Background
Hepatitis C virus (HCV) infection is a bloodborne disease which is globally distributed that mainly affects developing countries. In 2019, an estimated 58 million chronic cases were reported in the world [
1], 75% of which occurred in low- and middle-income countries (LMIC) [
2]. Worldwide, new HCV infections occur in high-risk populations, including people who inject drugs (PWID) and men who have sex with men (MSM) [
3]. In sub-Saharan Africa, HCV is mainly transmitted via unsafe medical practices and contaminated blood transfusion [
4]. Other transmission routes include needlestick injury in healthcare workers, mother-to-child transmission (MTCT), and social practices such as piercing and tattooing [
3].
HCV infections are usually asymptomatic and silently progress over time. Up to 25% of new infections spontaneously resolve [
5], and the remaining evolve to chronicity with complications such as liver cirrhosis and hepatocellular carcinoma (HCC) [
3]. Since no vaccine is available to prevent HCV infection and its chronic consequences, screening and treatment of cases using effective direct-acting antivirals (DAA) are required [
6]. HCV antibody (anti-HCV) assays are typically positive within 4–10 weeks after the initial infection, persist lifelong, and indicate a current or past exposure to the virus [
7]. Thus, the WHO requires a confirmatory test by detecting HCV ribonucleic acid (HCV RNA) or core antigen (HCVcAg) [
8].
In Burkina Faso, a West African country, the epidemiologic patterns of HCV infection are poorly documented. The only nationwide study conducted in 2010 reported a seroprevalence of 3.6% (95% CI: 3.3–3.8) in the general population [
9]. In addition, various seroprevalence data classify the country among those of intermediate or high seroprevalence (seroprevalence ≥ 2% or ≥ 5%, respectively) [
10‐
12]. However, detailed characteristics of the infection in specific populations and geographic areas are scarce, representing a limitation for implementing effective control strategies. Thus, this study aimed to provide detailed knowledge on the epidemiologic profile of HCV infection in Burkina Faso by synthesizing data on HCV seroprevalence in various settings and populations at-risk in Burkina Faso. Secondary objectives included the prevalence of HCV RNA and the distribution of genotypes in the country.
Methods
Study design and guidelines
We conducted a systematic review with meta-analysis following the Joanna Briggs Institute guidelines for systematic reviews of studies reporting prevalence data [
13]. This manuscript is reported according to the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) recommendations [
14].
Study setting
Burkina Faso is a landlocked country in West Africa with an overall population of 20,487,979 people in 2019 [
15]. The country is divided into 13 regions, with the central region accounting for 14.8% of the total population. About one in four inhabitants live in rural areas. This developing country is characterized by the persistence of tropical infections and the epidemiological transition to non-transmissible diseases.
Data source and study selection
We searched the following databases to identify records published between 1990 and 2020: PubMed, Web of Science, Scopus, and African Index Medicus. A complete list of the search queries is shown in Additional file
1: Table S1. Besides, a manual search was conducted on African Journals Online (AJOL), Google Scholar, the reference lists of eligible reports, and the electronic library of the University Joseph Ki-Zerbo (
www.biblio-ujkz.com), the largest university in the country. The last search was conducted on July 1, 2020, and reports in English or French were eligible. After removing duplicates using the EndNote reference manager, two independent investigators (SO and JCRPO) screened the records based on their titles and abstracts. Those deemed relevant were retained for full-text review. Any report (journal article, conference abstract, government report) of HCV antibody testing among people living in Burkina Faso was considered for inclusion. Reports that did not mention sample size and number of cases (or prevalence) were excluded. Disagreements between the two investigators were solved by discussion. When there was no consensus, the final decision was made by a third investigator (ML).
A pre-piloted standardized electronic data extraction form was used to extract relevant data: authors names, year of publication, study setting, study design, sampling method, study period, characteristics of study subjects (age, sex, location, co-morbidities), sample size, number of participants positive for anti-HCV, and type of biological assay. We also extracted HCV RNA and genotyping data when available. In this paper, a “report” refers to any document mentioning HCV seroprevalence data, and a “study” relates to the measurement of anti-HCV antibodies in a given population or setting (rural/urban). Therefore, one report may describe multiple studies, and in this case, we extracted data for each study separately. When data were suspected to originate from the same source, only one publication was included.
Quality appraisal
Joanna Briggs Institute checklist for prevalence studies was used to appraise the methodological quality of the studies [
13]. Before independently using the tool, the reviewers agreed on the minimum acceptable information for each item. Sample size was considered adequate when more than 411 subjects were included. This was based on an assumed seroprevalence of 3.6% [
9], a precision of 1.8%, and a confidence level of 95%. For the sampling procedure, only probabilistic sampling was considered representative of the target population. Anti-HCV seroprevalence data was considered valid when the diagnostic was based on biological testing.
Data synthesis and analysis
We categorized the study populations into two groups based on the risk of HCV transmission. The low-risk group included the general population, blood donors, pregnant women, and children. People living with Human Immunodeficiency Virus (HIV), sex workers, MSM, and healthcare workers represented the high-risk group.
A meta-analysis of proportion was performed using the 'meta' and 'metafor' packages in the statistical program R. Data were transformed using the Freeman-Tukey double arcsine method to account for small proportions. The Dersimonian and Laird method, based on the random-effects model, was used to perform the meta-analysis and summarize data in a forest plot. Confidence-interval (CI) for individual studies proportions were calculated using the Clopper-Pearson method. Heterogeneity was assessed based on the Cochran Q test and quantified by the I
2 index. Heterogeneity was considered significant when the p-value of the Cochran Q test was less than 0.05. The level of heterogeneity was rated as high, medium, or low when the I
2 index was 75%, 50%, and 25%, respectively [
16]. Publication bias was evaluated graphically by a funnel plot of the transformed proportion against the sample size [
17]. We used the Egger test to assess the symmetry of the plot (p < 0.1).
Discussion
We evaluated the seroprevalence of HCV infection in Burkina Faso between 1990 and 2020 in several settings and populations. The reported seroprevalence in low-risk groups was 3.72% (95% CI: 3.20–4.28) and may reflect that of the general population, classifying the country among those with intermediate seroprevalence [
8]. Previous analyses reported a seroprevalence between 4.9 and 6.1% in Burkina Faso, ranking the country among those with the highest seroprevalence in West Africa [
10,
12]. However, these reports included high-risk populations in their estimations. In addition, as HCV seroprevalence decreased over time, the inclusion of more recent studies in our review may explain our lower rate. The rate reported in this review is similar to that of the only nationwide survey conducted in 2010, which found a weighted seroprevalence of 3.6% (95% CI: 3.3–3.8) in the general population [
9].
Although non-significant, a decreasing trend was observed over the past three decades and can be attributed to several factors, including the improvement of transfusion and injection safety. Since 2000, blood transfusion in Burkina Faso is managed by the national center for blood transfusion (CNTS), which has the capacity for infection screening. However, in 2009, its production capacity covered only half of the needs, with the remaining directly collected in the health facilities not supplied by the CNTS. A survey of 42 of these health centers showed that 14.3% were not routinely performing HCV testing [
23]. In addition, a residual risk of HCV transmission persists, estimated at one in 213 donations, as blood screening for HCV is only based on the detection of anti-HCV antibodies [
24,
25]. Therefore, nationwide coverage of the blood supply by the CNTS and nucleic acid testing for HCV is recommended to reduce the risk of transfusion-transmitted hepatitis C.
Improved injection safety is the other factor that could explain the downward trend of infection rates. Indeed, in 1996, it was estimated that 11% of rural and 80% of urban health centers were using new and sterile syringes and needles for injections [
26]. In 2000, a survey of 52 nationally representative health facilities found that this proportion increased to 96%, and no shortage of syringes or needles was reported in those health centers [
27].
The pooled seroprevalence of HCV infection among pregnant women indicates a risk for MTCT, estimated at 4.2–7.8% among viremic women [
28]. Nevertheless, the WHO does not recommend routine testing of pregnant women for HCV infection, as currently there is no treatment to prevent MTCT, and DAAs are not indicated during pregnancy [
2]. Therefore, adequate detection and treatment of childbearing age women during the preconception period could be recommended.
Rural communities were understudied, although they accounted for 73.7% of the latest national population census [
15]. Therefore, the reported seroprevalence may underestimate the magnitude of the actual situation in rural settings. It is thus essential to assess the burden of HCV infection on rural populations, as limited care access, low literacy, and low socioeconomic status are known factors of HCV infection [
4,
29].
Few studies were conducted among key populations for HCV infection. Interestingly, two studies included MSM and one involved sex workers, two hard-to-reach groups. However, no study was conducted among PWID. Evidence exists about injecting drug usage in Burkina Faso, but no data are available on PWID numbers [
30]. Monitoring the extent of injecting drug use and HCV transmission among PWID and other key populations (e.g., MSM and sex workers) should be implemented.
The pooled HCV RNA prevalence among low-risk populations was 1.65% (95% CI: 0.74–2.89%) and may be indicative of the prevalence in the general population. By applying this rate to the total population of the country in 2019 [
15], approximately 301,174 people are estimated to be active HCV carriers in Burkina Faso. The Polaris observatory estimated the total number of active carriers in Burkina Faso at 247,000 in 2015, corresponding to a viremic prevalence of 1.3% (95% CI: 1.0–1.4%), and higher than the global prevalence of 1% [
31]. As HCV infection can be treated with highly effective DAAs, public effort should be undertaken to identify active carriers and link them to care.
Only six studies evaluated HCV genotype distribution, and genotypes 2 and 1 were the most prevalent, as reported by previous publications [
4,
12,
32]. Since the advent of pangenotypic DAAs, genotype determination is considered of little interest in deciding the adequate treatment for chronic HCV [
2,
6]. However, recent reports of treatment failures with pangenotypic DAAs in patients of African descent infected with genotypes 1 and 4 [
33,
34] are alarms for monitoring circulating genotypes and evaluating the effectiveness of HCV treatment.
Our study is limited by the small sample size in rural and high-risk populations and the diversity of anti-HCV antibody measurement methods. Also, as expected from a meta-analysis of prevalence data, significant heterogeneity was observed and could be attributed to the various populations and geographic areas [
13]. These factors may have underestimated or overestimated the actual seroprevalence. Despite these limitations, our results are valuable in guiding public health response in a setting where data on HCV infection in specific populations and settings are scarce.
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