Measles seroprevalence, outbreaks, and vaccine coverage in Rwanda

Abstract

Background: Measles outbreaks are reported after insufficient vaccine coverage, especially in countries recovering from natural disaster or conflict. We compared seroprevalence to measles in blood donors in Rwanda and Sweden and explored distribution of active cases of measles and vaccine coverage in Rwanda.

Methods: 516 Rwandan and 215 Swedish blood donors were assayed for measles-specific immunoglobulin G (IgG) by enzyme-linked immunosorbent assay (ELISA). Data on vaccine coverage and acute cases in Rwanda from 1980 to 2014 were collected, and IgM on serum samples and polymerase chain reaction (PCR) on nasopharyngeal (NPH) swabs from suspected measles cases during 2010–2011 were analysed.

Results: The seroprevalence of measles IgG was significantly higher in Swedish blood donors (92.6%; 95% CI: 89.1–96.1%) compared to Rwandan subjects (71.5%; 95% CI: 67.6–75.4%) and more pronounced <35 years of age. The OD values were significantly lower in the Rwandan blood donors as compared to Swedish subjects (p < 0.00001). However, effective measles vaccine coverage was concomitant with decrease in measles cases in Rwanda, with the exception of an outbreak in 1995 following the 1994 genocide. 76/544 serum samples were IgM positive and 21/31 NPH swabs were PCR positive for measles, determined by sequencing to be of genotype B3.

Conclusions: Measles seroprevalence was lower in Rwandan blood donors compared to Swedish subjects. Despite this, the number of reported measles cases in Rwanda rapidly decreased during the study period, concomitant with increased vaccine coverage. Taken together, the circulation of measles was limited in Rwanda and vaccine coverage was favourable, but seroprevalence and IgG levels were low especially in younger age groups.

Keywords:

• ELISA
• measles
• Rwanda
• seroprevalence
• vaccination

Acknowledgements

We are thankful to Maria Johansson at the Virological Laboratory, Sahlgren’s University Hospital, for her skilful technical assistance. We also thank Phionah Tushabe at the Uganda Virus Research Institute (UVRI) in Entebbe and Sheilagh Smit at the Centre for Vaccines and Immunology, National Institute for Communicable Diseases in Johannesburg, South Africa, for kind collaboration and support in retrieving measles PCR and genotyping results.

Disclosure statement

This research project received funds from the Swedish International Development Cooperation Agency (SIDA) and the LUA-ALF Foundation of Sahlgrens University Hospital, Gothenburg, Sweden.