Hepatitis B prevalence and risk factors for HBsAg carriage amongst Somali households in Liverpool.

The prevalence of hepatitis B core antibody (anti-HBc) and surface antigen (HBsAg) in the Somali population in Liverpool is described and groups who may benefit from vaccination are identified. A cross-sectional descriptive study was undertaken. A total of 439 subjects, aged between 10 months and 80 years, from 151 households, were screened for anti-HBc and HBsAg. One hundred ninety-four (44.2%) were children aged less than 15 years. Three hundred and nine (69%) of enrolled subjects were born in Somalia, 122 (27.2%) were born in the UK and 8 were born elsewhere. Of the study population, 5.7% were carriers of HBsAg, with the highest prevalence in adults aged 20 to 44 years (9.4%). A history of circumcision (RR 95% CI; 1.2, 1.1-1.5) was the most significant risk factor for HBsAg carriage, but was not significant on multivariate analysis. Prevalence of anti-HBc was 27.5%, and increased with age over the first four decades. Univariate analysis showed that a history of living in a refugee camp (RR 95% CI; 3.1, 1.7-5.7), receiving an injection in Somalia (2.1, 1.7-2.5), a history of circumcision or other surgical procedure in Somalia (1.4, 1.3-1.6) and being born in Somalia (1.3, 1.2-1.4) were significant risk factors for anti-HBc positivity. On multivariate analysis, only circumcision (OR 95% CI; 4.3, 1.8-10.3) and receiving an injection in Somalia (2.5, 1.5-4.4) remained significant. Seven of 80 (8.7%) children born in the UK and aged five years or less had evidence of exposure to hepatitis B, of whom only one had a close family member identified to be HBsAg seropositive. Previous infection with hepatitis B is common in this population. Horizontal transmission may be continuing at an early age within the UK, suggesting a population of at risk individuals who would benefit from surveillance and immunisation. Community circumcision is a risk factor for hepatitis B transmission and best practice should be followed when this procedure is undertaken.