Neisseria Meningitidis Carriage Among Hajj and Umrah Pilgrims: A Systematic Review and Meta-Analysis

Background: Meningococcal meningitis (MM), which is caused by the bacterium Neisseria meningitidis, represents a considerable public health concern during the Hajj and Umrah pilgrimages. The mass gathering and close quarters associated with these events create an environment that enhances the transmission of this potentially life-threatening infection. Despite mandatory vaccination policies, concerns persist regarding carriage rates and the potential for outbreaks, which are heightened by several factors. This systematic review and single-arm meta-analysis aimed to evaluate the carriage of Neisseria meningitidis (NM) and its vaccination status among pilgrims. Method(s): A systematic review and meta-analysis were conducted according to PRISMA guidelines, focusing on Muslim pilgrims of any nationality who participated in the mass gatherings of Hajj or Umrah in Makkah, Saudi Arabia. We performed a comprehensive search of four electronic databases (PubMed, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials) from their inception to April 2024. Eligible studies reported on N. meningitidis carriage prevalence, serogroups, and vaccination status among Hajj and Umrah pilgrims. The primary outcome measured was the overall carriage prevalence of Neisseria meningitidis, as determined by the time of assessment. Data were synthesized using random-effects models. Result(s): Out of the 417 studies initially screened, 21 studies (23,552 participants) were included in the systematic review; while the meta-analysis consisted of nine studies. The carriage prevalence of NM before Hajj was 1.6%, increasing to 3.4% after Hajj. Prior to Hajj, the estimate of serogroup A and W was recorded at 0.003 (95% CI [-0.001, 0.006]) and 0.068; (95% CI [-0.14, 0.15]), respectively. Following Hajj, the estimate shifted to 0.001 (95% CI [0.000, 0.002]) for serogroup A and 0.072; 95% CI [0.037, 0.108]) for serogroup W. Vaccination status varied, with gaps among domestic pilgrims, along with the presence of ciprofloxacin resistance in certain strains. Conclusion(s): Saudi Arabia's commendable and sustained commitment to proactive prevention strategies during Hajj and Umrah has reduced Neisseria meningitis cases. Nonetheless, carriage variability and rising antimicrobial resistance of Neisseria meningitidis highlight the need for enhanced surveillance and alternative prophylaxis strategies for high-risk populations. The findings of this study remain inconclusive due to significant heterogeneity and underscore the need for comprehensive and well-structured primary studies to gather strong evidence. Copyright © The Author(s) 2025.