Emergence of Neisseria meningitidis serogroup X in the 2017/2018 Cerebrospinal Meningitis outbreak, Nigeria

Background: Outbreaks of meningitis occur periodically in Nigeria, with the northern parts mostly affected. Neisseria meningitidis is the commonest cause of meningitis outbreaks; Streptococcus pneumoniae and Haemophilus influenzae causes. Following a large outbreak in 2016/2017, another outbreak occurred in 2017/2018, with Neisseria meningitis C being the cause. This study is aimed at characterizing Neisseria meningitidis strains using genotypic technique (PCR) and bringing to limelight the need for continued surveillance, especially with the emergence of Neisseria meningitidis serogroup X, which like serogroup C, is also capable of causing epidemics. Methods and materials: We conducted active surveillance of suspected meningitis cases that met the WHO case definition in states that reported cases of meningitis between November 2017 and June 2018. CSF was collected from suspected meningitis cases and aliquots sent to the National Reference Laboratory, Abuja from States that reported cases and analysed by culture, Rapid Diagnostic Test (Pastorex®) and Polymerase Chain Reaction for detection of N. meningitidis, S. pneumoniae and H. influenzae. Results: 548 samples were analysed by PCR to detect sodC, lytA and hpd genes. Neisseria meningitidis (n = 236, 43.1.0%; NmC = 182, 33.2%, NmX = 43, 8.0%. others = 11, 2.0%) was the predominant cause of meningitis followed by S. pneumoniae (n = 22, 4.0%) and Haemophilus influenzae (n = 26, 4.7%). Conclusion: This study detected an unusual serogroup of Nm, although outbreaks of meningitis in Nigeria have previously been caused by NmA and NmC. Our data underscores the urgent need for ongoing bio surveillance. The increasing incidence of Neisseria meningitidis X is worrisome, because the reactive and preventive vaccination for meningitis does not cover this serogroup, countries in the African meningitis belt must prepare to face this potential new challenge. Information has been shared with the Nigeria Centre for Disease Control and WHO for further action.

Abstract licence: CC BY-NC-ND

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