ABSTRACT
Objective To better understand the characteristics of spatial distribution of malaria epidemics in Hainan province and to explore the relationship between malaria epidemics and environmental factors, as well to develop prediction model on malaria epidemics. Methods Data on Malaria and meteorological factors were collected in all 19 counties in Hainan province from May to Oct. , 2000, and the proportion of land use types of these counties in this period were extracted from digital map of land use in Hainan province. Land surface temperatures (LST)were extracted from MODIS images and elevations of these counties were extracted from DEM of Hainan province. The coefficients of correlation of malaria incidences and these environmental factors were then calculated with SPSS 13.0, and negative binomial regression analysis were done using SAS 9.0. Results The incidence of malaria showed (1) positive correlations to elevation, proportion of forest land area and grassland area; (2) negative correlations to the proportion of cultivated area, urban and rural residents and to industrial enterprise area, LST; (3) no correlations to meteorological factors, proportion of water area, and unemployed land area. The prediction model of malaria which came from negative binomial regression analysis was: Ⅰ(monthly, unit:1/1 000 000) = exp( - 1. 672 - 0. 399 × LST). Conclusion Spatial distribution of malaria epidemics was associated with some environmental factors, and prediction model of malaria epidemic could be developed with indexes which extracted from satellite remote sensing images.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of low intensity and very high frequency (VHF) electromagnetic radiation (170 MHz) on nervous system function and serum enzymes and immune function in human subjects with occupational exposure to VHF.</p><p><b>METHODS</b>To measure the intensity of VHF and other environmental factors on the spot, to hold the questionnaire about chief complaints, to examine the rheoencephalography and the neurobehavior function, to analyze ALT, AST, ALP and LDH, and IgA, IgM and IgG in experimental group and control group.</p><p><b>RESULTS</b>The intensity of VHF (direction of antenna: 0 degrees, 10 m and 135 degrees, 20 m) was higher than that of national standard on-the-spot. The incidences of symptoms such as headache, insomnia and amnesia etc. was significantly higher in experimental group (P < 0.01). Rheoencephalography indicated that the raising time of both left [(0.155 3 +/- 0.057 9) s] and right [(0.154 1 +/- 0.059 2) s] in the experimental group after exposure were significantly longer than before exposure [(0.104 4 +/- 0.030 2) s, (0.103 2 +/- 0.030 4) s respectively] or in the control [(0.118 5 +/- 0.056 8) s, (0.117 7 +/- 0.057 5) s respectively, (P < 0.01)]. Neurobehavior function test showed that digital symbol, digital span and pursuit aiming test were decreased after exposure in the experimental group (P < 0.01). Serum enzyme analysis showed that AST, ALP and LDH were significantly increased after exposure in the experimental group (P < 0.01). No marked change was found in IgA level, while the levels of IgM and IgG after exposure in the experimental group especially the latter were significantly increased (P < 0.01).</p><p><b>CONCLUSIONS</b>Low-intensity VHF radiation can decrease the nervous system function in occupationally exposed personnel and induce increase in some kinds of enzymes and immunoglobulins.</p>