Abstract

Neisseria meningitidis , the meningococcus, is part of the normal flora of the human nasopharynx yet is an important cause of morbidity and mortality worldwide. The key to reducing incidence is prevention through vaccination, because early signs of meningococcal meningitis and septicaemia can be non-distinct, the infection can progress rapidly, and can be fatal in 5-10% of cases even if treatment is initiated early. Globally six capsular groups – A, B, C, W135 , Y and increasingly X – cause most disease. In the UK, the annual incidence of meningococcal meningitis and septicaemia is currently around 2 per 100,000, largely due to serogroup B, following the successful introduction of serogroup C conjugate vaccines in 1999. New vaccines with the capacity to prevent group B disease are in late stages of development and decisions about whether and how to introduce them will need to be made soon. In Africa the ‘meningitis belt’ stretches from Senegal to Ethiopia. Here, epidemics of meningococcal meningitis occur periodically though unpredictably in the dry season, with local weekly attack rates up to 1000 per 100,000. A new serogroup A conjugate vaccine being rolled out across the region offers new hope for prevention. In this talk I will contrast the epidemiology of meningococcal carriage and disease in the UK and Africa and discuss the design and evaluation of vaccine strategies. I will draw on some of my own research, which includes mathematical modelling, seroprevalence and carriage studies.