Establishment of a cocrystal characterization method for sacubitril valsartan sodium / 药学学报

Sacubitril valsartan sodium (LCZ696) is an ionic cocrystal drug. The purpose of this study was to explore the cocrystal features of LC696 by establishing a variety of characterization methods, and thus provide basic research data for effective quality control. The cocrystal characteristics of LCZ696 and its tablets were identified by applying analytical means including powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FTIR), Raman spectra (RM), differential scanning calorimetry (DSC) and solid-state nuclear magnetic resonance spectroscopy (ssNMR). The crystalline water and hygroscopicity of LCZ696 were analyzed by thermogravimetric analysis (TGA), dynamic vapor sorption (DVS), hygroscopicity test and Karl Fischer reaction method. The results show that PXRD, FTIR, DSC and ssNMR can effectively distinguish the features of LCZ696 cocrystal, sacubitril monomer, valsartan monomer, and sacubitril-valsartan (1∶1) mixture. RM can be used as a supplementary approach. Combined with the analysis by TGA, DVS, hygroscopicity test and Karl Fischer reaction method results, LCZ696 contains 2.5 crystalline water molecules and is very hygroscopic; we recommend that LCZ696 be stored in an environment with a relative humidity below 60%. By characterizing the crystal features we can establish quality control measure and evaluate the stability of the drug tablets. This study provides data in support for the establishment of the LCZ696 quality standard.

Spatial epidemiological study on malaria epidemics in Hainan province / 中华流行病学杂志

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.

An investigation on hepatitis E virus infection status among livestock in Xi'an area / 中华流行病学杂志

<p><b>OBJECTIVE</b>To explore the carrier state of hepatitis E virus(HEV) in livestock in Xi'an area.</p><p><b>METHODS</b>Bile samples from swine, canine, sheep and cow were collected from a local slaughtering house. Reverse transcriptase nested polymerase chain reaction (RT-nPCR) was employed to amplify the ORF2 region in HEV RNA genome. All positive samples were sequenced and compared with data from GenBank. Homology analysis was conducted based on the outcome of sequencing.</p><p><b>RESULTS</b>194, 178, 79 and 191 bile samples from swine, canine, cow and sheep were collected. Positive rates with RT-nPCR method in these domestic animals were 4.10%, 0%, 0% and 0% respectively. Genetic distance analysis indicated that strains being identified were close to genotype IV of HEV, then genotype I, II and III in nucleic acid. Same outcome was shown by the same analysis on amino acid.</p><p><b>CONCLUSION</b>Swine was the only reservoir of HEV in livestock and genotype IV was the prevalent genotype.</p>

The mechanism of HBV infection of human trophoblast cell / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To observe the changes of human trophoblast cells after infected with hepatitis B virus.</p><p><b>METHODS</b>HBV positive serum was used to infect human trophoblast cells in vitro. HBsAg in cell culture medium were detected by ELISA method and HBV DNA in cell culture medium and cells were detected by PCR method. HBV fluorescence polymerase chain reaction diagnose kit were used to detect the HBV DNA concentration. Ultra structure of trophoblast cells were observed with transmission electron microscopy (TEM).</p><p><b>RESULTS</b>HBsAg could be detected in infection group by ELISA. Infection group cell culture medium and infection group cells were HBV DNA positive. HBV DNA concentrations in HBV infection cell culture medium in 0, 12, 36, 60, 84 h after extensively PBS washed were < 10(3), 3 x 10(4), 6 x 10(5), 5 x 10(5), 3 x 10(5) copies/mL. HBV infected trophoblast cells were found many forms of endosomes, some of which contents virus like particle.</p><p><b>CONCLUSION</b>HBV might take advantage of clathrin-mediated endocytosis to enter trophoblast cell, which might lead to cell infection or across the cell bar by transcytosis.</p>

A follow-up study on the efficacy of hepatitis B immunoglobulin combining hepatitis B vaccine in infants born to HBsAg positive mothers / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the efficacy of hepatitis B immunoglobulin (HBIG) combining hepatitis B vaccine in high risk infants born to HBsAg positive mothers through a follow-up study program.</p><p><b>METHODS</b>184 infants (4 twin pairs) born to HBsAg carrier mothers who were consecutively recruited from December 2002 to August 2004 were followed. Major HBV serologic markers in all infants were detected by enzyme-linked immunosorbent assay (ELISA) when they were at birth, at 7th, at 24th and at 36th months.</p><p><b>RESULTS</b>7 of the 184 infants were HBsAg positive at birth, making the transplacental intrauterine infection rate of HBV as 3.80% (7/184). 125 infants were followed up at 7th months and 108 infants were followed up at 24th and 36th months. Only 2 of the 7 infants born to HBsAg-positive and HBeAg-positive mothers were persistently sera positive for HBsAg, making the chronic infection rate of HBV as 28.57%. The other 140 infants were HBsAg negative during t he follow-up period. The rate o f detectable anti-HBs i ninfants was 7.02% at birth. After infants were immunized by HBIG combining hepatitis B vaccine, the anti-HBs-positive rate reached 92% at 7th months, and gradually descended thereafter. 72.04% of the infants at 24th and 60% at 36th months showed detectable levels of anti-HBs. There was significant correlation between the produce of anti-HBs in infants and HBsAg-positive at birth while HBsAg-positive and HBeAg-positive in mothers did not relate to the produce of anti-HBs in their infants. Of 39 infants born to HBsAg-positive and HBeAg-positive mothers, 25 showed detectable levels of HBeAg. During the follow-up peirod, HBeAg was still detectable in 2 infants who were also HBsAg positive and the others all became HBeAg-negative but no infant became HBeAg-positive.</p><p><b>CONCLUSION</b>The efficacy of HBIG combining hepatitis B vaccine in high risk infants was fine.</p>

Evaluation on the indirect economic burden of stroke using combination of disability-adjusted life years and human capital method / 中华流行病学杂志

<p><b>OBJECTIVE</b>Using the indirect economic burden of stroke in a rural population to develop rational allocation of future health resources, in Hanzhong area.</p><p><b>METHODS</b>Cluster sampling which involved 53 natural villages with a total number of 75,000 people selected from the 'stroke monitoring base' of rural population was adopted in this study in the Hanzhong area. All of the 164 stroke cases were studied through a self-designed questionnaire. In calculating disability-adjusted life years (DALYs), fixed value was used in accordance with the value of GBD. The disability assessment was simplified in DALYs calculation and modified Barthel's ADL was used in disability assessment of stroke patients. In indirect economic burden analysis, the human capital method combined with DALYs was adopted with the formula as: indirect economic burden = GNP per capita x DALYs x productivity weight.</p><p><b>RESULTS</b>The total DALYs were 598.88, with an average DALY of stroke as 3.65 per case. The total indirect economic burden of stroke patients in rural areas was 1,993,977.8 RMB and the average of indirect economic burden of stroke was 12,158.4 RMB per case with the largest seen in the 45-59 age group, accounted for 74.4%.</p><p><b>CONCLUSION</b>In our study, the use of method in combining the human capital with DALYs was the first time being adopted in calculation of the indirect economic burden of stroke in rural population in China. The burden seemed to be much lower than literature cited from other countries. It was reasonable to evaluate indirect economic burden of stroke using method in integrating DALYs with human capital, but it was difficult to calculate the DALYs.</p>

A retrospective study on the survival rate and risk factors of mortality among 617 inpatients with ischemic stroke / 中华流行病学杂志

<p><b>OBJECTIVE</b>The purpose of this study was to describe survival status and risk factors of mortality on inpatients with ischemic stroke.</p><p><b>METHODS</b>617 patients with continuous ischemic stroke cases were collected from January 2002 to June 2005 retrospectively in the Department of Neurology, Xijing Hospital, Fourth Military Medical University. In order to perceive relevant information on survival and the cause of death. All patients were followed through phone calls or mailing. The follow-up program was completed in January 2006. Kaplan-Meier methods were used for survival description. Monovariant and multivariant Cox's proportional hazard regression model were used to analyze prognostic factors on mortality.</p><p><b>RESULTS</b>The longest time in the follow-up program was 47 months with 59 dropped-out cases, making the dropout rate as 9.5%. Of these patients, 80 cases died during the period of study(60 for ischemic stroke,3 for cerebral hemorrhage, 10 for cardiac disease, 7 for other cause). The median survival time was 42. 16 months. The survival rates of one-year, two-year and three-year period were 91.9%, 89.4% and 85.3%, respectively. Monovariant and multivariant Cox's proportional hazard regression model showed that the risk factors associated with mortality were old age (RR = 1.043, 95% CI: 1.013-1.074), lower Glasgow scores (RR = 0.855, 95% CI: 0.742-0.985) ,poor conscious levels(RR = 4.085, 95% CI: 2.128-7.844) and having complication (RR = 1.765, 95% CI: 1.108-2.812).</p><p><b>CONCLUSION</b>The results of this study suggested that the risk factors were old age, lower Glasgow scores, poor conscious levels and having complication on mortality of ischemic stroke.</p>

In vitro infection of human hepatoma (Hep G2) cell line by hepatitis B virus positive serum / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To establish a culture system of HBV positive serum infected Hep G2 cells in vitro.</p><p><b>METHODS</b>Hep G2 cells were seeded into six-well cluster dishes, at 1 x 10(-6) cells per well and incubated with 3 ml 10% fetal calf serum/ Dulbecco's modified Eagle's medium (10% FCS/DMEM) at 37 degrees in 5% CO2 air. At 24 h after plating, infection group Hep G2 cells were cultured with 0.5 ml HBV positive serum, in control group HBV negative serum was used, 24 h later the inoculums was removed. The cells were then extensively washed with 0.01 mol/L phosphate-buffered saline (PBS). After washing with PBS, 4 ml 2% FCS/DMEM were added to each well and the medium was collected every 12 h. ELISA method was used to detect HBsAg in culture medium. HBV DNA in cells and culture medium was detected by PCR.</p><p><b>RESULTS</b>In infection group, HBsAg could be detected from cell culture medium from 12 h (after PBS washed) to 84 h. HBV DNA could be detected by PCR in culture medium and cells.</p><p><b>CONCLUSION</b>Infection of Hep G2 cells by HBV positive serum is feasible.</p>

Analysis on direct economic burden of stroke in the rural population of Hanzhong, Shaanxi Province / 中华流行病学杂志

<p><b>OBJECTIVE</b>To analyze the direct economic burden of stroke in rural areas of Hanzhong.</p><p><b>METHODS</b>Plan on primary interview was made after the purpose of the study had been informed to the managers of the 'surveillance field base', heads and members of the monitor assistants and detailed information was collected in the fields. Every single patient of stroke was then interviewed by the above said interviewers,using a self-designed questionnaire. 164 patients with stroke were interviewed in 53 villages with 75,000 persons lived there. The main items involved in the questionnaire would include: costs for inpatient or outpatient, reaching-out fees, fee for accommodation during treatment as outpatient, costs for treatment at home, long term medicine, caregivers and funerals as well as average income.</p><p><b>RESULTS</b>The median of annual direct economic burden was 3100 Yuan for each patient in Hanzhong rural area. There were no significant differences seen between males and females or among age groups (P > 0.05). The proportion of patients with medians of annual direct economic burden of: 1000 Yuan and below, 1001-5000 Yuan, 5001-10,000 Yuan, 10,001-20,000 Yuan and over 20,001 Yuan, were 29.2%, 36.0%, 18.3%, 9.8% and 6.0% respectively. The median of annual direct economic burden of first episode stroke was 5500 Yuan for each patient, and that of stroke was 1700 Yuan for each chronic patient. The direct economic burden of first episode was significantly higher than that of stroke (P < 0.01). The costs of hospitalization, accommodation of hospitalization and treatment at home of middle-aged patients were significant higher than that of old age patients (P < 0.05).</p><p><b>CONCLUSION</b>In this study, the direct economic burden of stroke was 2.9 times of the annual personal average income, which was contrary to the reports from other countries. However, the State Health Bureau bore 87.1% of the direct economic burden for urban patients, but patients in the rural areas had to pay from their own pockets. The direct economic burden of stroke was heavy in Hanzhong rural region, which called for measures to be made to decrease the direct economic burden of stroke in the region.</p>

The use of unsupervised classification of Landsat-5 TM images in analysing the types of vegetation in the areas of "breaking dikes or opening sluice for water store" / 中华流行病学杂志

<p><b>OBJECTIVE</b>To clarify the change of vegetation types and its relationship between the density of alive-snails in the areas of "breaking dikes or opening sluice for water store" in Jicheng.</p><p><b>METHODS</b>Synthesized false color images of Jicheng before and after 1998 (1994 and 2003) were classified without supervision and results were compared. Vegetation types were identified on the spot.</p><p><b>RESULTS</b>Normalized difference vegetation index (NDVI) of snail habitats before 1998 were between 126 and 183 in Jicheng, whose vegetation types were mainly paddy, cotton and cabbage. NDVI of snail habitats in Jicheng after 1998 were between 152 and 193 whose vegetation types were mainly poplar forest, bulrush and grass. Areas of snail habitats increased from 64.64% to 66.47%. Snail habitats were mostly composed of mixed vegetation types and mono-typed vegetation was hardly found. According to the density of alive-snails orders from high to low were poplar forest and bulrush, poplar forest and grass, bulrush.</p><p><b>CONCLUSION</b>Vegetation types would not be identified by unsupervised classification only. Poplar forest, bulrush and grass were closedly related to the density of alive-snails.</p>

A retrospective study on the association of sexual behavior during pregnancy with intrauterine infection of hepatitis B virus / 中华流行病学杂志

<p><b>OBJECTIVE</b>Case-control study was employed to explore the association of sexual behavior during pregnancy and hepatitis B virus (HBV) intrauterine infection.</p><p><b>METHODS</b>212 HBsAg positive pregnant women were consecutively collected and investigated as objects. Those neonates detected for HBsAg with S/N value > or = 5 by Abbott reagents in periphery sera were selected as cases, others as controls. Information on sexual behavior during pregnancy, maternal HBeAg status and other factors was collected, and were analyzed with univariate analysis, multivariate logistic regression analysis, etc, to explore the association of factors with HBV intrauterine infection.</p><p><b>RESULTS</b>Ten of the 214 neonates were validated as occurrence of HBV intrauterine infection. Sexual behavior in the second trimester during pregnancy, with odd ratios 9.15 (95% CI: 1.10 - 76.28), as well as maternal positivity for HBeAg and HBV DNA, was significantly associated with HBV intrauterine infection, and sequently affirmed by multiple logistic regression analysis. The strength of association increased with frequency of sexual behavior. Interaction analysis suggested that there was synergistic interaction between maternal positivity of HBeAg and sexual behavior in the second trimester.</p><p><b>CONCLUSION</b>Sexual behavior was a newly discovered risk factor for HBV intrauterine infection, which need to be estimated in future studies. Inhibition of virus replication and moderate control of sexual behavior would be helpful to prevent HBV intrauterine infection.</p>

Analysis on the relationship between malaria epidemics and NOAA-AVHRR NDVI in Hainan province / 中华流行病学杂志

<p><b>OBJECTIVE</b>To explore the relationship between malaria epidemics and NOAA-AVHRR NDVI.</p><p><b>METHODS</b>Data on malaria were collected in all 19 counties in Hainan province from Feb, 1995 to Jan, 1996. Values regarding normalized difference vegetation index (NDVI)-related indicators including mean and maximum values of NDVI, the area proportion of NDVI values of 145- and 145+, months with NDVI values of 135+, 140+, 145+, 150+ of these counties in this period were all extracted from NOAA-AVHRR images, using ERDAS8.5 software. The coefficients of correlation of malaria incidences and these NDVI-related indicator values were then calculated with SPSS 11.0.</p><p><b>RESULTS</b>The incidence of malaria showed positive correlations to mean and maximum values of NDVI, the area proportion of NDVI values of 145+ and months with NDVI values of 135+, 140+, 145+, 150+ respectively, but having negative correlation to the area of NDVI values of 145-. The malaria epidemic regions were in accordance with those regions that the NDVI values of 145+ were continuing for 9 months or more.</p><p><b>CONCLUSION</b>Malaria prevalence was associated with NOAA-AVHRR NDVI value which could be considered to be use for malaria surveillance in Hainan province.</p>

Study on the application of the Chinese version of SF-36 scales and selection of interceptive cents for its grade range / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the possibility of measuring quality of life by Medical Outcomes Study 36-Item Short-Form Health Survey scale and to subdivide grade range of Medical Outcomes Study 36-Item Short-From Health Survey (SF-36) total cents through a Quality of Life questionnaire among the elderly Chinese.</p><p><b>METHODS</b>The quality of life of the 167 elderly Chinese in Suzhou was measured simultaneously by SF-36 and the Quality of Life questionnaire developed by Epidemiology Group of Geriatric Medicine Committee of China for the elderly. Validity and reliability were analyzed and subdivided the grade range of SF-36 total scores by Quality of Life questionnaire for the Chinese elderly.</p><p><b>RESULTS</b>Eight common factors from factorial analysis were in accordance with their theoretical structure, and the cumulative contribution rates of the Quality of Life questionnaire for the elderly and SF-36 were 74.244% and 72.081%. The split-half reliability of the Quality of Life questionnaire for the elderly was 0.6676. The split-half reliability of SF-36 was 0.9384. In SF-36, the Cronbach's alpha coefficient of internal consistency reliability ranged from 0.81 to 0.89, which was satisfactory for group comparison except 0.63 for the social functioning and 0.42 for mental health scale and 0.69 for vitality scale. The Quality of Life questionnaire for old people seemed to have good validity and reliability but the SF-36 was better. The cent of the furthest truncation between the good quality of life and the medium one in the SF-36 was 117 with a Kappa value of 0.58.</p><p><b>CONCLUSION</b>The SF-36 scale could be used for measuring and evaluating the quality of life for the Chinese elderly. The cent of the furthest truncation could provide reference to judge the level of the quality of life of the elderly.</p>

Development and application of geographic information system of Aedes vector in Chaozhou city, Guangdong province / 中华流行病学杂志

<p><b>OBJECTIVE</b>To explore the spatial distribution character of dengue fever and the change of Aedes' population, so as to provide macroscopical decision-making evidences of prevention and supervision on dengue fever.</p><p><b>METHODS</b>(1) Collecting data on morbidity of dengue and supervision on vector's population in the corresponding period. (2) Drawing digitized map of Chaozhou in scale of 1:50,000, including elements of boundary, residential areas, road and traffic, altitude, water systems etc. (3) Measuring the latitude and longitude of center position of surveillance safes on the scene. (4) Processing spatial analysis by the ArcGIS 8.5 software.</p><p><b>RESULTS</b>Distribution of Aedes showed spatial cluster in Chaozhou, while its density was related to the distance to the watersides. The closer to the watersides, the higher the density was. Map on spatial distribution showed that although the Aedes epidemic situation changed yearly, but primarily be kept in high, middle, low regions. Cross-validation effects of the distribution maps were satisfactory.</p><p><b>CONCLUSION</b>Geographic information system was promising in analyzing data on dengue fever, and better than other routine research methods.</p>

Application of "time series analysis" in the prediction of schistosomiasis prevalence in areas of "breaking dikes or opening sluice for waterstore" in Dongting Lake areas, China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To provide the fittest model for forecasting schistosomiasis prevalence in Haokou village of "breaking dikes or opening sluice for waterstore" in Dongting Lake areas by comparing the results of Moving Average, Exponential Smoothing, Autoregressive Model and Autoregressive integrated moving average model (ARIMA model) from 1990 to 2002.</p><p><b>METHODS</b>Error sum of square of four statistical methods was compared and the fittest model was chosen.</p><p><b>RESULTS</b>Error sum of square of predicted schistosomiasis prevalence rates in Haokou village from 1994 to 2002 were 39.40, 39.86, 26.63, 22.54 respectively.</p><p><b>CONCLUSION</b>ARIMA model seemed to be the fittest one in the prediction of schistosomiasis prevalence in Haokou village of "breaking dikes or opening sluice for waterstore" in Dongting Lake from 1990 to 2002.</p>

Meta-analysis on the relationship between tobacco smoking, alcohol drinking and p53 alteration in cases with esophageal carcinoma / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the relationship between tobacco smoking, drinking and p53 alteration in esophageal carcinoma.</p><p><b>METHODS</b>Literature on the relationship between p53 alteration in esophageal carcinoma and tobacco smoking, drinking through Meta-analysis were reviewed.</p><p><b>RESULTS</b>In 14 selected papers related to tobacco smoking, pooled odds ratio (OR) of tobacco smoking with P53 overexpression and p53 alteration were 1.99 (95% CI: 1.30- 3.06) and 1.64 (95% CI: 1.13 - 2.37), respectively (P < 0.05). Pooled OR of tobacco smoking with p53 mutation was 1.11 (95% CI: 0.47 - 2.76) (P > 0.05). In 11 selected papers on alcohol drinking, pooled OR of drinking with P53 overexpression, p53 mutation and p53 alteration were 1.30 (95% CI: 0.83 - 2.04), 1.13 (95% CI: 0.67 - 1.90) and 1.22 (95% CI: 0.87 - 1.72) respectively (P > 0.05).</p><p><b>CONCLUSION</b>There were significant relations between tobacco smoking and p53 alteration while there were no significant relations between alcohol drinking and p53 alteration.</p>

Establishment of minimum medical geographic information systems database in China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To establish a minimum medical geographic information systems (GIS) database as a spatial decision supporting system (SDSS), and to use the database into public health practice in China.</p><p><b>METHODS</b>Spatial data collected from different sources were standardized as decimal degree format, including: (1) satellite images covering areas of China; (2) digital maps of China in vector files; (3) diseases database and relevant models.</p><p><b>RESULTS</b>Necessary satellite images for the database have been collected from NOAA AVHRR, Landsat TM, etc., including the normalized difference vegetation index (NDVI) images from AVHRR, earth surface temperature images from AVHRR, GTOPO30 DEM images from USGS and landuse images from USGS. The digital vector files for GIS analysis were collected including political (county, provinces, country) boundaries file, environmental (drainage, land cover, soil type) vector file, population data and climate data; Data on diseases mainly generated from survey or case reporting. Relevant models on transmission of Schistosoma japonicum and Plasmodium vivax, and models of Oncomelania hupensis and Anophores sinansis were developed, and the relevant environmental factors related to incidence of cancers were mapped, to test and verify those database.</p><p><b>CONCLUSION</b>The database unified the data from different sources for users. Minimum medical data included in the database could be used in the practice of public health. It is expected that this database be used in a wider range.</p>

Study on the relationship between Terra-MODIS image and the snail distribution in marshland of Jiangning county, Jiangsu province / 中华流行病学杂志

<p><b>OBJECTIVE</b>To analyze the relationship between the normalized difference vegetation index (NDVI) and the snail distribution in marshland of Jiangning county in Jiangsu province, and to explore the utility of Terra-MODIS image map in the small scale snail habitats surveillance.</p><p><b>METHODS</b>NDVI were extracted from MODIS image by vector chart of the snail distribution using ArcView 8.1 and ERDAS 8.5 software. The relationship between NDVI and the snail distribution were Investigated using Bivariate correlations and stepwise linear regression.</p><p><b>RESULTS</b>The snail density on marshland was positively correlated with the mean NDVI in the first ten-day of May and the maximum NDVI (N(20max)) in the last ten-day of May. Incidence of pixel with the live snail on marshland was positively correlated with the mean NDVI (N(2mean)) in the first ten-day of May. An equation Y(1) = 0.009 47 x N(20max) (R(2) = 0.73), Y(2) = 0.018 6 x N(2mean) (R(2) = 0.906) was established.</p><p><b>CONCLUSION</b>This study showed that the Terra-MODIS satellite images reflecting the status of the vegetation on marshland in Jiangning county could be applied to the study to supervise the snail habitat. The results suggested that MODIS images could be used to survey the small scale snail habitats on marshland.</p>

Application of satellite image for surveillance of vegetation landscapes of Oncomelenia-snail habitats in marshland using unsupervised classification / 中华流行病学杂志

<p><b>OBJECTIVE</b>To explore the vegetation landscapes in marshland snail habitats using satellite image.</p><p><b>METHODS</b>The false-color composition image from band 2, 3 and 4 of LANDSAT ETM + images was classified in the ERDAS IMAGINE 8.5 to analyze the vegetation types in the marshland of Jiangning county, using the unsupervised classification. The efficiency of classification was evaluated by the transformed divergence. The overlaid layers of the classified vegetation image and the vector layer of snail habitats distribution were used to analyze the relationship between the snail distribution and the landscape types.</p><p><b>RESULTS</b>The land-cover of marshland in LANDSAT ETM234 image in Jiangning county could be classified into 10 types, including water, bare soil, sandy and other landscapes while the transformed divergence analysis showed that there were misclassified pixes between some types especially for the non-continuous types. The study indicated that through adding the NDVI image in the process of classification efficiency of classification and eliminate misclassification in the non-continuous type could be improved. Analysis on the overlaid layer of the vector of snail distribution and the classified image proved that the vegetation covers in marshland snail habitats in Jiangning mainly belonged to type 3, 5 and 6, that responded to the beach with sparse vegetation, exuberant weed and bulrush respectively. The density of snails in the bulrush was higher than that in other 2 landscapes.</p><p><b>CONCLUSION</b>The vegetation type in the marshland snail habitats could be distinguished from the satellite image, which was helpful for the surveillance of snail habitat in marshland and for the prevention of schistosomiasis.</p>

Study on the distribution of malaria in Hainan province through spatial local interpolation technique / 中华流行病学杂志

<p><b>OBJECTIVE</b>To explore the spatial distribution of malaria in Hainan province.</p><p><b>METHODS</b>Maps of spatial distribution on malaria incidence in Hainan province from 1995 to 1999 were produced, using a spatial local interpolation technique in the ArcGIS 8.1 software. Cross-validation techniques were used to evaluate the fitness of the distribution maps.</p><p><b>RESULTS</b>The spatial distribution of malaria in Hainan province from 1995 to 1999 showed that the incidence of malaria in the southern part of Hainan province were higher than that in the north. In the south, the incidence of malaria in east coastal areas were higher than that of other parts, especially in Wuzhi and Yingge mountains. The prediction error of the cross-validation indicated that the spatial distribution maps of malaria in Hainan had good fitness of malaria incidence of Hainan province.</p><p><b>CONCLUSION</b>Spatial local interpolation technique seemed to be promising in describing the spatial distribution of malaria.</p>