title: Meningitis outbreaks and vaccination strategy.
abstract: Three outbreaks of meningitis caused by Neisseria meningitidis serogroup A (subgroup III) are described: Niger (1991), Burundi (1992), and Guinea (1993). These outbreaks showed unusual characteristics: a shorter inter-epidemic interval (Niger), unusual geographical location outside the meningitis belt (Burundi and Guinea), and high age-specific attack rates in all age groups (Burundi and Guinea). Mass immunization campaigns mobilized considerable human and financial means (US $322,000 and 3000 person-days of work for health personnel to immunize 629,000 people in Guinea). The vaccination coverage was over 80% in densely populated areas (Burundi and urban Guinea), but below 50% in less populated areas (24/27 and 26/30 sub-districts in Niger and Guinea, respectively). The preventive fraction (proportion of cases prevented by vaccination) was substantial in Guinea (35% for a vaccine efficacy of 85%) and was higher where the campaign was initiated earlier. An 'alert' threshold indicating the onset of an epidemic of 15/100,000 cases in one week showed good sensitivity (94%), specificity (98%) and positive predictive value (89%) in Burundi, permitting quick decision making outside the meningitis belt. These 3 meningococcal meningitis outbreaks show the need for epidemic emergency preparedness and for vigilance on the whole African continent.
authors.affiliation: WHO Collaborating Centre for Reference and Research on Meningococci, National Institute of Public Health, Oslo, Norway.
authors.forename: F
authors.initials: F
authors.lastname: Varaine
authors.forename: D A
authors.initials: DA
authors.lastname: Caugant
authors.forename: J Y
authors.initials: JY
authors.lastname: Riou
authors.forename: M K
authors.initials: MK
authors.lastname: Kondé
authors.forename: G
authors.initials: G
authors.lastname: Soga
authors.forename: D
authors.initials: D
authors.lastname: Nshimirimana
authors.forename: G
authors.initials: G
authors.lastname: Muhirwa
authors.forename: D
authors.initials: D
authors.lastname: Ott
authors.forename: E A
authors.initials: EA
authors.lastname: Høiby
authors.forename: F
authors.initials: F
authors.lastname: Fermon
authors.forename: A
authors.initials: A
authors.lastname: Moren
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002063:Burundi / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000517:prevention & control*; D005544:Forecasting / Q000379:methods; D016701:Guinea / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008585:Meningitis, Meningococcal / Q000453:epidemiology* / Q000401:mortality / Q000517:prevention & control*; D009345:Neisseria meningitidis / Q000145:classification / Q000302:isolation & purification; D009548:Niger / Q000453:epidemiology; D012680:Sensitivity and Specificity; D014611:Vaccination / Q000191:economics