Correlations between climate and meningitis in Niger and Burkina Faso. (A) Correlation coefficients between the MCM annual log-incidence rates in Niger and 7 monthly averaged atmospheric variables over Niger. The correlations are computed for each month from October to January over the 1968–2005 period. The monthly atmospheric variables from October to December of the year y are correlated with the MCM log-incidence rate of the following year y+1, while the monthly atmospheric variables in January of the year y are correlated with the incidence MCM rate of the same year y. Significant values at the 99% confidence interval are outside of the shaded box (see Materials and Methods for details on the significance test). The atmospheric variables (Tab.3) are: UWND the zonal wind, VWND the meridional wind, SLP the seal-level pressure, MOD the wind speed, AIR the surface temperature, RHUM the relative humidity and SHUM the specific humidity. (B) Same as (A) but for atmospheric variables and MCM incidence in Burkina Faso.