Surveillance in Africa's meningitis belt: time for new targets?
Authors: Stephen K Obaro
Journal: The Lancet Global Health (2016)

Current WHO guidelines for the detection of meningococcal disease outbreaks in the meningitis belt in Africa define suspected meningitis as sudden onset of fever (>38·5°C rectal or 38·0°C axillary) and one of the following signs: neck stiffness, flaccid neck (infants), bulging fontanelle (infants), convulsion, or other meningeal signs.1WHOStandard operating procedures for enhanced meningitis surveillance in Africa. August, 2009. WHO Regional Office for Africa, Ouagadougou, Burkina Faso2009http://www.meningvax.org/files/WHO_SOP_EN_2009.pdfGoogle Scholar Although these signs are classic for meningitis, they were used when the predominant causal pathogen of these outbreaks was Neisseria meningitidis serogroup A (NmA). After widespread implementation of vaccination with MenAfriVac (NmA conjugate vaccine), the number of outbreaks caused by this strain has decreased with a relative or absolute increase in disease caused by other Neisseria strains and other bacterial species. The change in epidemiology is likely to affect clinical presentation, and review of clinical management guidelines for the subregion is urgently needed. Because confirmation of the cause of most cases during these outbreaks is difficult due to resource constraints, lessons can be learnt from disease caused by similar strains in locations where resources for evaluation and monitoring are better. In a report from the UK,2Campbell H Parikh SR Borrow R Kaczmarski E Ramsay ME Ladhani SN Presentation with gastrointestinal symptoms and high case fatality associated with group W meningococcal disease (Men W) in teenagers, England, July 2015 to January 2016.Euro Surveill. 2016; 21: 30175Crossref Scopus (71) Google Scholar an outbreak of W135 N meningitidis was observed between July, 2015, and January, 2016, in 15 adolescents who did not have any direct epidemiological, temporal, or spatial links. All these patients presented predominantly with gastrointestinal symptoms. A clinical diagnosis of meningitis was confirmed from cerebrospinal fluid in only one of the 15 patients. Septicaemia was reported in ten of 15 patients, two patients had septic arthritis, two had pneumonia, and one presented with sore throat, fatigue, and lethargy. The outcome of illness was fatal in six of the 15 patients. All culture isolates were subsequently confirmed as W.2A (a surrogate marker for the hypervirulent sequence type 11 clonal complex), apart from one patient who had pneumonia (serotyped as NT/NT/NT). Laboratory-confirmed group W invasive meningococcal disease has increased in the UK from 19 cases in 2008–09 to 176 cases in 2014–15.3Ladhani SN Ramsay M Borrow R Riordan A Watson JM Pollard AJ Enter B and W: two new meningococcal vaccine programmes launched.Arch Dis Child. 2016; 101: 91-95Crossref PubMed Scopus (79) Google Scholar The unusual presentation of invasive meningococcal disease caused by group W has also been reported in Chile, with eight fatalities in 14 cases.4Lucidarme J Hill DM Bratcher HB et al.Genomic resolution of an aggressive, widespread, diverse and expanding meningococcal serogroup B, C and W lineage.J Infect. 2015; 71: 544-552Summary Full Text Full Text PDF PubMed Scopus (157) Google Scholar Comparative data on the clinical presentation and outcome in NmC and NmA are scarce. In a brief report5Evans-Jones LG Whittle HC Onyewotu II Egler LJ Greenwood BM Comparative study of group A and group C meningococcal infection.Arch Dis Child. 1977; 52: 320-323Crossref PubMed Scopus (25) Google Scholar from northern Nigeria in 1977, 114 patients with meningococcal infection were studied, of whom 72 patients had NmC infection and 42 patients had NmA infection. All patients who had bacteraemia had disease caused by NmC infection, and nine of these 14 patients died. Clinical and laboratory findings were similar in patients with meningitis due to NmA and NmC, but arthritis and cutaneous vasculitis were more common in patients with NmC. The overall mortality rate was 22% in patients infected with NmC, and 12% in patients infected with NmA. Notably, the investigators reported similar mortality rates for both diseases when the patients who had bacteraemia were excluded from the analysis. The excess mortality rate in patients infected with NmC would have been missed in the absence of surveillance for bacteraemia. Reports of non-serogroup-A meningococcal disease in the meningitis belt are increasing, consisting of outbreaks caused by NmW, NmC, and serogroup 1 strain of Streptococcus pneumoniae in northern Ghana.6Mueller JE Yaro S Ouedraogo MS et al.Pneumococci in the African meningitis belt: meningitis incidence and carriage prevalence in children and adults.PLoS One. 2012; 7: e52464Crossref PubMed Scopus (45) Google Scholar This trend clearly shows the need to provide more comprehensive surveillance platforms for invasive meningococcal disease in the meningitis belt, where diagnosis of disease has relied on the recognition of meningeal symptoms and assessment of cerebrospinal fluid alone without consideration for patients with invasive meningococcal disease, who are at high risk of a fatal outcome. Blood cultures are not routinely done and no intensive care units exist. This change in epidemiology of disease warrants an urgent review of the surveillance and management approaches in place for these outbreaks. First, the clinical case definition should be broadened to include patients with septicaemia at clinical presentation without meningeal signs. Second, provision for integrating bacteraemia surveillance should be included in the laboratory investigation, either by blood culture or another suitable method for the detection and identification of bacteria from the blood stream. Third, the recommended threshold for outbreak alerts and epidemics should be revised because outbreaks caused by non-A meningococcal meningitis serogroups have less clear patterns of outbreak, and analysis of the epidemic risk at the subdistrict level could be poorly sensitive. Finally, improved understanding of the dynamics of these outbreaks will be best accomplished by establishing local and regional microbiological diagnostic, year-round surveillance to track disease incidence and provide causal data that will guide preventive strategies, in the short term and long term. I declare no competing interests.