Present and future climatic suitability for dengue fever in Africa

Figures & data

Table 1. List of bioclimatic variables used for modelling the distribution of Ae. aegypti and dengue occurrence.

Label	Variable	Units
bio1	Annual mean temperature	Degree Celsius
bio5	Maximum temperature of warmest month	Degree Celsius
bio6	Minimum temperature of coldest month	Degree Celsius
bio7	Annual temperature range (Bio05–Bio06)	Degree Celsius
bio12	Annual precipitation	Millimetre
bio13	Precipitation of wettest month	Millimetre
bio14	Precipitation of driest month	Millimetre

Figure 1. Variable importance (bio1 = annual mean temperature, bio5 = maximum temperature of warmest month, bio6 = minimum temperature of coldest month, bio7 = annual temperature range (Bio05–Bio06), bio12 = annual precipitation, bio13 = precipitation of wettest month, and bio14 = precipitation of driest month).

Table 2. Accuracy assessments (AUC and TSS) of five models used for predicting current and future habitat suitability for Ae. aegypti in Africa.

Performance indicator	GLM	SVM	MARS	BRT	RF
AUC	0.94	0.95	0.99	0.96	0.95
TSS	0.8	0.81	0.82	0.81	0.9

AUC: area under curve; TSS: true skill statistic; GLM: generalized linear model; SVM: support vector machine; MARS: multivariate adaptive regression splines; BRT: boosted regression trees; RF: random forest algorithm.

Table 3. Percentage of coverage by the 4 classes of habitat suitability under the current and future (2050 and 2070) climate scenarios (RCP4.5 and RCP8.5) for Ae. aegypti in relation to dengue fever incidence in Africa.

		Total suitability (%)
Decade	Scenarios	Not suitable	Low	Moderate	High
Current	-	59.3	14.2	11.2	15.2
2050	RCP4.5	52.2	12.3	13.7	21.8
	RCP8.5	50.8	11.5	14.4	23.3
2070	RCP4.5	51.1	12.9	14.7	21.3
	RCP8.5	48.5	12.6	15.2	23.7

Table 4. Percentage of % change of habitat suitability in 2050 and 2070 climate scenarios (RCP4.5 and RCP8.5) for Ae. aegypti compared to the current climatic condition.

Decade	Scenarios	Change (%) compared to current suitability
		Not suitable	Low	Moderate	High
		-	-	-	-
Current	-	−11.9	−13.6	21.8	43.3
2050	RCP4.5	−14.3	−19.2	28.0	53.2
	RCP8.5	−13.8	−9.4	30.7	40.1
2070	RCP4.5	−18.2	−11.5	35.1	55.8

Figure 2. Map showing the current habitat suitability for Ae. aegypti in relation to dengue fever incidences in Africa. Grey to green colours illustrate gradients of habitat suitability from low to high.

Figure 3. Future continental suitability for Ae. aegypti associated with dengue fever incidences in Africa by 2050 under RCP4.5 (A) and RCP 8.5 (B) and by 2070 under RCP4.5 (C) and RCP 8.5 (D). Grey to green colours illustrate the gradient of suitability from low to high.