Flashtalk 25th International Pathogenic Neisseria Conference 2026

Serogroup dynamics and age-specific burden of Neisseria meningitidis in Nigeria: multi-state molecular surveillance data, 2025. (#078)

Ikechukwu Nnaji 1 2 , Abiodun Egwuenu 3 , Michael O Popoola 2 , Chidiebere E Opara 4 , Charles C Korie 2 , Iliya D Cheshi 5 , Eme Ekeng 4 , Deborah C Effiong 2 , Zayyanatu Nuru 2 , Chinonso C Onyemuze 2 , MacDonald S Maduabuchi 6 , Stanley U Ogbonna 2 , Chiamaka M Ugwumba 4 , Hamidah Haroon 2 , Osaoghomwen Amiebenomo 4 , Bassey Akiba 2 , Joy M Ajodo 2 , Amos Dangana 2 , James Avong 2 , Olajumoke Babatunde 2 , Emmanuel I Eze 3
  1. School of Public Health , Miva Open University, Abuja, Federal Capital Territory, Nigeria
  2. NCDC National Reference laboratory, Nigeria Centre for Disease Control and Prevention, Abuja, Federal Capital Territory, Nigeria
  3. Planning, Research and Statistics, Nigeria Centre for Disease Control and Prevention, Abuja, Federal Capital Territory, Nigeria
  4. NCDC National Reference laboratory, Nigeria Centre for Disease Control and Prevention, Abuja, Federal Capital Territory, Nigeria
  5. Surveillance and Epidemiology, Nigeria Centre for Disease Control and Prevention, Abuja, Federal Capital Territory, Nigeria
  6. Medical Laboratory Sciences, University of Nigeria , Nsukka, Enugu, Nigeria

Introduction

Cerebrospinal meningitis remains a major public health threat across the African meningitis belt, where Neisseria meningitidis (Nm) causes recurrent outbreaks. In Nigeria, changing serogroup distribution and diverse geographic transmission patterns create persistent challenges for controlling outbreaks and implementing effective vaccination campaigns. We analyzed our laboratory data to characterize serogroup dynamics, geographic spread, and age-specific burden in 2025.

Methods

A total of 700 (421 males and 279 females) cerebrospinal fluid samples from suspected meningitis cases across 19 affected states were tested for Nm confirmation and serogrouping at the NCDC National Reference Laboratory in 2025 using real-time polymerase chain reaction (qPCR). Demographic and geographic data captured in case investigation forms were analyzed descriptively together with corresponding laboratory results to characterize epidemiological patterns of transmission across states and age groups.

Results

Of the samples tested, 34.1% (239/700) were confirmed positive for Nm, with 64.9% males(155/239) and 35.1% females(84/239). SerogroupC (NmC) was predominant (60.7%), followed by serogroupW (NmW) (36.4%) and serogroupX (2.9%). Transmission was widespread across northern Nigeria, particularly within the meningitis belt. The highest burden was seen in Sokoto (65 cases), Yobe(38), and Gombe (37), followed by Kebbi (29), Jigawa (21), Katsina (20), Adamawa (13), Borno (6), Plateau (5), Bauchi (3), Niger (1), and Zamfara (1), with multiple local government areas affected. Age distribution in years revealed a marked concentration among younger populations: 0-9 (88 cases), 10-19 (116), and 20-29 (25), accounting for 95.4% of cases. The highest burden was observed in the 10-19 age group (48.5%), followed by 0-9 (36.4%) and 20-29 (10.5%), with minimal contribution from older age groups: 30-39 (3 cases), 40-49 (4), 50-59 (3), and 60-69 (1). Serogroup patterns varied by age, with NmW predominant in 0-9 (59%), while NmC dominated older age groups, particularly 10-19 (74%).

Conclusion

Our study highlights the predominance of serogroup C alongside continued circulation of serogroup W, with a pronounced burden among children and adolescents. The widespread multi-state transmission underscores the need for strengthened molecular surveillance and age-targeted vaccination strategies. Continuous monitoring of serogroup dynamics is critical to inform effective meningococcal control policies and public health interventions in Nigeria and the broader meningitis belt.