from a cross-sectional survey of serological markers

Hepatitis B markers were determined by radioimmunoassay in 383 adults from different areas of Somalia and in 135 pregnant females and 428 children from Mogadishu. The highest incidence of HBsAg among adults was among nomadic males (20/85; 23%). The frequencies were lower in males from the agricultural and coastal area, i.e. 16/93 (17%) and 14/98 (14%) respectively. The lowest frequency of HBsAg was among women from the coastal area (6/72; 8%). Among the pregnant women 14 were positive for HBsAg, none of whom had HBeAg. Low levels of positivity for HBsAg were found both among children under 4 years and among those between 4 and 13 years of age - 3/94 (3%) and 5/128 (4%) respectively. In the age group 15-19 years, 50% showed seroconversion from HBeAg to anti-HBe. 7 out of 41 HBsAg carriers of ages over 20 had HBeAg. Early seroconversion from HBeAg to anti-HBe and a low level of HBsAg positivity in children indicate that vertical transmission is not important in Somalia. The low frequency of HBsAg in Mogadishu children may have one of the following explanations: (i) the infection occurs during adolescence, (ii) Mogadishu is a low-prevalence area and the examined adults were not born in Mogadishu, or (iii) a change in hepatitis B epidemiology has taken place in the area during the last 2 decades and the relatively higher prevalence of HBsAg in adults might reflect higher rates of infection in their childhood.