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

Wednesday, 11th of December 2013

[source]BioMed Central[|source]

Since 2000, significant progress has been made to reduce the global burden of measles. Nowhere has this achievement been more pronounced than in Africa. As in the rest of the African Region, measles control in CAR improved markedly during the past decade. In spite of the gains, measles morbidity and mortality continue to be an important public health concern for Africas impoverished children, who have poorer access to vaccination and curative services. Moreover, the recent resurgence of measles outbreaks, cases and deaths is a necessary reminder of how short-lived immunity gains and progress can be. Therefore a more direct and complementary manner of assessing vaccination activities and the level of community protection against measles is to evaluate the immunoglobulin response of a population to a given vaccine antigen.

In this article, the authors assessed the presence of maternally acquired measles-specific antibodies in infants not yet eligible for MCV in routine services (children <9 months of age) in the capital city, Bangui and determined the immune status of vaccination-age children and the association with reported vaccination status. The report documents large number of children not protected against measles. The study also documents rapid loss of maternal protective antibodies that in turn widens periods of vulnerability of infants and suggests that the first dose of measles vaccine could be administered at an earlier age. More details are available at:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3112134/

 

Abstract

BACKGROUND: Passively 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.

METHODS: Vaccination 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.

RESULTS: Measles-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 children 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.

CONCLUSION: The 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.