HBsAg and HBV infection showed a higher prevalence in males before 55 years (Fig. 3). In total,
a cohort of 291 susceptibles was included to evaluate the HBV incidence: 75 in Dhiba (hyperendemic region) and 216 in Rogba (hypo-endemic region). At baseline FDA-approved Drug Library screening in 1996, they were seronegative for all markers and they were retested for HBV infection markers 3 years later. They did not receive any HBV vaccine between the 2 tests. Out of the total sample of the cohort, 15 in Dhiba and 6 in Rogba seroconverted corresponding to a cumulative incidence during 3 years of 20.0% CI95% [10.95–29.05%] and 2.8% CI95% [0.60–5.00%] in Dhiba and Rogba, respectively, leading to a mean annual incidence of infection of 6.67% CI95% [3.65–9.70%] and 0.93% CI95% [0.20–1.67%] in these two villages (p < 10−3). The first part of the analysis is related to the study of environmental, demographic
and behavioural risk factors at the individual level. Bivariate analysis revealed that Libraries education level, past history of scarification, needle practices in the Primary Care Centre (PCC), gender, existence of sanitation in the house, and family scarification practices were significantly associated with HBV infection and chronic carriage find more (Table 2). By multivariate analysis, family scarification practices, needle practices in the PCC and gender were significantly associated with anti-Hbc positivity (AOR equal to 2.15 CI95% [1.85–2.49], 1.64 CI95% [1.36–1.97] and 1.26 CI95% [1.12–1.42], respectively). The same risk factors were found for HBsAg positivity (AOR equal to 2.36 CI95% [1.60–3.00],
1.85 CI95% [1.24–2.77] and 1.53 CI95% [1.23–1.90], respectively) and chronic carriage (AOR equal to 2.85 CI95% [2.10–3.86], 2.37 CI95% [1.33–4.19] and 1.37 CI95% [1.02–1.83], Ketanserin respectively). Lack of sewage in the house was found to be protective against anti-HBc (AOR equal to 0.49 CI95% [0.37–0.65]), and HBsAg positivity (AOR equal to 0.08 CI95% [0.02–0.31]). No significant association between HBV subgroups and household size was noted (Table 3). The second part of the analysis attempted to assess the importance of transmission within the family as a risk factor to acquire infection for the individual. We concentrated on the study of non-sexual close contact risks. Therefore, we evaluated the risk of HBV infection of the individual due to: (i) HBV chronic carrier mother, (ii) HBV chronic carrier brother/sisters(s), and (iii) and HBV chronic carrier father. Individuals having a carrier mother are about three times more likely to be anti-HBc positive (AOR = 2.97 CI95% [1.86–4.75]), 10 times more likely to be HBsAg positive (AOR = 10.64 CI95% [6.23–17.82]) and six times more likely to be chronic carriers (AOR = 5.65 CI95% [3.09–10.33]). Those having HBV chronic carrier brother(s) or sister(s) are at high risk of HBV infection (AOR equal to 11.60 [8.35–16.12] for anti-HBc and 13.61 CI95% [8.78–21.07] for HBsAg) and chronic carriage (AOR = 24.73 CI95% [13.56–45.12]).