Surveillance in Africa's meningitis belt: time for new targets?

Encephalitis and meningitis in Western Africa: a scoping review of pathogens

OBJECTIVE

To give an overview of the recently reported literature on the aetiologies of meningitis and encephalitis in western sub-Saharan Africa.

METHODS

We conducted a scoping review following PRISMA guidance on published meningitis and encephalitis cases in the 16 countries of the United Nations-defined western sub-Saharan African region as identified in cohort studies, case series, and case reports, published 01/01/2000-08/01/2020, and available in four databases in August 2020 with an abstract in English, French or Italian.

RESULTS

There were 38 distinct pathogens identified from 91 cohort studies' data and 48 case reports or case series' data. In cohort-level data, the majority of cases were caused by Neisseria meningitidis (71.5%), Streptococcus pneumoniae (17.6%) and Haemophilus influenzae (7.3%). In case report- and case series-level data, 40.5% of patients were <18 years old, 28.6% were female, and 28.6% were known to be immunocompromised. The case fatality rate was 39.3%. The most commonly reported pathogens among immunocompetent patients were Salmonella species (13 cases) and Ebola virus (9 cases), and the most commonly reported pathogen among immunocompromised patients was Cryptococcus neoformans (18 cases). Most cohort cases (52.3%) derived from Niger followed by Burkina Faso (28.6%). Most cases from single reports or series were reported from Nigeria (21.4%), Mali (20.2%) and Burkina Faso (19.0%).

CONCLUSIONS

Given the small number of pathogens reported, our findings underscore the need to better screen, diagnose and monitor populations in western sub-Saharan Africa for additional CNS pathogens, including those posing significant outbreak risks.

Meningococcus serogroup C clonal complex ST-10217 outbreak in Zamfara State, Northern Nigeria

After the successful roll out of MenAfriVac, Nigeria has experienced sequential meningitis outbreaks attributed to meningococcus serogroup C (NmC). Zamfara State in North-western Nigeria recently was at the epicentre of the largest NmC outbreak in the 21^st Century with 7,140 suspected meningitis cases and 553 deaths reported between December 2016 and May 2017. The overall attack rate was 155 per 100,000 population and children 5–14 years accounted for 47% (3,369/7,140) of suspected cases. The case fatality rate (CFR) among children 5–9 years was 10%, double that reported among adults ≥ 30 years (5%). NmC and pneumococcus accounted for 94% (172/184) and 5% (9/184) of the laboratory-confirmed cases, respectively. The sequenced NmC belonged to the ST-10217 clonal complex (CC). All serotyped pneumococci were PCV10 serotypes. The emergence of NmC ST-10217 CC outbreaks threatens the public health gains made by MenAfriVac, which calls for an urgent strategic action against meningitis outbreaks.