Volume 8, Number 12—December 2002
Research
Meteorologic Influences on Plasmodium falciparum Malaria in the Highland Tea Estates of Kericho, Western Kenya
Table
Trend of malaria, climate, and malaria suitability variables, Kericho tea estates, 1966–1995a,b
| Variable | p | ADFc | β | t | p valuec | τα | Q | Sig. Q |
|---|---|---|---|---|---|---|---|---|
| Malaria incidence | 5 | -4.00 | 0.0238 | 2.49 | 0.0133 | 0.1801 | 58.7394 | 0.0097 |
| Total admissions | 6 | -2.76 | -0.0069 | -0.28 | 0.7820 | -0.4151 | 30.9302 | 0.7083 |
| Tmean met. stat. (oC) | 8 | -3.41 | 0.0004 | 1.76 | 0.0799 | -0.0211 | 40.8630 | 0.2653 |
| Rain met. stat. (mm) | 1 | -11.91 | -0.0202 | -0.52 | 0.6066 | -0.0074 | 43.3753 | 0.1858 |
| Tmean clim. (oC) | 1 | -7.51 | 0.0035 | 1.60 | 0.1103 | -0.0980 | 46.6888 | 0.1094 |
| Tmax clim. (oC) | 24 | -4.66 | 0.0070 | 1.68 | 0.0935 | 0.0592 | 22.6634 | 0.9592 |
| Tmin clim. (oC) | 1 | -8.36 | 0.0038 | 1.55 | 0.1233 | -0.1944 | 45.1424 | 0.1412 |
| Precipitation clim. (mm) | 1 | -11.70 | -0.0098 | -0.36 | 0.7205 | -0.0745 | 34.2984 | 0.5497 |
| Vapor pressure clim. (hPa) | 1 | -8.37 | 0.0038 | 1.66 | 0.0974 | -0.1829 | 45.5674 | 0.1318 |
| Garnham suitability (mo)d | 4 | -4.21 | -0.0380 | -0.89 | 0.3850 | -0.4488 | 5.6658 | 0.7729 |
aTmean, the mean monthly temperature; Tmax, the mean of maximum monthly temperatures; Tmin, the mean of minimum monthly temperatures; met. stat., meteorologic station data from the Kericho tea estate; clim., data derived from the global gridded climatology dataset (33,34).
bFigures in bold denote significance at the 5% level. p is the number of lagged differenced dependent variables selected.
cADF, the Augmented Dicke-Fuller t-test for γ=0. The 5% critical value is -3.45. Exact p values are not available for ADF and τα statistics. The distribution of the t statistic for the slope parameter β has the standard t distribution under the assumption that γ<0. τα is the t statistic for the intercept term in the autoregression without a linear time trend. This test is the appropriate one for a trend if γ=0. Its 5% critical value is 2.54. The Q statistic is a portmanteau test for general serial correlation and is distributed as chi square (39).
dGarnham suitability (1,4) refers to the number of months with a mean monthly temperature exceeding 15°C and monthly rainfall totals exceeding 152 mm (when the gridded climatology data are used). These data are therefore annual data, whereas all other time-series are monthly observations.
