From genomics to surveillance, prevention and control: New challenges for the African meningitis belt

Jean Michel Alonso, Eric Bertherat, William Perea, Ray Borrow, Suzanne Chanteau, Catherine Cohet, Betty Dodet, Brian Greenwood, F. Marc LaForce, Erwan Muros Le Rouzic, Rémy Teyssou, Rasmata Ouedraogo-Traoré, Idrissa Sow

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Meningococcal meningitis occurs occasionally in small outbreaks globally, but the highest burden of the disease is in sub-Saharan Africa, in the so-called meningitis belt. This region stretches from Senegal to Ethiopia (Fig. 1), and includes an estimated risk population of 250 million [1-4]. The area is characterized by high levels of seasonal endemicity with large epidemics occurring cyclically. During epidemics, attack rates can be as high as 1000 cases per 100,000 population, causing high levels of excessive morbidity and mortality among children and young adults [1,5]. The case-fatality rate is 10% or more, although this varies between and during the course of epidemics. A further 10-20% of patients develop severe neurological sequelae [5,6]. In the meningitis belt, outbreaks occurring during the past 10 years (1995-2004) have resulted in close to 700,000 cases and 60,000 deaths. The largest recorded outbreak, in 1996, caused 250,000 cases and almost 25,000 deaths. Between epidemics, meningococcal disease is endemic in the African meningitis belt, primarily affecting children under 5 years of age. The World Heath Organization (WHO) currently recommends a reactive vaccination strategy because the immune response induced by available and affordable polysaccharide vaccines is relatively short-lived (3-5 years). These vaccines are also thought to be poorly immunogenic in children under 2 years of age, and to have little or no impact on carriage and transmission of meningococci [2]. This reactive vaccination strategy is based on rapid detection of epidemics, intervention with antibiotics to treat cases and mass vaccination with a meningococcal polysaccharide vaccine to halt the outbreak [2]. Epidemiological patterns of the disease in Africa have been changing with the occurrence of outbreaks outside the meningitis belt and with the emergence of serogroup W135. Until 2000, the vast majority of African outbreaks was caused by Neisseria meningitidis serogroup A and could be controlled with a widely available A/C meningococcal polysaccharide vaccine. The emerging W135 strain first caused an epidemic among Hajj pilgrims in 2000 and then emerged in the meningitis belt, leading to a large-scale meningitis outbreak in Burkina Faso in 2002 [2,5]. This changing epidemiology highlights the requirement for enhanced laboratory surveillance and confirmation of the strain responsible for the outbreak to adapt the vaccination strategy using the bivalent (A/C) polysaccharide vaccine, or the trivalent (A/C/W135) vaccine developed in response to the 2002 outbreak in Burkina Faso, the availability of which is limited. It also puts into question the mid- and long-term strategies aimed at eliminating epidemic meningococcal disease in Africa with the monovalent A conjugate vaccine currently in development. To address these new challenges, an international conference11"Challenges in the African Meningitis Belt: From Genomics to Surveillance, Control and Prevention Strategies", organized by the Institut Pasteur and Cermes, in partnership with the Fondation Merieux, Niamey, Niger, 26-29 November 2005. held in Niamey, Niger, brought together more than 100 delegates. Representatives from Africa, Europe and America were present, from the public and private sectors, academia, governmental, WHO and other international agencies and NGOs, specializing in various disciplines: health care personnel from the field, clinicians, laboratory workers, researchers (epidemiologists, microbiologists, immunologists) and public health specialists. The conference offered a unique opportunity to assess the current situation, including a review of the most recent epidemiology and bacteriology data. It provided an opportunity for experts to improve their understanding of the dynamics of the disease and to discuss alternative strategies for timely and effective detection of outbreaks and for controlling them. It was also the occasion to evaluate new tools and their use in the field and to explore strategies for the development and introduction of new affordable prophylactic vaccines for Africa.

Original languageEnglish
Pages (from-to)4279-4284
Number of pages6
JournalVaccine
Volume24
Issue number20
DOIs
Publication statusPublished - 15 May 2006
Externally publishedYes

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