A SEROEPIDEMIOLOGIC CROSS-SECTIONAL STUDY OF HEPATITIS-B VIRUS IN ZIMBABWE

Objective. To estimate the prevalence of hepatitis B viral markers. De sign. A sero-epidemiological community-based cross-sectional study. Se tting. All nine provinces of Zimbabwe. Participants. From April 1989 t o December 1991 serum samples were collected from 1 461 males and 1 93 3 females in the age group 10 - 61 years, the majority in the younger age groups. Main outcome measures. Sera were tested for hepatitis B su rface antigen (HBsAg), hepatitis B e antigen (HBeAg), antibody to HBs- Ag (anti-HBs), antibody to hepatitis B core antigen (anti-HBc) and ant ibody to hepatitis B e antigen (anti-HBe). All sera were tested for HB sAg, anti-HBs and anti-HBc but for the detection of HBeAg and anti-HBe , only samples positive for HBsAg were examined. Main results. The mal e-to-female ratio in rural and urban settings was 0.82 and 0.66 respec tively. The median age for males and females in rural areas was 21 and 22 years and 28 and 26 years respectively in urban areas. The overall prevalence of HBsAg was 15.4% (males 16.8%, females 14.3%). The diffe rence between sexes was consistent in all age groups and statistically significant (P < 0.05). The prevalences in urban and rural areas were almost identical (15.7% v. 15.3%). However. the prevalence was signif icantly higher among males in the age group 40 - 49 years in urban are as compared with rural areas (P < 0.0001). Using the case-referent app roach, with HbsAg-positive patients as cases and HBsAg-negative ones a s referents, the crude odds ratio for rural areas compared with urban areas was 0,97. However, standardisation for year of data collection a nd province resulted in a relative risk of 2.0, i.e. the risk of being HBsAg-positive in rural areas is twice as high as in urban areas. Sim ilarly, the crude odds ratio for females compared with males was 0.83, and was reduced significantly to 0.7 when standardised for year of da ta collection and province. The prevalences of HBeAg, anti-HBe, anti-H Bs and anti-HBc were 25%, 25%, 45% and 36% respectively. The prevalenc es of anti-HBs and anti-HBc increased continuously with age and were a bout 70% higher in the age group 50 years and above compared with thos e under 20 years, The prevalence of any of the HBV markers - HBsAg, an ti-HBs or anti-HBc - was 66% in males and 61% in females. Conclusions. The results indicate that hepatitis B is hyperendemic in both rural a nd urban areas of Zimbabwe.