Global burden of asymptomatic malaria among blood donors: systematic review and meta-analysis

Malaria is a significant public health concern, particularly in endemic regions. Asymptomatic blood donors pose a risk for transfusion-transmitted malaria, especially in regions with limited donor screening. This systematic review and meta-analysis aim to estimate the updated worldwide pooled prevalence of asymptomatic malaria among blood donors and assess the variation in pooled prevalence by region and diagnostic methods used. A systematic literature search was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. The literature search was conducted using multiple electronic databases, including PubMed, Scopus, Web of Science, ScienceDirect, EMBASE, African Journal Online (AJOL), and Google Scholar, covering the period from January 2018 to May 2025. Eligible studies were screened based on pre-specified inclusion criteria. Studies were managed by EndNote 20, data were extracted by using Microsoft Excel 2013, and statistical analysis was done by using STATA version 11. Sub-group analyses were performed based on continents, lab diagnostic methods, and year of study. Due to the presence of heterogeneity random effect model was used. Publication bias was assessed statistically by Egger’s test and graphically through a funnel plot. In this systematic review and meta-analysis, a total of 17,627 records were retrieved through the database search, of which 15 articles met the eligibility criteria from Africa, Asia, and South America to determine the pooled prevalence of asymptomatic malaria among blood donors. The pooled prevalence of malaria among blood donors was 0.32% (95% CI: 0.25-0.39), and heterogeneity value I2 = 99.2%. The sub group analysis showed that highest prevalence was recorded in the African continent at 15.89% (95% CI: 9.48-22.31), with a heterogeneity value I2 = 99.5% followed by South America at 0.79% (95% CI: 0.30-1.89), with a heterogeneity value I2 = 99.3%, and the lowest prevalence was in the Asian continent 0.21% (95% CI: 0.15-0.27), with a heterogeneity value I2 = 52.2%. The pooled prevalence of asymptomatic malaria among blood donors in terms of diagnostic tests used was, microscopy 21.86% (95% CI: 6.96-36.76), rapid diagnostic test 0.21% (95% CI: 0.153-0.267), and 5.03% (1.12-8.94) using polymerase chain reaction. The current systematic review and meta-analysis highlight the global prevalence of asymptomatic malaria among blood donors, showing significant regional variations and identifying high-risk areas that pose a serious threat to transfusion safety. Despite limitations such as high heterogeneity and publication bias, the result underscores the need for targeted screening and preventive strategies, particularly in the African region, to enhance blood safety. The result highlights the urgent need for region-specific screening strategies and improved diagnostic approaches to ensure blood transfusion safety.