23 Caugant DA. Population genetics and molecular epidemiology of Neisseria meningitidis. APMIS 1998; 106: 505–25. 24 Spiegel A, Greindl I, Bordonado JL, et al. Fiabilite du diagnostic de meningite cerebospinale en periode epidemique. A propos de l’epidemie de Tchad en 1988. Bull Soc Pathol Exot 1990; 83: 642–48. 25 Lewis R, Nathan N, Communier A, et al. Mieux detecter les epidemies de meningite a meningocoque en Afrique: une nouvelle recommendation. Cahiers Sante (in press). 26 Wenger J, Tikhomirov E, Barakamfitiye D, Bele O, Heymann DL. Meningococcal vaccine in sub-Saharan Africa. Lancet 1997; 350: 1709. 27 Kaninda AV, Varaine F, Henkens M, Paquet C. Meningococcal vaccine in sub-Saharan Africa. Lancet 1997; 350: 1708. 28 Reingold AL, Hightower AW, Bolan GA, et al. Age-specific differences in duration of clinical protection after vaccination with meningococcal polysaccharide A vaccine. Lancet 1985; 2: 114–18. 29 MacLennan J, Obaro S, Deeks J, et al. Immune response to revaccination with meningococcal A and C polysaccharides in Gambian children following repeated immunisation during early childhood. Vaccine 1999; 17: 3086–93. 30 Hassan-King MKA, Wall RA, Greenwood BM. Meningococcal carriage, meningococcal disease and vaccination. J Infect 1988; 16: 55–59. 31 Blakebrough IS, Greenwood BM, Whittle HC, Bradley AK. Failure of meningococcal vaccination to stop the transmission of meningococci in Nigerian schoolboys. Ann Trop Med Parasitol 1983; 77: 175–78. 32 Campagne G, Garba A, Fabre P, et al. Safety and immunogenicity of three doses of a Neisseria meningitidis A+C diphtheria conjugate vaccine in infants from Niger. Pediatr Infect Dis J 2000; 19: 144–50. ARTICLES