Hepatitis E outbreak in the health district of Bocaranga-Koui, Central African Republic, 2018-2019.

BACKGROUND: Hepatitis E virus (HEV) is a major public health disease causing large outbreaks and sporadic cases of acute hepatitis. We investigated an outbreak of HEV infection that occurred in September 2018 in the health district (HD) of Bocaranga-Koui, located in the northwestern part of Central African Republic (CAR). METHODS: Blood samples were collected from 352 patients aged 0-85 years suspected to be infected with yellow fever (YF), according to the World Health Organization YF case definition. The notification forms from recorded cases were used. Water consumed in the HD were also collected. Human samples found negative for anti-YF IgM were then tested by ELISA for anti-HEV IgM and IgG antibodies. Positive anti-HEV (IgM and/or IgG) samples and collected water were then subjected to molecular biology tests using a real time RT-PCR assay, followed by a nested RT-PCR assay for sequencing and phylogenetic analysis. RESULTS: Of the 352 icterus patients included, anti-HEV IgM was found in 142 people (40.3%) and anti-HEV IgG in 175 (49.7%). Although HEV infection was detected in all age groups, there was a significant difference between the 0-10 age groups and others age groups (P = 0.001). Elevated levels of serum aminotransferase were observed in anti-HEV IgM-positive subjects. Phylogenetic analysis showed HEV genotype 1e in infected patients as well as in the contaminated water. CONCLUSION: This epidemic showed that CAR remains an HEV-endemic area. The genotype 1e strain was responsible for the HEV outbreak in Bocaranga-Koui HD. It is necessary to implement basic conditions of hygiene and sanitation to prevent further outbreaks of a HEV epidemics, to facilitate access to clean drinking water for the population, to launch intensive health education for basic hygiene measures, to sett up targeted hygiene promotion activities and, finally, to ensure that formal health care is available.

Molecular characterization of measles viruses in Central African Republic, 2012-2016.

Despite being preventable through vaccination, measles is still one of the most important causes of morbidity and mortality in young children in Africa. In 2015, several African countries, including the Central African Republic (CAR), began implementing national measles elimination programs. However, measles remains a public health problem in Africa, particularly in the CAR. A retrospective study was conducted at the Institut Pasteur de Bangui, using blood samples (n = 255) and oral swabs (n = 7) collected between January 2012 and December 2016 from measles IgM-positive cases, to attempt genotyping of circulating measles virus strains. Overall, 50 samples were positive by real-time polymerase chain reaction, and 40 sequences of acceptable quality were obtained. The phylogenetic analysis showed that 38 strains belonged to genotype B3 suggesting that this genotype was endemic in the CAR during the study period. No genotype B2 sequences were detected, suggesting that this genotype is no longer present in the CAR.

[Animal enteroviruses: a glimpse of a wide evolutionary landscape]. / Entérovirus des animaux : lumière sur l'immensité de l'espace évolutif des entérovirus.

The genus Enterovirus (family Picornaviridae) contains numerous viruses, most of which have been identified in humans. Among them, the three serotypes of poliovirus, coxsackieviruses A and B, echoviruses, rhinoviruses and other enteroviruses (EVs) responsible in humans for a wide spectrum of clinical manifestations. There are also 60 identified EVs in different mammals. Some have been found in both humans and animals, demonstrating the possibility of zoonotic transmission of certain EVs. Compared to human EVs, genetic and epidemiological data for animal EVs are scarce. However, the detection of EV in various species of mammals and their presence on all continents suggest that the number of EV still to be discovered is very important. Some EVs found in animals have characteristics never seen in human EVs. Furthermore, the unique phylogenetic relationships observed between animal EVs raise interesting questions about the rules that govern the evolution of these viruses. The aim of this review is to present the salient data on animal EVs and to highlight the questions they raise.

Animal enteroviruses: a glimpse of a wide evolutionary landscape.

The genus Enterovirus (family Picornaviridae) contains numerous viruses, most of which have been identified in humans. Among them, the three serotypes of poliovirus, coxsackieviruses A and B, echoviruses, rhinoviruses and other enteroviruses (EVs) responsible in humans for a wide spectrum of clinical manifestations. There are also 60 identified EVs in different mammals. Some have been found in both humans and animals, demonstrating the possibility of zoonotic transmission of certain EVs. Compared to human EVs, genetic and epidemiological data about animal EVs are scarce. However, the detection of EVs in various species of mammals and their presence on all continents suggest that the number of EVs still to be discovered is very important. Some EVs found in animals have characteristics never seen in human EVs. Furthermore, the unique phylogenetic relationships observed between some animal EVs raise interesting questions about the rules that govern the evolution of these viruses. The aim of this review is to present the salient data on animal EVs and to highlight the questions they raise.

Measles.

Measles is a highly contagious, potentially fatal, but vaccine-preventable disease caused by measles virus. Symptoms include fever, maculopapular rash, and at least one of cough, coryza, or conjunctivitis, although vaccinated individuals can have milder or even no symptoms. Laboratory diagnosis relies largely on the detection of specific IgM antibodies in serum, dried blood spots, or oral fluid, or the detection of viral RNA in throat or nasopharyngeal swabs, urine, or oral fluid. Complications can affect many organs and often include otitis media, laryngotracheobronchitis, pneumonia, stomatitis, and diarrhoea. Neurological complications are uncommon but serious, and can occur during or soon after the acute disease (eg, acute disseminated encephalomyelitis) or months or even years later (eg, measles inclusion body encephalitis and subacute sclerosing panencephalitis). Patient management mainly involves supportive therapy, such as vitamin A supplementation, monitoring for and treatment of secondary bacterial infections with antibiotics, and rehydration in the case of severe diarrhoea. There is no specific antiviral therapy for the treatment of measles, and disease control largely depends on prevention. However, despite the availability of a safe and effective vaccine, measles is still endemic in many countries and causes considerable morbidity and mortality, especially among children in resource-poor settings. The low case numbers reported in 2020, after a worldwide resurgence of measles between 2017 and 2019, have to be interpreted cautiously, owing to the effect of the COVID-19 pandemic on disease surveillance. Disrupted vaccination activities during the pandemic increase the potential for another resurgence of measles in the near future, and effective, timely catch-up vaccination campaigns, strong commitment and leadership, and sufficient resources will be required to mitigate this threat.

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

OBJECTIVES: Rubella cases in the Central African Republic (CAF) are currently identified during measles surveillance. This study aimed to investigate rubella epidemiology between 2015 and 2016 and to provide baseline genotype data for monitoring future rubella control efforts. METHODS: 831 measles IgM negative or equivocal sera from 2015/2016 were tested for rubella IgM antibodies and 350 rubella IgM positive sera collected between 2008 and 2016 were selected for PCR and sequencing. RESULTS: 411 of the 831 sera (49.5%) were rubella IgM positive and most cases (n=391, 95.1%) occurred between January and April. Most patients were between 5 and 9 years old (50.2%) and more than half of the rubella cases (56.7%) originated from the capital Bangui. Genotype information was obtained for 37 of the 350 selected rubella IgM-positive specimens, with the majority of the patients originating from Bangui (n=24, 64.9%) and sequences covering all years except 2009. Phylogenetic analysis identified genotypes 1E (n=12), 1G (n=5) and 2B (n=20), with 2B being detected from 2014 onwards. CONCLUSIONS: Our study confirmed the important role of rubella as a rash and fever disease in CAF and provided comprehensive data on rubella epidemiology and the first information on rubella genotypes in the country.

Whole gene analysis of a genotype G29P[6] human rotavirus strain identified in Central African Republic.

OBJECTIVE: Rotavirus A (RVA) remains the main causative agent of gastroenteritis in young children and the young of many mammalian and avian species. In this study we describe a RVA strain detected from a 6-month-old child from Central African Republic (CAR). RESULTS: We report the 11 open reading frame sequences of a G29-P[6]-I2-R2-C2-M2-A2-N2-T2-E2-H2 rotavirus strain, RVA/Human-wt/CAR/CAR91/2014/G29P[6]. Nine genes (VP1-VP3, VP6, NSP1-NSP5) shared 90-100% sequence similarities with genogroup 2 rotaviruses. Phylogenetically, backbone genes, except for VP3 and NSP4 genes, were linked with cognate gene sequences of human DS-1-like genogroup 2, hence their genetic origin. The VP3 and NSP4 genes, clustered genetically with both human and animal strains, an indication genetic reassortment human and animal RVA strains has taken place. The VP7 gene shared nucleotide (93-94%) and amino acid (95.5-96.7%) identities with Kenyan and Belgian human G29 strains, as well as to buffalo G29 strain from South Africa, while the VP4 gene most closely resembled P[6]-lineage I strains from Africa and Bangladesh (97%).

Vaccine-Derived Polioviruses, Central African Republic, 2019.

Since May 2019, the Central African Republic has experienced a poliomyelitis outbreak caused by type 2 vaccine-derived polioviruses (VDPV-2s). The outbreak affected Bangui, the capital city, and 10 districts across the country. The outbreak resulted from several independent emergence events of VDPV-2s featuring recombinant genomes with complex mosaic genomes. The low number of mutations (<20) in the viral capsid protein 1-encoding region compared with the vaccine strain suggests that VDPV-2 had been circulating for a relatively short time (probably <3 years) before being isolated. Environmental surveillance, which relies on a limited number of sampling sites in the Central African Republic and does not cover the whole country, failed to detect the circulation of VDPV-2s before some had induced poliomyelitis in children.

Genetic and phenotypic characterization of recently discovered enterovirus D type 111.

Members of the species Enterovirus D (EV-D) remain poorly studied. The two first EV-D types (EV-D68 and EV-D70) have regularly caused outbreaks in humans since their discovery five decades ago but have been neglected until the recent occurrence of severe respiratory diseases due to EV-D68. The three other known EV-D types (EV-D94, EV-D111 and EV-D120) were discovered in the 2000s-2010s in Africa and have never been observed elsewhere. One strain of EV-D111 and all known EV-D120s were detected in stool samples of wild non-human primates, suggesting that these viruses could be zoonotic viruses. To date, EV-D111s are only known through partial genetic sequences of the few strains that have been identified so far. In an attempt to bring new pieces to the puzzle, we genetically characterized four EV-D111 strains (among the seven that have been reported until now). We observed that the EV-D111 strains from human samples and the unique simian EV-D111 strain were not phylogenetically distinct, thus suggesting a recent zoonotic transmission. We also discovered evidences of probable intertypic genetic recombination events between EV-D111s and EV-D94s. As recombination can only happen in co-infected cells, this suggests that EV-D94s and EV-D111s share common replication sites in the infected hosts. These sites could be located in the gut since the phenotypic analysis we performed showed that, contrary to EV-D68s and like EV-D94s, EV-D111s are resistant to acid pHs. We also found that EV-D111s induce strong cytopathic effects on L20B cells, a cell line routinely used to specifically detect polioviruses. An active circulation of EV-D111s among humans could then induce a high number of false-positive detection of polioviruses, which could be particularly problematic in Central Africa, where EV-D111 circulates and which is a key region for poliovirus eradication.

Epidemiologic profile of measles in Central African Republic: A nine year survey, 2007-2015.

INTRODUCTION: Measles remains a major public health problem in many developing countries in which vaccination coverage is poor, as is the case in the Central African Republic (CAR). At the beginning of the 2000s, a surveillance system was established in the country, and samples from suspected cases are regularly tested in the laboratory for serological confirmation. Since 2007, when case-by-case monitoring with standardized laboratory databases and monitoring, was set up, no assessment have been performed. Therfore, 9 years later it seemed appropriate to make a first assessment. The aim of the study reported here was to describe the epidemiology of measles in the CAR on the basis of surveillance and laboratory data. METHOD: A descriptive retrospective study was conducted, based on the databases of the measles surveillance programme and of the Institut Pasteur laboratory in Bangui during the period 2007-2015. RESULTS: During this study period, the surveillance programme notified 3767 cases. Of these, 2795 (75%) were sent for laboratory confirmation, and 24.6% (687/2795) were confirmed serologically. Of the 1797 cases of measles declared during this period by the surveillance programme, 1110 (61.8%) were confirmed clinically or by epidemiological linkage. The majority of confirmed cases (83.7%; 575/687) occurred in children under 10 years, over half of whom (44.2%; 304/687) were aged 1-4 years. Epidemics occurred regularly between 2011 and 2015, with > 10% of laboratory-confirmed cases. The rate of laboratory investigation was < 80% between 2011 and 2013 but nearly 100% in the other years. CONCLUSION: Measles remains a common, endemic illness in the CAR. Improved detection will require better measles surveillance, increased vaccination coverage, revision of the investigation forms to include the WHO case definition and training of the health personnel involved in case-finding in the field.

Genetic Characterization of Enterovirus A71 Circulating in Africa.

We analyzed whole-genome sequences of 8 enterovirus A71 isolates (EV-A71). We confirm the circulation of genogroup C and the new genogroup E in West Africa. Our analysis demonstrates wide geographic circulation and describes genetic exchanges between EV-A71 and autochthonous EV-A that might contribute to the emergence of pathogenic lineages.

Factors associated with stunting in healthy children aged 5 years and less living in Bangui (RCA).

Stunting remains a major public health concern worldwide. Although its global prevalence is slowly decreasing, the actual number of affected children is still rising in Sub-Saharan Africa. In the Central African Republic (CAR), about one third of all children below the age of five are stunted. Stunting is correlated with many long-term consequences, including poor cognitive development and a higher rate of morbidity and mortality, making stunting a major contributor to poverty. In CAR, little is known about the factors that contribute to stunting. This study aimed at analysing, in a cross-sectional study, the main factors associated with stunting in a group of 414 children recruited between December 2011 and November 2013, aged five years or less and living in Bangui. For all children, demographic, socio-economic and anthropometric data were recorded and asymptomatic enteropathogen carriage was assessed in stool samples using classical microbiological assays. The study group had a mean age of 14.2±10 months. Fifty-eight percent (292/414) were boys, and 36 percent (148/414) exhibited stunted growth. Of the stunted children, 51% (75/148) showed a moderate delay in linear growth for their age group [height-for-age z-score (HAZ) between -2 and -3 SD] while 49% (73/148) presented a severe delay (HAZ < -3). Factors significantly associated with stunting included gender (aOR: 1.67; 95% CI: 1.07; 2.62 for boys compared to girls) and age (aOR of 3.98 (95% CI: 2.45; 6.46) for toddlers and aOR 4.42 (95% CI: 2.36; 8.28) for children compared to infants). Most importantly, we identified being overweight [weight-for-height z-score (WHZ) > 2 SD; aOR: 3.21; 95% CI: 1.50; 6.90 of overweight compared to normal weight] as also being significantly associated with stunting. This is the first study showing that even in the poorest countries of the world there is an association of stunting with being overweight.

Epidemiological Surveillance of Poliomyelitis During the Military and Political Conflict in the Central African Republic, 2013 and 2014.

BACKGROUND: Since December 2012, the Central African Republic (CAR) has been undergoing a severe military and political conflict. This situation has resulted in general insecurity and total disorganization of surveillance activities, including those for acute flaccid paralysis (AFP). In this study, we used laboratory data to evaluate surveillance of AFP in 2013 and 2014, the most critical period of the conflict. METHODS: The laboratory data on AFP were analyzed retrospectively for the age, sex, vaccination status (oral poliovirus vaccines), and geographical origin of the samples. The χ2 test was used, with P < .05 as the threshold for significance. RESULTS: Decreased activity of AFP surveillance of 57% was registered in 2013 and 36% in 2014 compared with previous years. Only 37.3% and 49.7% of children with AFP were vaccinated in 2013 and 2014, respectively, but no wild poliovirus or vaccine-derived poliovirus (VDPV) was isolated. Laboratory performance concerning the timeliness of cell culture and intratypic differentiation/VDPV results was only 65.5% and 66.7% of the target in 2013 but reached 95.5% and 100% in 2014. CONCLUSIONS: All personnel involved in the monitoring of AFP must be mobilized to improve vaccination coverage and surveillance activities in the CAR.

Epidemiology of primary rubella infection in the Central African Republic: data from measles surveillance, 2007-2014.

BACKGROUND: Although rubella is generally considered a benign childhood disease, infection of a pregnant woman can cause foetal congenital rubella syndrome, which results in embryo-foetal disease and malformations. The syndrome is still a public health problem in developing countries where the vaccine has not yet been introduced, such as the Central African Republic (CAR). The aim of the study reported here was to define the epidemiology of primary rubella infection, in order to determine its effect on morbidity rates in the country. METHODS: Data derived from epidemiological surveillance of measles and rubella were analysed retrospectively between 1 January 2007 and 31 December 2014. The database includes cases of suspected measles, according to the WHO clinical case definition. In this algorithm, samples that are negative or doubtful by ELISA for measles (presence of immunoglobulin M) are tested in another ELISA for detection of rubella-specific IgM. Descriptive analyses were conducted for socio-demographic characteristics, including age, sex and health region, for patients tested for rubella. RESULTS: Of the sera tested for rubella, 30.2 % (425/1409) were positive, 62.3 % (878/1409) were negative, and 7.5 % (106/1409) were doubtful. Among the 425 positive cases, 213 (50.1 %) were female and 212 (40.9 %) were male with a sex ratio of 1.03. The mean age was 8 years (range, 6-37 years). The highest prevalence (47.3 %; 116/425) was seen in 2007 and the lowest (8.9 %; 11/425) in 2012. Primary infections were always more frequent during the first 3 months of the year, with a peak at the same time, between January and February which is the hottest period of the year in the CAR. In both sexes, rubella IgM was rarely found before the age of 1 year (0.5 %; 2/425). The highest rate (43.5 %; 185/425) was observed at ages 5-9 years; however, at least 8 % (18/213) of girls aged 15 or more had primary infections. CONCLUSIONS: Sentinel sites for surveillance of congenital rubella syndrome are urgently needed, and introduction of vaccination against rubella in the Expanded Programme of Immunization should be considered, to ensure immunization of girls of reproductive age.

Molecular surveillance of rotavirus infection in Bangui, Central African Republic, October 2011-September 2013.

BACKGROUND: The World Health Organization (WHO) recommends the introduction of rotavirus vaccine in the immunization program of all countries. In the Central African Republic (CAR), sentinel surveillance for rotavirus gastroenteritis was established in 2011 by the Ministry of Health, with the support of the Surveillance en Afrique Centrale Project (SURVAC). The purpose of this study was to assess the burden of rotavirus gastroenteritis and to identify rotavirus strains circulating in CAR before the introduction of rotavirus vaccine planned for this year, 2014. METHODS: One sentinel site and one laboratory at the national level were designated by the CAR Ministry of Health to participate in this surveillance system. Stool samples were collected from children who met the WHO rotavirus gastroenteritis case definition (WHO, 2006). The samples were first screened for group A rotavirus antigen by enzyme immunoassay (EIA), and genotyping assays performed using a multiplex reverse transcriptase PCR (RT-PCR) technique. RESULTS: Between October 2011 and September 2013, 438 stool samples were collected and analyzed for detection of rotavirus antigen; 206 (47%) were positive. Among the 160 (78%) that could be genotyped, G2P[6] was the predominant strain (47%) followed by G1P[8] (25%) and G2P[4] (13%). CONCLUSIONS: Almost half of stool samples obtained from children hospitalized with gastroenteritis were positive for rotavirus. These baseline rotavirus surveillance data will be useful to health authorities considering rotavirus vaccine introduction and for evaluating the efficacy of rotavirus vaccine once it is introduced into the routine immunization system.

Characterization of hepatitis delta virus in sub-Saharan Africa.

Hepatitis D virus (HDV) is a satellite of hepatitis B virus (HBV), and infection with this virus aggravates acute and chronic liver disease. While HBV seroprevalence is very high across sub-Saharan Africa, much less is known about HDV in the region. In this study, almost 2,300 blood serum samples from Burkina Faso (n=1,131), Nigeria (n=974), Chad (n=50), and the Central African Republic (n = 118) were screened for HBV and HDV. Among 743 HBsAg-positive serum samples, 74 were positive for HDV antibodies and/or HDV RNA, with considerable differences in prevalence, ranging from <2% (pregnant women from Burkina Faso) to 50% (liver patients from Central African Republic). HDV seems to be much more common in chronic liver disease patients in the Central African Republic (CAR) than in similar cohorts in Nigeria. In a large nested mother-child cohort in Burkina Faso, the prevalence of HDV antibodies was 10 times higher in the children than in their mothers, despite similar HBsAg prevalences, excluding vertical transmission as an important route of infection. The genotyping of 16 full-length and 8 partial HDV strains revealed clade 1 (17/24) in three of the four countries, while clades 5 (5/24) and 6 (2/24) were, at least in this study, confined to Central Nigeria. On the amino acid level, almost all our clade 1 strains exhibited a serine at position 202 in the hepatitis D antigen, supporting the hypothesis of an ancient African HDV-1 subgroup. Further studies are required to understand the public health significance of the highly varied HDV prevalences in different cohorts and countries in sub-Saharan Africa.

Measles outbreak in Northern Central African Republic 3 years after the last national immunization campaign.

BACKGROUND: Despite huge efforts to promote widespread vaccination, measles remains an important cause of morbidity and mortality worldwide, especially in African children. In March 2011, an abnormally high number of cases were reported from the Ouham Prefecture, Central African Republic to the national measles case-based surveillance system. In response, reactive vaccination activities were implemented. The aims of this study were to investigate this outbreak and describe the response. METHODS: Measles cases were defined according to WHO recommendations. In the first weeks of the outbreak, blood samples were collected and sent to the Institut Pasteur in Bangui for laboratory confirmation by detection of IgM antibodies against measles virus. In addition, a portion of viral RNA was amplified from 5 IgM positive patient samples and the amplicons were sequenced for phylogenetic analysis. RESULTS: Between March and September 2011, 723 clinical cases originated from the Ouham Prefecture, including 2 deaths, were reported. Amongst 59 blood samples collected, 49 were positive for the detection of IgM. A high number of self-declared vaccinated subjects (31%) were found amongst the cases. Most of the cases were under 5 years. The causative virus was found to belong to genotype B3.1. In response, 2 sub-national supplementary immunization activities were quickly conducted and limited this outbreak to mainly 2 sub-prefectures. CONCLUSIONS: This outbreak was the largest epidemic of measles in CAR since 2002. Its occurrence, 3 years after the last national immunization campaign, highlights the necessity to pursue efforts and improve and extend immunization programs in order to reach measles elimination goal in Africa.

Molecular characterization of human enteroviruses in the Central African Republic: uncovering wide diversity and identification of a new human enterovirus A71 genogroup.

Human enteroviruses (HEV) are among the most common viruses infecting humans. Their circulation has been widely studied in most parts of the world but not in sub-Saharan Africa, where poliomyelitis remains prevalent. We report here the molecular characterization of 98 nonpoliovirus (non-PV) HEV strains isolated from 93 randomly selected cell culture-positive supernatants from stool samples collected from 1997 through 2006 from children with acute flaccid paralysis living in the Central African Republic (CAR). The isolates were typed by sequencing the VP1 coding region and sequenced further in the VP2 coding region, and phylogenetic studies were carried out. Among the 98 VP1 sequences, 3, 74, 18, and 3 were found to belong to the HEV-A, -B, -C, and -D species, respectively. Overall, 42 types were detected. In most cases, the VP2 type was correlated with that of the VP1 region. Some of the isolates belonged to lineages that also contain viruses isolated in distant countries, while others belonged to lineages containing viruses isolated only in Africa. In particular, one isolate (type EV-A71) did not fall into any of the genogroups already described, indicating the existence of a previously unknown genogroup for this type. These results illustrate the considerable diversity of HEV isolates from the stools of paralyzed children in the CAR. The presence of diverse HEV-C types makes recombination between poliovirus and other HEV-C species possible and could promote the emergence of recombinant vaccine-derived polioviruses similar to those that have been implicated in repeated poliomyelitis outbreaks in several developing countries.

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

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 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. 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.