title: Timely detection of bacterial meningitis epidemics at district level: a study in three countries of the African Meningitis Belt.
abstract: BACKGROUND
  Bacterial meningitis is a major public health problem in the African 'Meningitis Belt', where recurrent unpredictable epidemics occur. Despite the introduction in 2010 of the conjugate A vaccine, the reactive strategy remains important for responding to epidemics caused by other bacteria and in areas not yet vaccinated. Review of weekly numbers of suspected cases in Niger, Mali and Burkina Faso identified spatial disparities in the annual patterns of meningitis, which suggested a more local way of defining epidemics and initiating a timely vaccination campaign.
  
  
  METHODS
  We defined an epidemic district-year as an excess of cases compared to the incidence previously experienced in the given district. Groups of similar districts in terms of seasonal patterns were identified by cluster analysis. We investigated a cluster-specific criterion of early epidemic onset to anticipate epidemic district-years.
  
  
  RESULTS
  These were encouraging, as epidemic district-years were fairly efficiently captured, with an average time gained of 2.5 weeks over the current strategy.
  
  
  CONCLUSIONS
  This early-onset criterion could help ensure timely implementation of vaccination campaigns without the need to modify the implemented surveillance system. The next step is to extend this study to other countries of the Meningitis Belt, and to explain the differences in seasonal patterns in the different clusters.
authors.affiliation: Epidemic and Pandemic Alert and Response, World Health Organization, Geneva, Switzerland. l.agier@lancaster.ac.uk
authors.forename: Lydiane
authors.initials: L
authors.lastname: Agier
authors.forename: Hélène
authors.initials: H
authors.lastname: Broutin
authors.forename: Eric
authors.initials: E
authors.lastname: Bertherat
authors.forename: Mamoudou H
authors.initials: MH
authors.lastname: Djingarey
authors.forename: Clement
authors.initials: C
authors.lastname: Lingani
authors.forename: William
authors.initials: W
authors.lastname: Perea
authors.forename: Stéphane
authors.initials: S
authors.lastname: Hugonnet
mesh_terms: D002050:Burkina Faso / Q000453:epidemiology; D016000:Cluster Analysis; D006801:Humans; D015994:Incidence; D008302:Mali / Q000453:epidemiology; D016920:Meningitis, Bacterial / Q000453:epidemiology*; D009548:Niger / Q000453:epidemiology