Epidemiology and Infection



Seroepidemiology of hepatitis B virus in Addis Ababa, Ethiopia: transmission patterns and vaccine control


A. ABEBE a1, D. J. NOKES a2c1, A. DEJENE a3, F. ENQUSELASSIE a2a4, T. MESSELE a5 and F. T. CUTTS a6
a1 Virology and Rickettsiology Research Team, Ethiopian Health and Nutrition Research Institute (EHNRI), Addis Ababa, PO Box 1242, Ethiopia
a2 Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
a3 Biostatistics and Health Service Research Team, Ethiopian Health and Nutrition Research Institute, PO Box 1242, Addis Ababa, Ethiopia
a4 Department of Community Health, Faculty of Medicine, University of Addis Ababa, PO Box 1176, Addis Ababa, Ethiopia
a5 Immuno-Haematology and Pathology Research Team, Ethiopian Health and Nutrition Research Institute, PO Box 1242, Addis Ababa, Ethiopia
a6 Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1N 7HT, UK

Article author query
abebe a   [PubMed][Google Scholar] 
nokes d   [PubMed][Google Scholar] 
dejene a   [PubMed][Google Scholar] 
enquselassie f   [PubMed][Google Scholar] 
messele t   [PubMed][Google Scholar] 
cutts f   [PubMed][Google Scholar] 

Abstract

A community-based seroepidemiological survey of Addis Ababa, Ethiopia was conducted in 1994 to inform on the transmission dynamics and control of hepatitis B virus (HBV) infection. Venous blood from 4736 individuals under 50 years of age from 1262 households, selected using stratified cluster-sampling, was screened for HBV markers using commercial ELISAs. HBsAg prevalence was 7% (95% CI 6–8), higher in males (9%; 7–10) than females (5%; 4–6). HBeAg prevalence in HBsAg positives was 23% (18–29), and less than 1% of women of childbearing age were HBeAg positive. Overall HBV seroprevalence (any marker), rose steadily with age to over 70% in 40–49 year olds, indicating significant childhood and adult transmission. Estimated instantaneous incidence was 3–4/100 susceptibles/year, higher in males than females in 0–4 year olds, and peaking in early childhood and young adults. The age at which 50% had evidence of infection was around 20 years, and the herd immunity threshold is approximated at 63–77%. Addis Ababa is of intermediate-high HBV endemicity, with negligible perinatal transmission. Our main findings are the identification of a significant difference between males and females in the age-acquisition of HBV infection, and marked differences between age groups in HBV incidence rates. These results should target future research studies of underlying risk factors. Furthermore, we generate a crude estimate of the level of coverage of HBV vaccine that would be required to eliminate the virus from the study population.

(Accepted February 13 2003)


Correspondence:
c1 Welcome Trust Research Laboratories, Kenya Units, PO Box 230, Kilifi, Kenya.


Metrics