Current Understanding of Meningitis Pathogens, Immunity Gap, and Future Prevention Strategies in Sri Lanka: A Narrative Review.

Meningitis, an acute and life-threatening inflammation of the protective membranes covering the brain and spinal cord caused primarily by bacterial, viral, fungal, or parasitic infections, remains a major global health challenge, causing significant morbidity and mortality, particularly among children and vulnerable populations. The Sri Lankan epidemiological unit reported approximately 1000-1500 meningitis cases annually. This review summarizes current knowledge on meningitis in Sri Lanka, drawing on global evidence and locally published studies to examine epidemiology, clinical presentation, diagnostic approaches, immunity gap, and future priorities. Most studies indicate that bacterial meningitis, particularly caused by Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae, remains the most severe and clinically significant form. Viral etiologies, especially enteroviruses, are also commonly reported. Although the introduction of the H. influenzae Type b (Hib) vaccine has significantly reduced disease burden, important immunity gaps persist due to limited pneumococcus serotype coverage and the absence of routine meningococcal vaccination. Diagnostic challenges, including delays in cerebrospinal fluid collection, limited access to molecular testing, and preanalytical errors, hinder early detection and accurate pathogen identification. Future directions should focus on strengthening molecular diagnostic capacity, strengthening point-of-care rapid antigen assays and decentralized molecular diagnostics, expanding serotype surveillance, improving sample collection practices, and evaluating the feasibility of introducing meningococcal vaccination into the national immunization schedule. Bridging these gaps is essential for aligning Sri Lanka's efforts with global targets outlined in the World Health Organization's (WHO) Defeating Meningitis by 2030 roadmap.