The dynamics of meningococcal carriage in Africa and the impact of vaccination.

The goals of this project are (a) identification of carriers of serogroup A meningococci in countries of the African meningitis belt (b) characterisation of the dynamics of carriage within households and how this is influenced by vaccination (c) investigation of the relationship between carriage of potentially pathogenic meningococci and of non-pathogenic Neisseria before and after vaccination. Cross-sectional carriage surveys will be carried out in seven countries including subjects of all ages and urban and rural populations. Carriers of serogroup A meningococci identified during these surveys will be studied in detail. A nested case control study will identify risk factors for carriage. Household contacts of carriers will be swabbed at monthly intervals for a period of 6 months to identify the pattern of transmission within households, acquisition rate and duration of carriage. Measurement of baseline bactericidal antibody concentrations will allow correlates of protection ag ainst carriage to be determined. These studies will be repeated in three countries after vaccination. In countries where vaccination is not introduced, longitudinal surveys will be conducted. To determine the relationship between carriage of potentially pathogenic meningococci and non-pathogenic Neisseria, neisserial isolates obtained before and after introduction of vaccination will be characteristed by multilocus sequence typing (MLST).