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Volume 8, Number 12—December 2002

Research

Meteorologic Influences on Plasmodium falciparum Malaria in the Highland Tea Estates of Kericho, Western Kenya

G. Dennis Shanks*Comments to Author , Simon I. Hay†‡Comments to Author , David I. Stern§, Kimutai Biomndo¶1, and Robert W. Snow†‡
Author affiliations: *U.S. Army Medical Research Unit–Kenya, Nairobi, Kenya; †University of Oxford, Oxford, U.K.; ‡Kenya Medical Research Institute/Wellcome Trust Collaborative Programme, Nairobi, Kenya; §Rensselaer Polytechnic Institute, Troy, New York, USA; ¶Brooke Bond Central Hospital, Kericho, Kenya

Main Article

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.

Main Article

1 Dr. Biomndo is deceased.

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