Descriptive epidemiology of rubella disease and associated virus strains in Uganda.

Rubella virus causes a mild disease; however, infection during the first trimester of pregnancy may lead to congenital rubella syndrome (CRS) in over 80% of affected pregnancies. Vaccination is recommended and has been shown to effectively reduce CRS incidence. Uganda plans to introduce routine rubella vaccination in 2019. The World Health Organization recommends assessing the disease burden and obtaining the baseline molecular virological data before vaccine introduction. Sera collected during case-based measles surveillance from January 2005 to July 2018 were tested for rubella immunoglobulin M (IgM) antibodies. Sera from confirmed rubella outbreaks from January 2012 to August 2017 were screened using real-time reverse-transcription polymerase chain reaction (RT-PCR); for positive samples, a region within the E1 glycoprotein coding region was amplified and sequenced. Of the 23 196 suspected measles cases serologically tested in parallel for measles and rubella, 5334 (23%) were rubella IgM-positive of which 2710 (50.8%) cases were females with 2609 (96.3%) below 15 years of age. Rubella IgM-positive cases were distributed throughout the country and the highest number was detected in April, August, and November. Eighteen (18%) of the 100 sera screened were real-time RT-PCR-positive of which eight (44.4%) were successfully sequenced and genotypes 1G and 2B were identified. This study reports on the seroprevalence and molecular epidemiology of rubella. Increased knowledge of former and current rubella viruses circulating in Uganda will enhance efforts to monitor the impact of vaccination as Uganda moves toward control and elimination of rubella and CRS.

Phylogenetic analysis of rubella viruses identified in Uganda, 2003-2012.

Molecular data on rubella viruses are limited in Uganda despite the importance of congenital rubella syndrome (CRS). Routine rubella vaccination, while not administered currently in Uganda, is expected to begin by 2015. The World Health Organization recommends that countries without rubella vaccination programs assess the burden of rubella and CRS before starting a routine vaccination program. Uganda is already involved in integrated case-based surveillance, including laboratory testing to confirm measles and rubella, but molecular epidemiologic aspects of rubella circulation have so far not been documented in Uganda. Twenty throat swab or oral fluid samples collected from 12 districts during routine rash and fever surveillance between 2003 and 2012 were identified as rubella virus RNA positive and PCR products encompassing the region used for genotyping were sequenced. Phylogenetic analysis of the 20 sequences identified 19 genotype 1G viruses and 1 genotype 1E virus. Genotype-specific trees showed that the Uganda viruses belonged to specific clusters for both genotypes 1G and 1E and grouped with similar sequences from neighboring countries. Genotype 1G was predominant in Uganda. More epidemiological and molecular epidemiological data are required to determine if genotype 1E is also endemic in Uganda. The information obtained in this study will assist the immunization program in monitoring changes in circulating genotypes.

Possible interruption of measles virus transmission, Uganda, 2006-2009.

To determine what measles virus genotype(s) circulated in Uganda after strategic interventions aimed at controlling/eliminating measles, we examined samples obtained during 2006-2009 and found only genotype B3.1, which had not been previously detected. Kenya was the likely source, but other countries cannot be excluded.