Etiology of Bacterial Meningitis Among Children <5 Years Old in Côte d'Ivoire: Findings of Hospital-based Surveillance Before and After Pneumococcal Conjugate Vaccine Introduction

Abstract

Background: Bacterial meningitis remains a major disease affecting children in Côte d'Ivoire. Thus, with support from the World Health Organization (WHO), Côte d'Ivoire has implemented pediatric bacterial meningitis (PBM) surveillance at 2 sentinel hospitals in Abidjan, targeting the main causes of PBM: Streptococcus pneumoniae (pneumococcus), Haemophilus influenzae, and Neisseria meningitidis (meningococcus). Herein we describe the epidemiological characteristics of PBM observed in Côte d'Ivoire during 2010-2016.

Methods: Cerebrospinal fluid (CSF) was collected from children aged <5 years admitted to the Abobo General Hospital or University Hospital Center Yopougon with suspected meningitis. Microbiology and polymerase chain reaction (PCR) techniques were used to detect the presence of pathogens in CSF. Where possible, serotyping/grouping was performed to determine the specific causative agents.

Results: Overall, 2762 cases of suspected meningitis were reported, with CSF from 39.2% (1083/2762) of patients analyzed at the WHO regional reference laboratory in The Gambia. In total, 82 (3.0% [82/2762]) CSF samples were positive for bacterial meningitis. Pneumococcus was the main pathogen responsible for PBM, accounting for 69.5% (52/82) of positive cases. Pneumococcal conjugate vaccine serotypes 5, 18C, 19F, and 6A/B were identified post-vaccine introduction. Emergence of H. influenzae nontypeable meningitis was observed after H. influenzae type b vaccine introduction.

Conclusions: Despite widespread use and high coverage of conjugate vaccines, pneumococcal vaccine serotypes and H. influenzae type b remain associated with bacterial meningitis among children aged <5 years in Côte d'Ivoire. This reinforces the need for enhanced surveillance for vaccine-preventable diseases to determine the prevalence of bacterial meningitis and vaccine impact across the country.

Keywords: Haemophilus influenzae; Côte d’Ivoire; meningitis; pediatric; pneumococcus.

Figure 1.

A breakdown of the suspected pediatric bacterial meningitis cases during surveillance in Côte d’Ivoire, 2010–2016. A total of 2762 cerebrospinal fluid (CSF) samples were collected from patients with suspected pediatric bacterial meningitis admitted to 2 sentinel hospitals within Abidjan. Diagnostic tests were performed for most CSF samples at the sentinel hospitals, and 1160 CSF samples were sent to the World Health Organization regional reference laboratory (Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine) for confirmatory species-specific polymerase chain reaction. Abbreviations: CSF, cerebrospinal fluid; IBD, invasive bacterial disease; PCR, polymerase chain reaction; RRL, regional reference laboratory.

Figure 2.

The distribution of confirmed pediatric bacterial meningitis cases within 2 sentinel hospitals in Côte d’Ivoire, 2010–2016. The number of cerebrospinal fluid samples that were positive for Streptococcus pneumoniae, Neisseria meningitidis, or Haemophilus influenzae during each year of surveillance in Côte d’Ivoire are shown. Light gray shading indicates meningitis cases that were caused by bacterial serotype/groups targeted by the meningococcal conjugate vaccines (MenAfriVac, the 13-valent pneumococcal conjugate vaccine [PCV13], and the H. influenzae type b [Hib] vaccine). Dark gray shading highlights cases of H. influenzae meningitis identified as non–type b, and white shading indicates cases of pneumococcal meningitis caused by serotypes not targeted by PCV13.