Meningococcal Meningitis Surveillance in the African Meningitis Belt, 2004-2013.

BACKGROUND: An enhanced meningitis surveillance network was established across the meningitis belt of sub-Saharan Africa in 2003 to rapidly collect, disseminate, and use district weekly data on meningitis incidence. Following 10 years' experience with enhanced surveillance that included the introduction of a group A meningococcal conjugate vaccine, PsA-TT (MenAfriVac), in 2010, we analyzed the data on meningitis incidence and case fatality from countries reporting to the network. METHODS: After de-duplication and reconciliation, data were extracted from the surveillance bulletins and the central database held by the World Health Organization Inter-country Support Team in Burkina Faso for countries reporting consistently from 2004 through 2013 (Benin, Burkina Faso, Chad, Democratic Republic of Congo, Ghana, Côte d'Ivoire, Mali, Niger, Nigeria, Togo). RESULTS: The 10 study countries reported 341 562 suspected and confirmed cases over the 10-year study period, with a marked peak in 2009 due to a large epidemic of group A Neisseria meningitidis (NmA) meningitis. Case fatality was lowest (5.9%) during this year. A mean of 71 and 67 districts annually crossed the alert and epidemic thresholds, respectively. The incidence rate of NmA meningitis fell >10-fold, from 0.27 per 100,000 in 2004-2010 to 0.02 per 100,000 in 2011-2013 (P < .0001). CONCLUSIONS: In addition to supporting timely outbreak response, the enhanced meningitis surveillance system provides a global overview of the epidemiology of meningitis in the region, despite limitations in data quality and completeness. This study confirms a dramatic fall in NmA incidence after the introduction of PsA-TT

Response thresholds for epidemic meningitis in sub-Saharan Africa following the introduction of MenAfriVac®.

BACKGROUND: Since 2010, countries in the African meningitis belt have been introducing a new serogroup A meningococcal conjugate vaccine (MenAfriVac(®)) through mass campaigns. With the subsequent decline in meningitis due to Neisseria meningitidis serogroup A (NmA) and relative increase in meningitis due to other serogroups, mainly N. meningitidis serogroup W (NmW), the World Health Organisation (WHO) initiated a review of the incidence thresholds that guide response to meningitis epidemics in the African meningitis belt. METHODS: Meningitis surveillance data from African meningitis belt countries from 2002 to 2013 were used to construct a single NmW dataset. The performance of different weekly attack rates, used as thresholds to initiate vaccination response, on preventing further cases was estimated. The cumulative seasonal attack rate used to define an epidemic was also varied. RESULTS: Considerable variation in effect at different thresholds was observed. In predicting epidemics defined as a seasonal cumulative incidence of 100/10(5) population, an epidemic threshold of 10 cases/10(5) population/week performed well. Based on this same epidemic threshold, with a 6 week interval between crossing the epidemic threshold and population protection from a meningococcal vaccination campaign, an estimated 17 cases per event would be prevented by vaccination. Lowering the threshold increased the number of cases per event potentially prevented, as did shortening the response interval. If the interval was shortened to 4 weeks at the threshold of 10/10(5), the number of cases prevented would increase to 54 per event. CONCLUSIONS: Accelerating time to vaccination could prevent more cases per event than lowering the threshold. Once the meningitis epidemic threshold is crossed, it is of critical importance that vaccination campaigns, where appropriate, are initiated rapidly

Serogroup W Meningitis Outbreak at the Subdistrict Level, Burkina Faso, 2012

In 2012, Neisseria meningitidis serogroup W caused a widespread meningitis epidemic in Burkina Faso. We describe the dynamic of the epidemic at the subdistrict level. Disease detection at this scale allows for a timelier response, which is critical in the new epidemiologic landscape created in Africa by the N. meningitidis A conjugate vaccine

Bacterial meningitis epidemiology and return of <i>Neisseria meningitidis</i> serogroup A cases in Burkina Faso in the five years following MenAfriVac mass vaccination campaign

<div><p>Background</p><p>Historically, <i>Neisseria meningitidis</i> serogroup A (NmA) caused large meningitis epidemics in sub-Saharan Africa. In 2010, Burkina Faso became the first country to implement a national meningococcal serogroup A conjugate vaccine (MACV) campaign. We analyzed nationwide meningitis surveillance data from Burkina Faso for the 5 years following MACV introduction.</p><p>Methods</p><p>We examined Burkina Faso’s aggregate reporting and national laboratory-confirmed case-based meningitis surveillance data from 2011–2015. We calculated incidence (cases per 100,000 persons), and described reported NmA cases.</p><p>Results</p><p>In 2011–2015, Burkina Faso reported 20,389 cases of suspected meningitis. A quarter (4,503) of suspected meningitis cases with cerebrospinal fluid specimens were laboratory-confirmed as either <i>S</i>. <i>pneumoniae</i> (57%), <i>N</i>. <i>meningitidis</i> (40%), or <i>H</i>. <i>influenzae</i> (2%). Average adjusted annual national incidence of meningococcal meningitis was 3.8 (range: 2.0–10.2 annually) and was highest among infants aged <1 year (8.4). <i>N</i>. <i>meningitidis</i> serogroup W caused the majority (64%) of meningococcal meningitis among all age groups. Only six confirmed NmA cases were reported in 2011–2015. Five cases were in children who were too young (n = 2) or otherwise not vaccinated (n = 3) during the 2010 MACV mass vaccination campaign; one case had documented MACV receipt, representing the first documented MACV failure.</p><p>Conclusions</p><p>Meningococcal meningitis incidence in Burkina Faso remains relatively low following MACV introduction. However, a substantial burden remains and NmA transmission has persisted. MACV integration into routine childhood immunization programs is essential to ensure continued protection.</p></div

Aggregate and case-based meningitis surveillance data indicators, Burkina Faso, 2011–2015.

<p>Aggregate and case-based meningitis surveillance data indicators, Burkina Faso, 2011–2015.</p

Average adjusted annual incidence of laboratory-confirmed meningitis by pathogen and age group, Burkina Faso, 2011–2015.

<p>Abbreviations: Hi, <i>H</i>. <i>influenzae</i>; NmA, <i>N</i>. <i>meningitidis</i> serogroup A; NmC, <i>N</i>. <i>meningitidis</i> serogroup C; NmW, <i>N</i>. <i>meningitidis</i> serogroup W; NmX, <i>N</i>. <i>meningitidis</i> serogroup X; NmY, <i>N</i>. <i>meningitidis</i> serogroup Y; Sp, <i>S</i>. <i>pneumoniae</i>.</p

Adjusted annual incidence of meningococcal meningitis by serogroup, Burkina Faso, 2011–2015.

<p>Abbreviations: Nm, <i>N</i>. <i>meningitidis</i>; NmA, <i>N</i>. <i>meningitidis</i> serogroup A; NmC, <i>N</i>. <i>meningitidis</i> serogroup C; NmW, <i>N</i>. <i>meningitidis</i> serogroup W; NmX, <i>N</i>. <i>meningitidis</i> serogroup X; NmY, <i>N</i>. <i>meningitidis</i> serogroup Y.</p