Table 1 Results of uni-variate analysis from Stage 1. Odds Ratios (AIC in parentheses) from univariate logistic regression analysis of 50 different environmental variables from 7 themes, against malaria prevalence. P-values were non-significant (n.s.), <0.05(*), <0.01(**) or <0.0005 (***), n = 122. The equation was logit(prevalence) = coefficient × co-variate + constant. NDVI = normalized difference vegetation index.

Annual mean (total for rainfall)

1.0085 (27.6)**

4.22 (13.6)***

1.094 (12.8)***

1.091 (28.9)*

1.07 (31.3) n.s.

Annual maximum (highest monthly value)

1.045 (20.8)***

3.034 (23.3)***

1.067 (11.7)***

1.090 (25.7)***

10.4 (32.2) n.s.

Annual minimum (lowest monthly value)

3.29 (13.9)***

1.11 (17.1)***

1.1048 (29.8)*

1.06 (32.7) n.s.

Annual range (highest minus lowest month)

0.52 (27.1)**

1.12 (15.8)***

1.14 (30.8)*

1.03 (32.7) n.s.

Standard deviation (Appendix)

1.03 (21.9)***

0.54 (25.0)***

0.54 (14.7)**

1.073 (26.6)***

1.03 (32.8) n.s.

Proportional standard deviation (Appendix)‡

61.8 (13.0)***

-214 (17.3)***

0.004 (33.4) n.s.

0.1 (26.8)***

43.3 (32.9) n.s.

Summer mean (total for rainfall) Dec–Mar

1.012 (22.9)***

2.59 (27.1)***

1.065 (11.6)***

1.078 (28.9)*

Winter mean (total for rainfall) Apr–Oct

0.88 (14.8)***

3.22 (12.0)***

1.11 (16.0)***

1.097 (28.6)**

Concentration (see Appendix)

1.39 (13.3)***

Number of months >80 mm (>60 & >40 mm n.s.)

1.81 (26.6)**

Number of months >16°C

2.72 (18.9)***

Number of months >165 (other cut-offs were n.s.)

1.13 (31.5) n.s.

Total in months with more than 80 mm

1.0059 (24.0)***

Total degree months above 16°C

1.050 (15.7)***

Effective temperature (Appendix)

21.8 (12.6)***

Mean daily minimum of coldest month

2.29 (21.4)***

Elevation

0.997 (29.7)**

Log distance to perennial water (m)

0.56 (21.6)***

Log distance to perennial/non-perennial water (m)

0.72 (30.5)**

Land cover (binary; moist versus dry areas)

4.76 (25.5)***

Month of survey (binary; peak season April/May versus rest of year)

8.67 (29.4)***