Rubella epidemiology in the Central African Republic, 2015-2016 and molecular characterization of virus strains from 2008-2016

Epidemiology of Rubella Virus in a Fragile and Conflict-affected Setting - A Retrospective Analysis of 11 Years Case-based Data in South Sudan

Introduction

Since establishing routine immunization services in what was then known as Sudan in 1974, South Sudan has not yet introduced the rubella-containing vaccine into its national immunization schedule. This study aims to assess the burden of rubella infection within the existing measles case-based surveillance framework to provide evidence supporting advocacy for introducing the rubella-containing vaccine into the national immunization program.

Methods

This study conducted a retrospective descriptive analysis of rubella infection using measles case-based surveillance data from 2013 to 2023. Data were analyzed with descriptive statistics and logistic regression using Epi Info, version 7.

Results

During the study period, 17,987 suspected measles cases were reported, with 4944 serum samples collected. Of these, 2083 (42.1%) were positive for measles immunoglobulin M antibodies. Among 2861 samples that tested negative or indeterminate for measles, 678 (23.7%) tested positive for rubella immunoglobulin M antibodies. The study observed a significant increase in rubella positivity rates from 1.6% in 2014 to 34.4% in 2020. Logistic regression analysis showed that rubella infection was significantly more likely among children aged 5-9 years (odds ratio [OR] = 2.234; 95% confidence interval [CI]; 1.468-3.473, P < .001), 10-14 years (OR = 2.101; 95% CI, 1.570-4.428; P < .001), and 1-4 years (OR = 1.733; 95% CI, 1.149-2.687; P = .003), compared to children aged younger than 1 year (reference group). Rubella positivity was also slightly higher in urban settings than rural areas (OR = 1.139; 95% CI, 1.004-1.527; P = .034). Rubella cases demonstrated clear seasonality, with increased cases occurring from December and peaking in March.

Conclusions

The study identified a high prevalence of rubella among young children, particularly those aged 1-9 years and in urban areas, highlighting the need for targeted vaccination strategies. These findings strongly support introducing the rubella vaccine into the national immunization program.

Viral etiology of measles-like rash in Guinean children during the COVID epidemic in 2022

Covid-19 in West Africa masked outbreaks of vaccine-preventable diseases such as the measles epidemic in children in Guinea in 2021-2022 characterized by a lack of confirmation of suspected clinical cases. During weeks 13-22 of 2022, saliva samples were collected from 213 children (3-60 months old) with measles-like symptoms within the St Gabriel dispensary in Conakry. Samples were processed in Virus Transport Medium (VTM) and tested on the same day by triplex reverse transcriptase -real-time polymerase chain reaction for Measles, Rubella and RNaseP. Samples were also tested for HHV6 and Parvovirus B19, viruses causing clinical signs similar to measles. We confirmed 146 (68.5%) measles cases, 27 (12.7%) rubella, 5 (2.3%) double-positive measles-rubella, 35 (16.4%) HHV-6 and 8 (3.75%) Parvovirus B19. To test the assay's robustness, 27 samples were kept at 26-30°C. Measles and rubella were still detected after 7 days at 26-30°C, and after 21 days measles and rubella were still detectable in all samples but one. Sequencing indicated the circulation of the B3 measles genotype, as expected in West Africa. This study highlights the robustness of the measles/rubella diagnostic test on saliva samples stored in VTM. The high level of rubella detection questioned the single valence measles vaccination strategy.

Rubella virus genotype 2B endemicity and related utility of serum-based molecular characterization in Uganda

There are 13 globally recognized rubella virus genotypes of which only 2 (1E and 2B) have been detected recently. The largest percentage of all reported rubella virus sequences come from China and Japan with Africa reporting limited data. In a bid to address the lack of rubella genotype data in Uganda and the World Health Organization Africa region, we sought to characterize rubella viruses retrospectively using sera collected from suspected measles patients that turned out rubella IgM positive.Seven sequences belonging to genotype 2B sub-lineage 2B-L2c were obtained. These sequences clustered with other genotype 2B sequences previously reported from Uganda. None of the other genotypes (1E and 1G) reported from Uganda in the earlier years were detected. In addition, none of the sequences were obtained after the introduction of the measles-rubella containing vaccine. The above highlight the need for continuous rubella virological surveillance to confirm interruption of endemic rubella genotype circulation.

Measles and Rubella Incidence and Molecular Epidemiology in Senegal: Temporal and Regional Trends during Twelve Years of National Surveillance, 2010-2021

We investigated the epidemiology of measles and rubella infections in Senegal based on data from twelve consecutive years of laboratory-based surveillance (2010−2021) and conducted phylogenetic analyses of circulating measles viruses. Sera from measles-suspected cases were collected and tested for measles and rubella-specific IgM antibodies using enzyme-linked immunosorbent assays (ELISA). Throat swabs were collected from patients with clinically diagnosed measles for confirmation by reverse-transcription polymerase chain reaction (RT-PCR) and viral genotyping. Among 8082 laboratory-tested specimens from measles-suspected cases, serological evidence of measles and rubella infection was confirmed in 1303/8082 (16.1%) and 465/6714 (6.9%), respectively. The incidence of rubella is now low—0.8 (95% CI 0.4−1.3) cases per million people in 2021—whereas progress towards measles pre-elimination targets (<1.0 case per million people per year) appears to have stalled; there were 10.8 (95% CI 9.3−12.5) cases per million people in 2021. Phylogenetic analyses revealed that all Senegalese measles strains belonged to genotype B3. The rubella virus sequence obtained in this study was consistent with genotype 1C. Our national surveillance data suggest that despite their low incidence both measles and rubella remain endemic in Senegal with a concerning stagnation in the decline of measles infections that represents a significant challenge to the goal of regional elimination.

Epidemiological investigation and prevention and control strategies of rubella in Anhui province, China, from 2012 to 2021

Background

Rubella is a highly contagious viral infection with mild manifestations that occurs most often in children and young adults. Infection during pregnancy, especially during the first trimester, can result in an infant born with congenital rubella syndrome (CRS). The purpose of this paper is to analyze the characteristics of rubella epidemics in Anhui province from 2012 to 2021 and explore the prevention and control strategies of rubella.

Methods

A descriptive epidemiological approach was used to examine the epidemiological characteristics of rubella in Anhui Province between 2012 and 2021.

Results

From 2012 to 2021, a total of 4,987 cases of rubella were reported in Anhui province, with an average annual incidence of 8.11 per million, demonstrating an overall downward trend (χ² trend =3141.06, P < 0.01). The average yearly incidence of rubella in southern Anhui, central Anhui, and northern Anhui were 9.99 per million, 11.47 per million, and 4.50 per million, respectively, with statistically significant differences (χ² =792.50, P < 0.01). The male to female incidence ratio was 1.67:1, and the male incidence rate was higher than the female incidence rate. Most cases occurred among students, accounting for 56.59% of all cases, and the 10-34 age group accounted for ~73.71% of all cases. Regarding immunization history, 3.57% of cases had two doses or more, 6.62% had one dose, 16.40% had none, and the remainder were uncertain.

Conclusion

The incidence of rubella in Anhui province from 2012 to 2021 continued to decline, with regional variations observed. The 10-34-year-old population without a history of rubella vaccination is at high risk for the disease. It is suggested to carry out rubella vaccination and congenital rubella syndrome monitoring according to the actual situation.