Table 2.
Potential risk or protective covariates collected from remote sensing and GIS-based sources
| Variable | Source/satellite | Details |
|---|---|---|
| Distance to health facility | GIS-derived | Euclidean distance from active health facility at time of survey (based on survey location) |
| Distance to main roads | GIS-derived [81] | Euclidean distance from major roads |
| Distance to urban centers | GIS-derived | Euclidean distance from center with population ≥ 5000 individuals |
| Distance to water bodies | GIS-derived [82] | Euclidean distance from rivers and standing water bodies |
| Elevation | CGIAR SRTM [83] | Meters above sea level |
| Land surface temperature—daya | NASA (Terra) MOD13A3 (Aqua) MYD13A3 [84] | Average monthly daytime temperature (in degrees Celsius) 30 days prior to a survey |
| Land surface temperature—night | NASA (Terra) MOD13A3 and (Aqua) MYD13A3 [84] | Average monthly nighttime temperature (in degrees Celsius) 30 days prior to a survey |
| Normalized difference vegetative indexa | NASA (Terra) MOD13A3 and (Aqua) MYD13A3 [85] | The maximum monthly index 30 days prior to a survey |
| Population density | WorldPop [86] | Population density per 100 m grid, log-transformed |
| Population density (≤ 5 y.o.)a | WorldPop [86] | Population under 5 years of age density per 100 m grid, log-transformed |
| Rainfall (historical)a | WorldClim [87] | Average of the cumulative sum of precipitation from 3 to 1 month prior to the survey date from past 50 years |
| Rainfall (current)a | FEWSNET [88] | Average of the cumulative sum of precipitation from 3 to 1 month prior to survey |
| Slope | GIS-derived (from elevation) |
aRemoved from models due to high correlations (R2 ≥ 0.49) with one or more other variables