Figure 2

K-Ripley analysis (Null-model) of the meningitis epidemic events for the Western and Northern subregions, in 13 health districts, Burkina Faso, 2004–2014. (a,c)Western subregion: Hauts-Bassin region and Dédougou district. (b,d)Northern subregion: Nord region. Boulsa district was excluded from this analysis due to the low number of epidemic events detected. Black lines, number of pairs of epidemic HC that are closer than a given spatio-temporal horizon on the x-axis: 1, 2 and 3 weeks for spatial horizons ranging from 0 to 100/150 km. Red lines, 5th and 95th percentile of resampled distributions over 20 simulations of the generative model. (a, b) Null model without clustering or correlation. (c,d) Model incorporating both spatial clustering and temporal correlation blue line: range over which the observed K-Ripley is higher than the null models (Western 0–150 km, Northern: 0–70 km).