Epidemiology and Infection



Sero-epidemiology of rubella in the urban population of Addis Ababa, Ethiopia


F. T. CUTTS a1c1, A. ABEBE a2, T. MESSELE a2, A. DEJENE a2, F. ENQUSELASSIE a3a4, W. NIGATU a2 and D. J. NOKES a4
a1 Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK
a2 Ethiopian Health and Nutrition Research Institute, PO Box 1242, Addis Ababa, Ethiopia
a3 Department of Community Health, Faculty of Medicine, University of Addis Ababa, PO Box 1176, Addis Ababa, Ethiopia
a4 Ecology and Epidemiology Group, Department of Biological Sciences, University of Warwick, Coventry, CV4 7AL, UK

Abstract

We conducted a community-based cluster sample survey of rubella sero-epidemiology in Addis Ababa, Ethiopia in 1994. Among 4666 individuals for whom complete data were available, rubella antibody prevalence was 91% (95% confidence interval: 90, 92). On multivariable analysis, seroprevalence was lower among individuals who were resident in Addis Ababa for 1 year or less. Approx. 50% seroprevalence was attained by age 4 years, and the estimated average age at infection was 5·2 years. The highest age-specific force of infection was estimated to occur in 5- to 9-year-olds. The early age at infection corresponded with a low estimated incidence of congenital rubella syndrome (CRS) of 0·3 per 1000 live births, equivalent to nine cases of CRS in 1994. The predicted critical level of immunity for elimination of rubella via vaccination was 85–91%, requiring 89–96% coverage with a vaccine of 95% effectiveness. Unless very high coverage of rubella vaccine could be guaranteed, the introduction of childhood vaccination could increase the incidence of CRS in Addis Ababa.

(Accepted November 20 1999)


Correspondence:
c1 Author for correspondence.


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