Epidemiology of Bacterial Meningitis in the Nine Years Since Meningococcal Serogroup A Conjugate Vaccine Introduction, Niger, 2010-2018

Meningitis in Niger Republic amidst COVID-19: current issues and novel recommendations

Amidst coronavirus disease 2019 (COVID-19), there has been a misplaced priority on meningitis in the Niger Republic, thus refocusing resources and attention away from the continuing meningitis campaign in the Niger Republic. The over-strained state of public health resources and staff has also led to decreased surveillance, postponed diagnoses, and constrained immunization efforts in Niger Republic. This review aims to bridge the gaps regarding meningitis amid COVID-19 in Niger Republic and offer recommendations to government to mitigate meningitis in the country, with the hope of finding a permanent solution to this debilitating disease. The authors reviewed 45 past and present pieces of literature on meningitis and COVID-19 from 2013 to 2023 in well-renowned scientific databases such as PubMed, ResearchGate, Google Scholar, African Journals Online, Medline, and Embase. Since 2015, Niger Republic has experienced multiple meningitis epidemics that have resulted in 20, 789 cases and 1, 369 deaths [a case fatality rate (CFR) of 6.6%]. A total of 231 cases of meningitis were reported from 1 November 2021 to 31 January 2022. And recently, 559 cases of meningitis (of which 111 are laboratory confirmed), including 18 deaths (overall CFR 3.2%), occurred in the Zinder region, southeast of Niger Republic, from 1 November 2022 to 27 January 2023. Meningitis remains a public health concern in the world, especially in Niger Republic, which could lead to serious long-term complications. Therefore, adequate and novel measures and therapeutic actions should be implemented by the Niger Government to lessen the burden of the disease in the country.

Trends in Neisseria meningitidis serogroups amongst patients with suspected cerebrospinal meningitis in the meningitis belt of Ghana: a 5-year retrospective study

BACKGROUND

Serogroup A Neisseria meningitidis was the major cause of meningococcal meningitis epidemics in the African meningitis belt before 2010 when the monovalent meningococcal A conjugate vaccine (MenAfriVac) was introduced in the region. Therefore, this study aimed to establish the trends in N. meningitidis serogroups from 2016 to 2020 in Ghana's meningitis belt.

METHODS

Polymerase chain reaction (PCR) confirmed laboratory results of suspected cases of cerebrospinal meningitis from January, 2016 to March, 2020 were obtained from the Tamale Public Health Laboratory. The data were subjected to trend analysis using Statistical Package for the Social Sciences version 25. Differences between discrete variables were analyzed using the Cochran-Armitage trend test.

RESULTS

Of the 2,426 suspected cases, 395 (16.3%) were confirmed positive for N. meningitidis using PCR. Serogroup X showed a significant upward trend (P < 0.01), and serogroup W showed a downward trend (P < 0.01). However, no significant trend was observed for any other serogroup.

CONCLUSION

This study showed the emergence of serogroup X, a non-vaccine type, as the predominant N. meningitidis serogroup in the wake of a declining serogroup W in Ghana's meningitis belt.

Childhood meningitis in rural Gambia: 10 years of population-based surveillance

Background

The introduction in many countries of conjugate vaccines against Haemophilus influenzae type b, Streptococcus pneumoniae, and Neisseria meningitidis has led to significant reductions in acute bacterial meningitis (ABM) in children. However, recent population-based data on ABM in sub-Saharan Africa are limited.

Methods

Population-based surveillance for meningitis was carried out in a rural area of The Gambia under demographic surveillance from 2008 to 2017, using standardised criteria for referral, diagnosis and investigation. We calculated incidence using population denominators.

Results

We diagnosed 1,666 patients with suspected meningitis and collected cerebrospinal fluid (n = 1,121) and/or blood (n = 1,070) from 1,427 (88%) of cases. We identified 169 cases of ABM, 209 cases of suspected non-bacterial meningitis (SNBM) and 1,049 cases of clinically suspected meningitis (CSM). The estimated average annual incidence of ABM was high at 145 per 100,000 population in the <2-month age group, 56 per 100,000 in the 2–23-month age group, but lower at 5 per 100,000 in the 5–14-year age group. The most common causes of ABM were Streptococcus pneumoniae (n = 44), Neisseria meningitidis (n = 42), and Gram-negative coliform bacteria (n = 26). Eighteen of 22 cases caused by pneumococcal serotypes included in PCV13 occurred prior to vaccine introduction and four afterwards. The overall case fatality ratio for ABM was 29% (49/169) and was highest in the <2-month age group 37% (10/27). The case fatality ratio was 8.6% (18/209) for suspected non-bacterial meningitis and 12.8% (134/1049) for clinically suspected meningitis cases.

Conclusions

Gambian children continue to experience substantial morbidity and mortality associated with suspected meningitis, especially acute bacterial meningitis. Such severely ill children in sub-Saharan Africa require improved diagnostics and clinical care.

Neisseria meningitidis Serogroup C Clonal Complex 10217 Outbreak in West Kpendjal Prefecture, Togo 2019

Togo has reported seasonal meningitis outbreaks caused by non-Neisseria meningitidis serogroup A (NmA) pathogens since the introduction of meningococcal serogroup A conjugate vaccine (MACV, MenAfriVac) in 2014. From 2016 to 2017, NmW caused several outbreaks. In early 2019, a NmC outbreak was detected in the Savanes region of Togo and its investigation is described here. Under case-based surveillance, epidemiological and clinical data, and cerebrospinal fluid specimens were collected for every suspected case of meningitis. Specimens were tested for meningitis pathogens using confirmatory microbiological and molecular methods. During epidemic weeks 9 to 15, 199 cases were reported, with 179 specimens being available for testing and 174 specimens (97.2%) were tested by at least one confirmatory method. The NmC was the predominant pathogen confirmed (93.9%), belonging to sequence type (ST)-9367 of clonal complex (CC) 10217. All NmC cases were localized to the West Kpendjal district of the Savanes region with attack rates ranging from 4.1 to 18.8 per 100,000 population and case fatality rates ranging up to 2.2% during weeks 9 to 15. Of the 93 NmC confirmed cases, 63.4% were males and 88.2% were in the 5 to 29 age group. This is the first report of a NmC meningitis outbreak in Togo. The changing epidemiology of bacterial meningitis in the meningitis belt post-MACV highlights the importance of monitoring of emerging strain and country preparedness for outbreaks in the region.

IMPORTANCE The recent emergence of an invasive NmC strain in Togo is an example of the changing bacterial meningitis epidemiology in the meningitis belt post-MACV. The current epidemiology includes the regional circulation of various non-NmA serogroups, which emphasizes the need for effective molecular surveillance, laboratory diagnosis, and a multivalent vaccine that is effective against all serogroups in circulation.

Epidemiological Characteristics of Meningococcal Meningitis (2016 to 2018) Four Years after the Introduction of Serogroup A Meningococcal Conjugate Vaccine in Benin

Objectives. This study aims to study the epidemiological and geographic characteristics of the meningococcal serogroups four years after the introduction of serogroup A meningococcal conjugate vaccine. Methods. This is a prospective, descriptive, analytical study, and it took place from 2016 to 2018. Cerebrospinal fluid (CSF) samples were taken after the identification of meningitis cases. The samples, thus, taken were sent to the laboratory for culture and identification of Neisseria meningitidis in accordance with WHO standards. Results. Eight hundred and ninety-nine bacterial strains were identified, of which 219 were strains of Neisseria meningitidis. The majority of N. meningitidis-positive samples were from male patients (59.8%) with a median age of 4 (IQR: 1–13). Four of N. meningitidis serogroups were identified, namely, serogroups C (6.8%), W (19.6%), X (1.8%), and A (0.5%). Geographically, 92.7% of the identified N. meningitidis serogroups came from patients who lived in the northern region of the country. The departments most concerned were Alibori (N. meningitidis C (66.7%) and N. meningitidis W (20.9%)); Atacora (N. meningitidis W (41.9%), N. meningitidis X (75.0%), and N. meningitidis C (13.3%)); and Borgou (N. meningitidis W (23.3%)). Conclusion. The results of this study showed that there is an emergence of cases of meningococcal of serogroup C four years after the introduction of MenAfricVac in Benin. These results demonstrated the effectiveness of case-by-case surveillance in detecting small changes in the distribution of serogroups that could have important implications for public health strategies in the coming seasons.

Characterization of pneumococcal meningitis before and after introduction of 13-valent pneumococcal conjugate vaccine in Niger, 2010-2018

Pneumococcal meningitis in the African meningitis belt is primarily caused by Streptococcus pneumoniae serotype 1, a serotype contained in the 13-valent pneumococcal conjugate vaccine (PCV13). In 2014, Niger introduced PCV13 with doses given at 6, 10, and 14 weeks of age. We leveraged existing meningitis surveillance data to describe pneumococcal meningitis trends in Niger. As a national reference laboratory for meningitis, Centre de Recherche Médicale et Sanitaire (CERMES) receives cerebrospinal fluid specimens from suspected bacterial meningitis cases and performs confirmatory testing for an etiology by culture or polymerase chain reaction (PCR). Specimens with S. pneumoniae detection during 2010-2018 were sent to the Centers for Disease Control and Prevention for serotyping by sequential triplex real-time PCR. Specimens that were non-typeable by real-time PCR underwent serotyping by conventional multiplex PCR. We tested differences in the distribution of pneumococcal serotypes before (2010-2012) and after (2016-2018) PCV13 introduction. During January 2010 to December 2018, CERMES received 16,155 specimens; 5,651 (35%) had bacterial etiology confirmed. S. pneumoniae accounted for 13.2% (744/5,651); 53.1% (395/744) were serotyped. During 2010-12, PCV13-associated serotypes (VT) constituted three-fourths of serotyped pneumococcus-positive specimens; this proportion declined in all age groups in 2016-18, most substantially in children aged < 5 years (74.0% to 28.1%; P < 0.05). Among persons aged ≥ 5 years, VT constituted > 50% of pneumococcal meningitis after PCV13 introduction; serotype 1 remained the most common VT among persons aged ≥ 5 years, but not among those < 5 years. VT as a group caused a smaller proportion of reported pneumococcal meningitis cases after PCV13 introduction in Niger. Serotype 1, however, remains the major cause of pneumococcal meningitis in older children and adults. Different vaccination strategies, such as changing the infant vaccination schedule or extending vaccine coverage to older children and adults, are needed, in addition to stronger surveillance.

Future Directions for Meningitis Surveillance and Vaccine Evaluation in the Meningitis Belt of Sub-Saharan Africa

In sub-Saharan Africa, bacterial meningitis remains a significant public health problem, especially in the countries of the meningitis belt, where Neisseria meningitidis serogroup A historically caused large-scale epidemics. In 2014, MenAfriNet was established as a consortium of partners supporting strategic implementation of case-based meningitis surveillance to monitor meningitis epidemiology and impact of meningococcal serogroup A conjugate vaccine (MACV). MenAfriNet improved data quality through use of standardized tools, procedures, and laboratory diagnostics. MenAfriNet surveillance and study data provided evidence of ongoing MACV impact, characterized the burden of non-serogroup A meningococcal disease (including the emergence of a new epidemic clone of serogroup C), and documented the impact of pneumococcal conjugate vaccine. New vaccines and schedules have been proposed for future implementation to address the remaining burden of meningitis. To support the goals of "Defeating Meningitis by 2030," MenAfriNet will continue to strengthen surveillance and support research and modeling to monitor the impact of these programs on meningitis burden in sub-Saharan Africa.