Fig 1. Annual meningitis incidences at health area level in three selected districts, Niger, 2002–2012.

One district was selected for illustration in each of the three regions: A) Konni district in Tahoua region, B) Say district in Tillabery region, and C) Boboye district in Dosso region. Boxplots show median, 25^th and 75^th percentile and range of annual incidences in the health areas of the district. Dotted lines indicate annual incidence of 100 per 100,000, a threshold previously used as a retrospective definition of epidemics at the district level.¹³ The epidemiological year n, from 1^st July of calendar year n-1 to 30^th June of calendar year n, is used here.