Prevalence and associated risk factors of human leishmaniasis in sub-Saharan Africa: an umbrella review

Abstract

Background

Leishmaniasis is a neglected tropical disease caused by the flagellate protozoa leishmania. Leishmaniasis has spread or reemerged in various countries, causing global health and economic problems. Thus, comprehensive information on the pooled prevalence of human leishmaniasis played an important role in reducing its impact.

Objective

This review aimed to assess the pooled prevalence of human leishmaniasis and associated risk factors.

Methods

A comprehensive search was conducted for potential articles using the Web of Science, PubMed, Science Direct databases, Semantic Scholar, and Google Scholar search. Seven relevant articles about leishmaniasis prevalence and related determinants were found for the final umbrella review. Utilizing Microsoft Excel, data was extracted using separate sheets for leishmaniasis prevalence and related factors. Version 17.0 of the STATA software was used for analyzing the extracted data. The contribution of each research to the final results was ascertained by a sensitivity analysis. Egger’s test and a funnel plot were used to determine publication bias. Inverse of variance statistics were used to check for heterogeneity across studies; major heterogeneity was taken into consideration, and subgroup analysis and meta-regression analysis were used if the I² value was ≥ 50%.

Results

The systematic search yielded 8,534 articles, of which 7 studies were included in this umbrella review. The pooled prevalence of human leishmaniasis in this review was 19.54% (95% CI: 13.78–25.30), indicating significant variation in the prevalence of human leishmaniasis, with I² statistics indicating values more than or equal to 99.96% at P = 0.00. There were significant differences in the pooled prevalence of human leishmaniasis, according to the subgroup analysis based on sample size (P = 0.00). Presence of termite hills (AOR = 4.35, 95% CI:1.06,7.64), presence of domestic animals (AOR = 2.33, 95% CI:2.02,2.64)), past history of leishmaniasis in the family (AOR = 3.51, 95% CI:3.27,3.76), and sleeping under an acacia tree (AOR = 2.03, 95% CI:1.16,2.90) were associated with the pooled prevalence of human leishmaniasis. Moreover, gender, age, family size, farmers, housewives, military personnel, sleeping outside, and the presence of a water source or pathway close to home were some of the risk factors involved in human leishmaniasis.

Conclusions

This umbrella review showed that human leishmaniasis is prevalent in sub-Saharan Africa. The reported increase in the incidence of human leishmaniasis emphasizes the necessity of better monitoring systems and infection control methods to lower the burden and spread of the disease in sub-Saharan Africa. Addressing the causes of human leishmaniasis and lowering its negative effects on public health also requires coordinated actions.

Clinical trial number

Not applicable.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-025-12174-w.

Introduction

Leishmaniasis is a neglected tropical disease (NTD) brought on by the flagellate protozoa Leishmania [1]. It is caused by 20 Leishmania species and spreads by the biting of infected female sandflies, primarily Phlebotomus and Lutzomyia [2, 3]. Leishmaniasis is spread in the Old World by species of the genus Phlebotomus, including Phlebotomus papatasi, P. longipes, P. dubosqi, P. salehi, P. pedifer, P. perniciosus, P. orientalis, and P. sergenti. Additionally, leishmaniasis is spread across the New World by Lutzomyia species such as Lutzomyia longipalpis, L. wellcomei, L. olmeca olmeca, L. flaviscutellata, L. carrerai, L. umbratilis, L. verrucarum, and L. trapidoi. Usually, only one parasite species is spread by each species of sand fly, and each parasite causes a particular disease [4, 5]. Of the approximately 53 species of the Leishmania parasite that have been reported from various parts of the world, 20 are known to be pathogenic to humans, and 31 are known to parasitize animals [6]. Leishmania parasite infections in animal species, especially non-human primates, which may act as disease reservoirs, are referred to as non-human leishmaniasis [7].

Leishmaniasis has a widespread geographical distribution, with prevalence in South Asia, North Africa, the Middle East, Latin America, and the Caribbean [8]. Leishmaniasis has originated or reemerged in numerous geographical locations, raising worldwide health and economic concerns for humans, domestic animals, and wildlife [9]. It is prevalent in 98 countries, with more than 350 million individuals at risk: an estimated 700,000-1.2 million new cases, 600,000 to 1 million additional new cases of cutaneous, 50,000 to 90,000 new cases of visceral leishmaniasis, and around 20,000 to 40,000 fatalities from the illness each year [10, 11].

The millennium declaration, which established the Millennium Development Goals (MDG) for the years 2000–2015, significantly increased awareness of infectious illnesses in the world around the turn of the century. However, throughout the MDG era, NTD received just 0.6% of development aid since they were overshadowed by other illnesses, which led to their continued marginalization in research, finance, and the implementation of global health [12–14]. Unprecedented resource mobilization resulted in tremendous progress on major diseases like malaria and tuberculosis, but not on NTD [15]. This sparked demands that NTD be added to the Sustainable Development Goals (SDG) agenda beyond 2015 [16, 17]. Leishmaniasis is one of the diseases that are now acknowledged by the SDG for health, with goal 3.3 stating that the end of NTD by 2030 would be determined by the number of people requiring interventions against these diseases [18].

The primary causes of the rise in leishmaniasis cases were environmental and/or climate change, poverty, immunodeficiency, sleeping outside the home because of conflict, substandard housing, tourism, migration to endemic areas in search of employment, and a lack or improper use of protection equipment [19–22].

The World Health Organization (WHO) targeted an eradication plan for leishmaniasis in 2005, concentrating on Southeast Asia, and calling for the identification and treatment of every case [23]. Because of this, Southeast Asia has seen notable success in reducing leishmaniasis, while the Americas have reported a higher prevalence, and there is no trustworthy data from Africa to show any patterns [24–26]. Furthermore, focus in the African area is still insufficient even if research on this illness is intense compared to its burden among other infectious diseases [27].

So far, leishmaniasis research has focused on a single or a small number of characteristics and has primarily been undertaken in Leishmania endemic areas. There is also an urgent need for more ambitious research on the clinical, environmental, co-infection, and resistance predictors of Leishmania in endemic area. In contemporary times, leishmaniasis has a larger geographic spread than before; it is nevertheless one of the world’s most neglected illnesses, affecting mostly the poor and developing countries [28].

This study offers fundamental data on leishmaniasis prevalence and related factors that are helpful to program planners, the academic community, service providers, medical professionals, and most importantly, leishmaniasis patients. Prevention and early detection of this fatal, preventable, and curable disease will reduce morbidity [29].

The prevalence of human leishmaniasis in Sub-Saharan Africa has serious health consequences, reflecting a significant public health burden due to its endemic nature. Key risk factors, including gender, age, family size, and outdoor sleeping practices, especially affect vulnerable populations such as farmers and military personnel, exacerbating their susceptibility to the disease [30, 31]. In addition to raising morbidity and death, this high incidence puts pressure on the economy by lowering productivity and raising healthcare expenses, which further impoverishes impacted areas [32]. The aggregated data highlight the urgent need for more intense infection control measures and comprehensive surveillance mechanisms to track epidemics efficiently [33]. Furthermore, a coordinated preventive and eradication strategy at the local, national, and international levels is required to reduce the disease’s public health and economic consequences. Raising community awareness and expanding financing for research and targeted therapies are critical steps toward improving health outcomes and lowering the prevalence of leishmaniasis in the region [34].

Moreover, there are several reasons why a thorough investigation of leishmaniasis prevalence and associated factors in sub-Saharan Africa is crucial. An umbrella review, which combines information from several systematic reviews and meta-analyses, provides a detailed picture of the leishmaniasis situation in sub-Saharan Africa, influencing public health policy, identifying risk factors, enhancing monitoring systems, and guiding research goals. All aspects of human leishmaniasis management, including financing, lobbying, progress tracking, targeted interventions, and resource allocation, depend on accurate epidemiological data on the disease’s burden [35]. There is no available comprehensive evidence on the pooled prevalence of human leishmaniasis in sub-Saharan Africa [36]. So, the purpose of this umbrella review is to summarize the evidence from multiple research syntheses of the prevalence and associated risk factors of human leishmaniasis in sub-Saharan Africa. In this study, we aimed to conduct an umbrella review to determine the pooled prevalence of human leishmaniasis and its associated risk factors in sub-Saharan Africa.

Method

Study protocol and registration

This umbrella review’s protocol (PROSPERO: CRD420250646261) had previously been developed and registered. We conducted comprehensive systematic evaluations of studies describing human leishmaniasis prevalence and its associated risk factors.

Database and search strategy

The protocol was registered on 10/12/2024 and the first search for the umbrella review began on 20/12/2024. Studies published in English and conducted in sub-Saharan African countries until 20/1/2025 were included in this umbrella review. An inclusive literature search was conducted to identify studies about the prevalence and associated risk factors of human leishmaniasis reported among the sub-Saharan African countries’ population of various study subjects. Systematic searches were conducted for both electronic and grey literature. PubMed, Science Direct, Web of science, Semantic Scholar, and Google Scholar were used to retrieve data. Boolean operators like “OR” and “AND” have been used in addition to search terms used alone. An example of keywords used in Google Scholar to select relevant studies was as follows: [“Prevalence” OR “Magnitude” OR “Epidemology” AND “human leishmaniasis” AND “associated factors” OR “risk Factors” AND " Angola” OR “Benin” OR “Botswana” OR “Burkina Faso” OR “Burundi” OR “Cameroon” OR “Cape Verde” OR “Central African Republic” OR “Chad” OR “Comoros” OR “Dem. Rep. of the Congo” OR “Djibouti” OR “Equatorial Guinea” OR “Eritrea” OR “Ethiopia” OR “Gabon” OR “Gambia” OR “Ghana” OR “Guinea” OR “Guinea-Bissau” OR “Ivory Coast” OR “Kenya” OR “Lesotho” OR “Liberia” OR “Madagascar” OR “Malawi” OR “Mali” OR “Mauritania” OR “Mauritius” OR “Mayotte” OR “Mozambique” OR “Namibia” OR “Niger” OR “Nigeria” OR “Republic of the Congo” OR “Reunion” OR “Rwanda” OR “Sao Tome and Principe” OR “Senegal” OR “Seychelles” OR “Sierra Leone” OR “Somalia” OR “South Africa” OR “South Sudan” OR “St. Helena” OR “Swaziland” OR “Tanzania” OR “Togo” OR “Uganda” OR “Zambia” OR “Zimbabwe” OR “sub-Saharan Africa countries " 2014–2025]. Furthermore, a snowball search was performed on the citation lists of the included studies. The researcher incorporated studies recorded from January 01, 2014 until January 20, 2025.

Eligibility criteria

Articles obtained from the abovementioned databases were imported to EndNote version 20 reference managing software (Thomson Reuters, New York, NY). For this umbrella review, the included studies were:1) systematic reviews and meta-analyses of cross-sectional and observational studies that gave a prevalence of human leishmaniasis 2) Articles published in peer-reviewed journals; and 3) articles published in English from 2014 to January 20, 2025. We rejected studies if:1) they had a low quality score according to the mentioned criteria. 2) Case series, letters, comments, and editorials: and/or failed to measure the desired outcome (i.e., prevalence and/or associated risk factors of human leishmaniasis); 3) Studies beyond systematic reviews and meta-analyses were excluded; 4) if they were not provided sufficient data for pooling of prevalence were excluded.

Outcome of interest

The primary outcome of this review was the pooled prevalence of human leishmaniasis in sub-Saharan Africa, along with the associated risk factors, as reported in systematic reviews and meta-analyses. This outcome was expressed both as a percentage and in terms of the number of cases (n) relative to the total number of participants (N). By synthesizing these findings, we aim to provide a comprehensive overview of the disease’s prevalence and the factors contributing to its spread in this region.

Study selection and quality assessment

Each included a systematic review and meta-analysis used the Assessing the Methodological Quality of Systematic Reviews (AMSTAR) tool [37]. Two independent reviewers (W.A. and D.W.) screened the titles identified in the abovementioned databases. Following this, two reviewers (W.A. and D.W.) independently screened eligible studies for the abstract. Finally, full-text screening was conducted by two reviewers (W.A. and S.F.F.). The sixteen critical appraisal checklists were assessed for evaluation of the quality of systematic review articles. This review includes studies having a final quality score of at least 50%.

Data extraction

A standardized data extraction form on Microsoft Excel 2010 was utilized to systematically gather or record relevant information from each included potential study. The extraction process covered various domains, including study characteristics, such as first author, year of publication, study design, number of participants, study area, prevalence, and associated factors of human leishmaniasis in each study. The extracted data were checked by two reviewers (W.A. and D.W.) for accuracy and consistency. The third reviewer (Y.A.D.) was also engaged where necessary.

Statistical analysis

The extracted data were entered into Microsoft Excel and analyzed using STATA version 17 (Stata Corp. Stata Statistical Software. College Station, TX: Stata Corp LP). A random-effects model was used to get an overall summary estimate of the prevalence across studies. Point estimation with a confidence interval of 95% was used. A Sensitivity analysis was conducted to assess the role of each study in the final result by excluding each study one by one, and the presence of publication bias was assessed by visually inspecting funnel plots and Egger’s test. Heterogeneity across studies was checked by inverse of variance (I²) statistics; if the I² value was ≥ 50%, significant heterogeneity was considered. When studies were significantly different (I² ≥ 50%), we explored sources of heterogeneity through subgroup analysis and meta-regression analysis.

Results

Overall, 8,534 relevant articles were found during the initial search. These articles were arranged using citation management software (EndNote X 20) after obtaining them from various databases and search engines. The 4211 articles were excluded due to redundancy. Of the 4323 items examined for title, 4021 were excluded. Furthermore, 176 papers were removed based on their abstracts since they were unrelated to the current review. After a full-text screening, 114 publications from the remaining 121 researches were disqualified since they had no bearing on the current review. After a comprehensive examination utilizing predetermined standards and a quality evaluation, 7 studies were included in the final meta-analysis [19, 36, 38–42]. The included studies were all released between January 01, 2014, and January 20, 2025. A flow diagram elucidating the literature screening process is presented in (Fig. 1).

Fig. 1.

PRISMA flow diagram indicated the results of the search and reasons for exclusion [43]

Characteristics of the included studies

Most systematic review and meta-analysis studies included in this review were cross-sectional in design. Also, they included a total of 132 studies, providing a total sample of 482,097 study participants. The number of studies per systematic review and meta-analysis ranged from 7 (lowest) [42] to 39 (highest) [36]. The sample size per meta-analysis ranged from 2382 (lowest) [39] to 230,960 (highest) [42]. The overall characteristics of the included studies, including the topic they addressed, are shown in (Table 1). As a measure of overlap, we computed the corrected covered area by dividing the frequency of the index publication’s repeated occurrences in other reviews by the product of index publications and reviews, which is then subtracted by the number of index publications. Therefore, the corrected covered area for this review was 1.4%. This determined as follows [44].

Table 1.

Characteristics of the included studies in an umbrella review

Author	Year of publication	Country	Study participants	Sample size	Number of article	Human leishmaniasis prevalence (%)	Quality/16
Abdoulaye et al. [39]	2016	Mali	General Population	2,382	20	22.1	11
Mekonnen et al. [38]	2020	Ethiopia	General Population	50,883	11	9.13	13
Endalew et al. [19]	2022	Ethiopia	General Population	99,226	19	20.4	13
Abebe et al. [36]	2024	East Africa	General population	40,367	39	26.16	14
Ayalew et al. [40]	2018	Ethiopia	General population	50,991	25	21	13
Habtamu et al. [41]	2025	Ethiopia	General population	7,288	11	9.0	14
Musa et al. [42]	2022	Sudan	General population	230,960	7	29	12

Where CCA = Corrected covered area, N = Number of included publications (sum of checked boxes), r = number of rows (primary studies), c = number of columns (number of systematic reviews).

Heterogeneity of included studies

The heterogeneity was assessed for the prevalence of human leishmaniasis. There was significant heterogeneity on the prevalence of human leishmaniasis, with I² statistics showing higher than or equal to 99.96% at P value = 0.00 [19, 36, 38–42].

Publication bias of included studies

A funnel plot was used for assessing potential publication bias in the included studies. Also, an Egger’s test was used to evaluate the potential publication bias in the included studies. The Egger’s test of human leishmaniasis prevalence indicated that there was no publication bias with a p-value = 0.9982 [19, 36, 38–42]. However, the visually inspected funnel plot of human leishmaniasis prevalence indicated that there was publication bias (Fig. 2).

Fig. 2.

Funnel plot for publication bias of studies for pooled prevalence of human leishmaniasis

Sensitivity

In sensitivity analyses utilizing the leave-one-out strategy, eliminating none of the studies had a significant influence on pooled burden estimates and heterogeneity measures within review studies. Therefore, sensitivity analysis employing the random-effects model indicated that no one research altered the overall prevalence of human leishmaniasis (Fig. 3) [19, 36, 38–42].

Fig. 3.

Sensitivity analysis for the pooled prevalence of human leishmaniasis

Pooled prevalence of human leishmaniasis in sub-Saharan Africa

The pooled prevalence of human leishmaniasis was 19.54% (95% CI: 13.78–25.30) [19, 36, 38–42] (Fig. 4). A random-effects model shows the presence of heterogeneity among the included studies that deal with prevalence of human leishmaniasis with a 95% CI (I² = 99.96% and P-value = 0.00). Due to the presence of significant heterogeneity between the included studies, a subgroup analysis was carried out to know the prevalence of human leishmaniasis among review articles.

Fig. 4.

Forest plot for the pooled prevalence of human leishmaniasis

Subgroup analyses of human leishmaniasis in sub-Saharan Africa by publication year, number of studies, and sample size

There was high significant heterogeneity among included studies about the prevalence of human leishmaniasis. Inverse of variance (I²) statistics showed greater than or equal to 99.96% heterogeneity among studies for prevalence of human leishmaniasis. To identify the possible source of heterogeneity, subgroup analysis was performed for prevalence of human leishmaniasis on publication year, number of studies, and number of sample size (Figs. 5 and 6, and 7). Consequently, the analysis showed a significant difference in the frequency of human leishmaniasis among studies on the number of sample sizes (Fig. 6).

Fig. 5.

Subgroup analysis for pooled prevalence of human leishmaniasis based on publication year

Fig. 6.

Subgroup analysis for pooled prevalence of human leishmaniasis based on number of sample size

Fig. 7.

Subgroup analysis for pooled prevalence of human leishmaniasis based on number of studies

Meta-regression analysis

Meta-regression analysis was performed by taking into account the number of studies, sample size, and year of publication in order to determine the cause of heterogeneity in the incidence of human leishmaniasis. However, our findings indicated that the occurrence of heterogeneity was not statistically significant for any of the factors (Table 2).

Table 2.

Meta-regression analysis for the included studies to identify the source(s) of heterogeneity

Variables	Coefficient	Std. error	P value	(95% CI)
Publication year	-0.300914	1.074972	0.780	-2.40782,1.805992
Number of studies	0.2788176	0.2945675	0.344	-0.2985241, 0.8561592
Sample size	0.0000547	0.000037	0.139	-0.0000178, 0.0001272

Systematic review on associated factors of human leishmaniasis

The pooled adjusted odds ratio was determined by analyzing associated variables from two studies. Those who slept beneath an acacia tree, lived with domestic animals, lived close to termite hills, and shared a home with someone who had previously had human leishmaniasis were shown to have a comparable increased risk of contracting leishmaniasis. These factors were statistically significant with human leishmaniasis prevalence (Table 3). According to this review, the prevalence of human leishmaniasis was high in Uganda and Somalia among studies conducted in East Africa [36]. Based on this review, the associated risk factors for human leishmaniasis were identified as independent predictors. Among these associated risk factors, gender, age, family size, presence of termite hill/mound, presence of cattle/domestic animals, farmers, housewives, military personnel, outdoor sleeping, presence of leishmaniasis infected family member/s, and presence of water source/pathway near home were the risk factors, which were associated with human leishmaniasis [19, 36, 38–42].

Table 3.

Summary of the pooled effects of factors associated with human leishmaniasis in sub-Saharan Africa

Variable	Pooled AOR (95% CI)	Heterogeneity (I2, P-value)	Number of Studies	Sample Size
Presence of termite hills	4.35 (1.06,7.64)	99.25%,0.01	2	47,655
Presence of do mestic animals	2.33 (2.02,2.64)	63.89%,0.00	2	47,655
Sleeping under an acacia tree	2.03 (1.16,2.90)	95.30%,0.00	2	47,655
Past history of leishmaniasis in the family	3.51 (3.27,3.76)	33.05%, 0.00	2	47,655

Abbreviation: AOR: Adjusted Odds Ratio, CI: Confidence Interval

Discussion

This umbrella review showed the prevalence and associated risk factors of human leishmaniasis on a period of eleven years in sub-Saharan Africa. In this review, the pooled prevalence of human leishmaniasis was 19.54%. This finding has been supported by a report, which shows that the prevalence of leishmaniasis has more than doubled, from 1,934,553 cases in 1990 to 4,166,621 in 2017, with 0.9–1.6 million new cases occurring globally each year [45]. Also, these results are corroborated by earlier research indicating that leishmaniasis is most prevalent in the Horn of Africa, with northern Ethiopian regions closest to the Sudanese border being the most impacted [46, 47]. This might be due to poor vector management, lack of vaccines availability, and restricted access to novel medications. Others speculate that the lack of progress in leishmaniasis diagnosis and treatments, migration and war, or the cost of the most recent advances in technology like vaccine, treatment, and diagnostics to eradicate the disease might be the cause of this trend [47–49].

Conversely, this finding was lower than that reported in Latin America (38.8%) [50], Pakistan (56%) [51] and Iraq [48.23%, 51.65%] [52]. This could be due to large population expansion, the prevalence of vectors, climatic temperature, and humidity conditions, which all contribute to this enormous increase in diseases [53]. Also, variations in human activity, such as urbanization, migration, and agricultural methods, can also have a considerable impact on transmission dynamics. Likewise, the methods utilized for diagnosis may contribute to disparities in reported prevalence. since various studies may employ different methods with their own sensitivity and specificity, which results in variable detection rates. Furthermore, factors such as sample size and participant selection might influence the findings’ representativeness; smaller or biased samples may not accurately reflect the larger population. Similarly, seasonal fluctuations, temporal changes in infection rates, the presence of undetectable diseases, health infrastructure, and access to medical treatment can all contribute to variations in reported cases. Also, differences in the parasite’s animal reservoirs can cause disparities in prevalence among locations. Understanding these difficulties is critical for accurately assessing leishmaniasis epidemiology and implementing effective public health interventions [54].

However, this finding was higher than that reported in Iran [2%] [55], in the World [2.3%, 7%, 11.2%] [56–58], Ethiopia (4.0%) [59], and Middle East [12%] [60]. This might be due to differences in methodology and diagnostic techiques, since some may utilize more sensitive or specialized testing that can detect instances overlooked by simpler approaches. Also, environmental and ecological conditions, such as the existence of adequate sandfly vectors and animal reservoirs, might lead to possible increases in transmission rates that are not completely accounted for in studies. Migration, urbanization, and land use changes can introduce more people into regions where the parasite is endemic, raising the risk of exposure and infection. Moreover, socioeconomic barriers, such as restricted access to healthcare and inadequate public health infrastructure, might impede correct reporting and efficient case management. Collectively, these components may indicate that true prevalence rates are much greater than those reported in various studies, emphasizing the need for better surveillance and diagnosis in impacted areas [61].

This review found high heterogeneity in the prevalence of human leishmaniasis among studies. This high heterogeneity in the prevalence of human leishmaniasis among studies can be associated with a number of interrelated factors. Geographical variation has significance because changes in ecosystems, climate, and habitat influence the distribution of sandfly vectors, which are essential for transmission. Furthermore, study methodologies might cause disparities; for example, differences in sampling techniques and diagnostic criteria, whether instances are clinically diagnosed or laboratory confirmed can result in differing prevalence rates. Also population features, such as demography and immunological factors, also contribute to this heterogeneity, since certain populations may be more vulnerable to infection. Additionally, environmental factors, such as urbanization and climate change, can affect vector habitats and human exposure patterns. Similarly, temporal variables, such as changes in epidemiological patterns and public health interventions, can also have an impact on reported prevalence. Moreover, cultural practice and socioeconomic factors, such as access to healthcare and local habits, have a considerable influence on both vector exposure and case detection.The high I² values highlight the need for a comprehensive study to identify the root causes of these disparities and improve public health interventions [62, 63].

Likewise, this review showed that significant difference in the prevalence of human leishmaniasis among studies on the number of sample sizes. Larger sample sizes produce more trustworthy estimates of disease prevalence because they capture a more complete representation of the population, lowering the influence of random fluctuation and boosting the statistical power of the findings. Studies with lower sample sizes, on the other hand, may be more prone to biases and may not reflect the real frequency of leishmaniasis, resulting in either underreporting or overreporting. This change in sample size can also have an impact on the diagnosis of asymptomatic infections, which are frequent in leishmaniasis and may go undetected in smaller cohorts. The discrepancies reported in this analysis underline the vital need for proper sample sizes in epidemiological research to guarantee that prevalence estimates are reliable and generalizable. Ultimately, these findings call for more coordinated efforts to develop research with bigger cohorts to better understand the dynamics of leishmaniasis and to influence effective public health policies [64].

In this review, there is a difference between the funnel plot, which shows publication bias, and Egger’s test, which reveals no bias. The difference between the funnel plot and Egger’s test necessitates careful evaluation of numerous possible explanations for the contradiction. The funnel plot is a visual tool that can highlight asymmetry, which is frequently related with publication bias. However, its interpretation is subjective and impacted by the number of studies included; lower sample sizes may not offer a clear picture. In contrast, Egger’s test is a statistical tool for assessing bias, but it may be insensitive in identifying small biases, particularly in studies with insufficient data. Furthermore, the type of the studies included in the analysis may add to the contradiction; differences in research quality, methodology, and sample sizes can all influence the outcomes of both assessment methods.

According to this review, there were several risk factors that were related to the prevalence of leishmaniasis. This finding was similar to studies that reported associated risk factors of leishmaniasis prevalence [9, 21, 65]. In this review, presence of termite hills was significantly associated with prevalence of human leishmaniasis. This finding is similar with the studies conducted in Ethiopia [66, 67]. This association might be due to termite hills providing ideal microhabitats for sandflies. These structures can boost local biodiversity, perhaps boosting the number of sandflies and Leishmania parasite reservoirs. As a result, locations with termite hills may have greater transmission rates of leishmaniasis, emphasizing the necessity of taking environmental variables into public health initiatives aimed at managing this vector-borne disease.

In this review, presence of domestic animals was significantly associated with prevalence of human leishmaniasis. This finding is comparable with the study conducted in Ethiopia [67], America [68], and India [69]. The relationship may exist because domestic animals can act as reservoirs for the parasites that cause leishmaniasis, allowing the illness to spread through sandfly vectors. Additionally, being near to these animals may increase human exposure to sandfly bites. These findings emphasize the necessity of include animal management and control measures in public health initiatives to lower the risk of leishmaniasis transmission, particularly in places where both domestic animals and the disease are common [70].

In this review, sleeping under an acacia tree was significantly associated with prevalence of human leishmaniasis. This finding is supported by the study conducted in Ethiopia [67]. This association may be due to the ecological importance of acacia trees, which can offer a suitable home for sandflies. As a result, those who sleep outside under these trees may be more exposed to sandfly bites, increasing their risk of illness. These findings highlight the need of public health awareness and prevention actions in endemic regions [71].

In this study, past history of leishmaniasis in the family was significantly associated with prevalence of human leishmaniasis. This finding is in agreement with the study conducted in America [68]. This implies that a genetic vulnerability may make family members more vulnerable to infection. Living in sand fly-infested areas, for example, raises the chance of exposure. Furthermore, familial behaviors and health-seeking habits might impact the risk of infection. Furthermore, a history of leishmaniasis may imply continuing local transmission dynamics, in which the existence of infected vectors or reservoirs continues the disease cycle within the family. This showed that a multimodal strategy that includes education, community engagement, encouraging safe practices, allocating resources strategically, evidence based policies, bed nets, insecticides, controlling reservoirs, environmental management, and focused interventions can result in long term decreases in the burden and transmission of leishmaniasis and ultimately save lives [9].

A tailored and comprehensive approach must be taken to effectively combat leishmaniasis in sub-Saharan Africa. This involves using Integrated Vector Management to reduce sand fly populations through biological methods and improved drainage. Community participation is essential; educating residents about transmission and prevention promotes ownership and sustainability. Investing in affordable rapid diagnostic tests for remote areas and training healthcare professionals can improve case detection and treatment timeliness. Health systems must be strengthened by improved supply chains and provider training in order to ensure that effective treatments are delivered. Specific interventions will be guided by studies on local epidemiology, and the establishment of strong monitoring systems will keep an eye on leishmaniasis cases and vector populations. Increased funding for control programs and multi-sectoral cooperation are required to align national health policies with Sustainable Development Goal 3.3, which calls for the eradication of NTDs by 2030.

The strengths of this review include, to the best of our knowledge, that it is the first umbrella review on leishmaniasis in sub-Saharan Africa, along with rigorous adherence to PRISMA guidelines and the inclusion of sensitivity analysis.We used a predetermined data abstraction methodology and search technique. We used generally recognized techniques for assessing the quality of individual research and critically analyzing them.

The limitations of this review include the fact that all the studies included were published in English, which suggests the possibility of language bias.The inclusion of solely English-language study that may introduces a major language bias, which can influence the findings in a variety of ways. This drawback may result in the exclusion of significant studies published in other languages, notably in leishmaniasis-endemic countries such as portions of Africa. As a result, critical data and insights from these researches may be ignored, resulting in a limited understanding of the disease’s epidemiology, transmission dynamics, and treatment outcomes. Furthermore, the variety of viewpoints and research methodologies used may be impacted by language bias. Studies carried out in various cultural and healthcare settings may provide special perspectives on regional customs, risk factors, and public health strategies that are not included in the literature written in English. This lack of diversity might restrict the application of suggestions across various groups and result in a limited interpretation of findings.

Also, the very limited number of reviewed articles in this umbrella review may have an impact on the overall proportion estimate. The inclusion of small number of studies, together with their unequal distribution, considerably reduces the validity of pooled findings in various ways. A small sample size diminishes statistical power, making it difficult to identify actual effects or association, thus leading to incorrect results that may not represent the larger population. The small number of studies limits the capacity to conduct meaningful subgroup analysis, hindering the investigation of significant changes linked to characteristics such as area, age, or co-morbidities. In addition, the uneven distribution of studies around the country may have an influence on the results of the study. The geographic bias found in the included studies, which mostly focus on Ethiopia and Sudan, significantly limits the findings’ generalizability in Sub-Saharan Africa. This focus on specific countries may obscure the different epidemiological, environmental, and socioeconomic circumstances found in other parts of the continent. As a result, the frequency and transmission dynamics of diseases such as leishmaniasis can vary greatly between nations, depending on local vector populations, climatic conditions, and public health infrastructure. This bias has significant implications for interpreting study findings and developing effective solutions. Policies and initiatives developed from research predominantly focused on Ethiopian and Sudanese data may be inapplicable or ineffective in other Sub-Saharan African countries where disease landscapes differ dramatically. Furthermore, a lack of representation might impede attempts to properly allocate resources and execute targeted public health initiatives in areas that may be equally or more impacted by leishmaniasis but are underrepresented in the research. To alleviate this regional bias, future research should cover a larger range of sub-Saharan African nations, ensuring that findings are more representative and relevant throughout the continent.

Conclusion and recommendation

This review’s findings on human leishmaniasis prevalence in sub-Saharan Africa revealed a high pooled prevalence of human leishmaniasis, indicating a significant difficulty in treating leishmaniasis parasite infections. This means that leishmaniasis infection is still endemic and highly prevalent in sub-Saharan Africa. According to this review, a variety of factors influence the frequency of human leishmaniasis. The observed rise in human leishmaniasis incidence highlights the requirement for improved infection control strategies and surveillance systems for limiting leishmaniasis transmission in sub-Saharan Africa. Moreover, collaboration at the local, national, and international levels is required to address the factors that trigger human leishmaniasis and mitigate its public health and socioeconomic impacts.

Supplementary Information

Below is the link to the electronic supplementary material.

Abbreviations

MDG

Millennium Development Goals

NTD

Neglected Tropical Disease

SDG

Sustainable Development Goals

WHO

World Health Organizations

Author contributions

**W.A.** led the umbrella review, article selection, data mining, data screening, data extraction, statistical analysis, manuscript preparation, and overseeing the study’s conceptualization. **W.A., D.W.,** and **Y.A.D.** involved in data mining, data extraction, manuscript writing, editing, and ensuring accuracy and completeness. **Y.A.D.** and **S.F.F.** were involved in statistical analysis consultation of the overall process of this review. Moreover, all authors actively engaged in critically reviewing the study’s progress, data analysis, and manuscript preparation, involved in the approval of the final manuscript for submission, thereby affirming their endorsement of its content and findings.

Funding

This umbrella review was not supported by any organization or individual.

Data availability

Data supporting the study’s findings found in the manuscript.

Declarations

Ethics approval and consent to participate

Not applicable to this umbrella review.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.