Seroprevalence of measles and natural rubella antibodies among children in Bangui, Central African Republic

Alexandre Manirakiza,Régis M'Bary Daba,Ionela Gouandjika-Vasilache,Stephen Sosler,Jean Marie Kipela

doi:10.1186/1471-2458-11-327

Abstract

BackgroundPassively acquired maternal antibodies are necessary to protect infants against circulating measles virus until they reach the eligible age of vaccination. Likewise, high levels of population immunity must be achieved and maintained to reduce measles virus transmission. This study was undertaken to (1) assess the presence of maternally acquired measles-specific IgG antibodies among infants less than 9 months of age in Bangui, Central African Republic and (2) determine the immune status of vaccination-age children and the concordance with reported vaccination status. A secondary objective was to describe the presence of rubella-specific IgG antibody in the study population.MethodsVaccination history and blood samples were collected from 395 children using blotting paper. Samples were analyzed for the presence of measles-specific IgG antibodies using commercial ELISA kits.ResultsMeasles-specific IgG antibodies were detected in 51.3% of vaccinated children and 27.6% of non-vaccinated children. Maternally derived measles IgG antibodies were present in only 14.8% of infants aged 0-3 months and were absent in all infants aged 4-8 months. The presence of IgG-specific measles antibodies varied among children of vaccination age, from 57.3% for children aged 9 months to 5 years, to 50.6% for children aged 6-9 years and 45.6% for chidren aged 10 years and above. The overall prevalence of rubella-specific IgG was 55.4%, with a high prevalence (87.4%) among children over 10 years of age.ConclusionThe findings suggest that despite efforts to accelerate measles control by giving a second dose of measles vaccine, a large number of children remain susceptible to measles virus. Further research is required to determine the geographic extent of immunity gaps and the factors that influence immunity to measles virus in the Central African Republic.

Highlights

Acquired maternal antibodies are necessary to protect infants against circulating measles virus until they reach the eligible age of vaccination
A second dose of measles-containing vaccine (MCV) given during supplemental immunization activities played a vital role in raising population immunity levels
Study population characteristics and vaccination status The study population consisted of 395 children recruited from the outpatient care wards of two health centers (42.8%) and seven kindergartens, primary and secondary schools (57.2%)

Summary

Introduction

Acquired maternal antibodies are necessary to protect infants against circulating measles virus until they reach the eligible age of vaccination. High levels of population immunity must be achieved and maintained to reduce measles virus transmission. This study was undertaken to (1) assess the presence of maternally acquired measles-specific IgG antibodies among infants less than 9 months of age in Bangui, Central African Republic and (2) determine the immune status of vaccination-age children and the concordance with reported vaccination status. Since 2000, significant progress has been made to reduce the global burden of measles. Nowhere has this achievement been more pronounced than in Africa. A second dose of measles-containing vaccine (MCV) given during supplemental immunization activities played a vital role in raising population immunity levels, . Where routine immunization coverage remains low and systems are weak, supplemental activities have been shown to be an effective mechanism for raising population immunity levels

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