Pediatric Bacterial Meningitis Surveillance in Nigeria From 2010 to 2016, Prior to and During the Phased Introduction of the 10-Valent Pneumococcal Conjugate Vaccine

Abstract

Background: Historically, Nigeria has experienced large bacterial meningitis outbreaks with high mortality in children. Streptococcus pneumoniae (pneumococcus), Neisseria meningitidis (meningococcus), and Haemophilus influenzae are major causes of this invasive disease. In collaboration with the World Health Organization, we conducted longitudinal surveillance in sentinel hospitals within Nigeria to establish the burden of pediatric bacterial meningitis (PBM).

Methods: From 2010 to 2016, cerebrospinal fluid was collected from children <5 years of age, admitted to 5 sentinel hospitals in 5 Nigerian states. Microbiological and latex agglutination techniques were performed to detect the presence of pneumococcus, meningococcus, and H. influenzae. Species-specific polymerase chain reaction and serotyping/grouping were conducted to determine specific causative agents of PBM.

Results: A total of 5134 children with suspected meningitis were enrolled at the participating hospitals; of these 153 (2.9%) were confirmed PBM cases. The mortality rate for those infected was 15.0% (23/153). The dominant pathogen was pneumococcus (46.4%: 71/153) followed by meningococcus (34.6%: 53/153) and H. influenzae (19.0%: 29/153). Nearly half the pneumococcal meningitis cases successfully serotyped (46.4%: 13/28) were caused by serotypes that are included in the 10-valent pneumococcal conjugate vaccine. The most prevalent meningococcal and H. influenzae strains were serogroup W and serotype b, respectively.

Conclusions: Vaccine-type bacterial meningitis continues to be common among children <5 years in Nigeria. Challenges with vaccine introduction and coverage may explain some of these finding. Continued surveillance is needed to determine the distribution of serotypes/groups of meningeal pathogens across Nigeria and help inform and sustain vaccination policies in the country.

Keywords: Nigeria; meningitis; meningococcus; neumococcus; pediatric.

Figure 1.

Distribution of suspected pediatric bacterial meningitis cases from 2010 to 2016 within 5 sentinel hospitals in 5 Nigerian states. A total of 5134 suspected pediatric bacterial meningitis cases were observed at 5 sentinel hospitals: Lagos University Teaching Hospital (Lagos State), University of Nigeria Teaching Hospital (Enugu State), Abubakar Tafawa Balewa University Teaching Hospital (Bauchi State), University of Ilorin Teaching Hospital (Kwara State), and University of Benin Teaching Hospital (Edo State). Each hospital commenced surveillance at different time points; however, surveillance continued for all hospitals until 2016. The number of suspected cases of bacterial meningitis and the number of confirmed cases of meningitis (World Health Organization definitions [16]) varied per hospital. The main causative agents for bacterial meningitis were Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae.

Figure 2.

Proportion of confirmed pediatric bacterial meningitis cases and the pathogens responsible from 2010 to 2016 in 5 Nigerian states. The percentage of confirmed bacterial meningitis cases caused by Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae in children <5 years across 5 Nigerian states. A dashed black line indicates the total number of cerebrospinal fluid samples that were tested each year of surveillance.

Figure 3.

Monthly distribution of suspected pediatric bacterial meningitis cases for the period 2010 to 2016 within 5 sentinel hospitals across Nigeria. The percentage of pediatric bacterial meningitis (PBM) cases seen across 5 hospitals in 5 Nigerian states, caused by Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae per month. A black dashed line indicates the total number of PBM cases per month throughout the surveillance period.