Seroepidemiology of hepatitis B virus infection in 2 million men aged 21-49 years in rural China: a population-based, cross-sectional study

Background Hepatitis B virus (HBV) infection is highly endemic (7-8% prevalence) in rural China, causing high mortality and societal burden. Data from men of reproductive age is scarce and last reported in 2006. We assessed the seroepidemiology of men in rural China, aiming to provide updated baseline data for the prevalence of HBV infection. Methods We established prevalence of HBV infection from data gathered through a nationwide population-based study of Chinese rural men aged 21-49 years. Data were obtained from a physical check-up programme for couples of reproductive age, the National Free Preconception Health Examination Project, that covered 31 provinces from 2010-12. We tested serological samples with ELISA and categorised participants' HBV status based on presence of HBsAg, anti-HBV core antibody (anti-HBc), and anti-HBV surface antibody (anti-HBs). Findings 2 030 083 men were recruited into the database from Jan 1, 2010, to Dec 31, 2012, and 1 966 013 men provided serum samples for analysis. 124 274 men (6%) tested positive for HBsAg, 178 559 (9%) tested positive for anti-HBc, and 583 923 (30%) tested positive for anti-HBs. Isolated anti-HBs (an indicator of vaccine-mediated immunity) were present in 527 566 men (27%). And 1 234 127 men (63%) were negative for all HBV makers (susceptible population). HBsAg prevalence was higher in men aged 25-39 years (6.35-6.47%) than in other age groups (5.54-5.78%; p<0.0001). HBV markers were all more prevalent in the eastern region of China than in the central or western regions (all p<0.0001). 32 326 (26%) of 124 274 HBsAg-positive men tested positive for HBeAg (suggesting high infectiousness); this decreased with increasing age (p<0.0001). Interpretation HBV prevalence in men in rural China has changed from highly endemic into intermediate endemic in the past two decades. However, the absolute number of HBV-infected men and the susceptible population is still very large.