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De-zhong Xu

Publications and source records attributed to De-zhong Xu.

At least 19 recordsLinked to original sources
PubMed2006

[Hepatitis B immunoglobulins blocking hepatitis B virus infection of trophoblast cell culture in vitro].

OBJECTIVE: To determine the role of hepatitis B Immunoglobulins (HBIG) in blocking hepatitis B virus (HBV) infection of trophoblast cell culture in vitro. METHODS: Trophoblast cells were placed in the six-well cluster dishes and incubated with 10% fetal calf serum/Dubecco's modified Eagle's Medium (10% FCS DMEM) at 37 degrees C with 5% CO2 in air. At 24 h after plating cells were subjected to experiment. Group A: cells were cultured with 0.5 ml HBV positive serum plus 3 ml 2% FCS DMEM; Group B: cells were cultured with 3 ml 2% FCS DMEM plus 0.5 ml HBV positive serum pretreated with 80 U HBIG for 30 min at 37 degrees C; Group C: cells were cultured with 3 ml 2% FCS DMEM plus 0.5 ml HBV positive serum pretreated with 40 U HBIG for 30 min at 37 degrees C; Group D: cells were cultured with 3 ml 2% FCS DMEM plus 40 U HBIG for 30 min before 0.5 ml HBV positive serum was added; Group E: cells were cultured with 40 U HBIG plus 3 ml 2% FCS DMEM; Group F: cells were cultured with HBV negative serum plus 3 ml 2% FCS DMEM. Twenty-four hours later the inoculums were removed, and the cells were extensively washed with 0.01 mol/L phosphate-buffered saline (PBS). After PBS washing, 4 ml 2% FCS DMEM was added to each well and the medium was collected every 12 hours. Enzyme-Linked Immunosorbent Assay (ELISA) method was used to detect HBsAg in culture medium (absorption value, A). HBV DNA in cell culture medium was detected by polymerase chain reaction (PCR). RESULTS: Before PBS washing, the A value of groups A, B, C, D, E, F were 2.697, 0.040, 0.102, 0.198, 0.036, 0.040 respectively. The cell culture medium in groups of A, B, C, and D were HBV DNA positive, groups of E, F were HBV DNA negative. From 12 hours to 84 hours, the average A value of groups A, B, C, D, E and F was 1.55 +/- 0.27, 0.032 +/- 0.016, 0.100 +/- 0.087, 0.052 +/- 0.044, 0.034 +/- 0.020, 0.034 +/- 0.022 respectively. The A value of groups A was significantly higher than those of other groups (P < 0.01). Cell culture medium at 84 hours of group A was HBV DNA positive and those of group B, C, D, E, F were HBV DNA negative. CONCLUSION: HBIG could effectively block HBV infection of trophoblast cell culture in vitro.

Cells, Cultured↗
PubMed2005

[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"].

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: Vegetation types would not be identified by unsupervised classification only. Poplar forest, bulrush and grass were closedly related to the density of alive-snails.

Animals↗
PubMed2005

[Study on efficacy and safety of lamivudine and interferon-alpha in treatment of hepatitis B virus transgenic mice with pregnancy].

OBJECTIVE: To observe the efficacy and safety of lamivudine and interferon-alpha (IFN-alpha) therapy on decrease of serum hepatitis B virus (HBV) loading of HBV transgenic mice during pregnancy. METHODS: Thirty-five transgenic mice replicating high levels of hepatitis B virus were randomly allocated into 5 groups, each of seven. Pregnant HBV transgenic mice in experimental groups 1 and 2 were given orally lamivudine [100 mg/(kg x d)] from pregnancy day 5 or 10 to delivery, mice in experimental groups 3 and 4 were given intramuscular (im) injection of IFN-alpha [5MU/(m(2) x 2d)], and mice in experimental group 5 were given normal saline at the same times. The changes of serum HBsAg, HBV DNA before and after the treatment were detected. At the same time, eighteen C57BL/6J female mice (clean level) were randomly allocated into control groups 1, 2 and 3 (each group of six), which were given lamivudine, IFN-alpha and saline respectively (the dosage was the same as that of experimental groups). The safety indexes of pregnant mice, fetus and newborns in experimental groups and control groups were observed. RESULTS: (1) The changes of serum HBsAg titers: The average serum HBsAg titers from mice in experimental group 1 were lowered significantly from (166 +/- 98) ng/ml to (82 +/- 59) ng/ml after drug treatment (P < 0.05). Those from mice in experimental group 2 were also reduced from (159 +/- 49) ng/ml to (82 +/- 60) ng/ml after drug treatment, but there was no significant difference between before and after the treatment (P > 0.05). There was no significant difference in serum HBsAg between before and after the treatment in other groups (P > 0.05). (2) The changes of HBV DNA titers: The serum HBV DNA titers from mice in experimental groups 1 and 2 were significantly decreased, from (5.50 +/- 0.86) copies/ml to (2.58 +/- 2.01) copies/ml, with significant difference between before and after the treatment (P < 0.01). Those from mice in experimental groups 3 and 4 were reduced from (5.55 +/- 0.24) copies/ml to (5.46 +/- 0.45) copies/ml, without significant difference between before and after the treatment (P > 0.05). The serum HBV DNA titer from mice in experimental group 5 was not different between before and after the treatment (P > 0.05). (3) Observation of safety indexes: no evidence in toxicity were observed in mice from experimental groups and control groups. No significant abnormalities of live fetus were observed. The postnatal survival and weight of live pups were not different between the groups (P > 0.05). (4) Comparison of the rate of dead fetus and the rate of maternal dead fetus: The rate of dead fetus and the rate of maternal dead fetus from mice in experimental groups 1 and 2 were 8.3% and 50.0% respectively, those from mice in experimental groups 3 and 4 were 8.2% and 66.7% respectively, and those from mice in experimental group 5 were 9.7% and 66.7%. There was no significant difference in the rate of dead fetus and the rate of maternal dead fetus from mice between the groups (P > 0.05). CONCLUSIONS: Effective lamivudine treatment during gestation can reduce hepatitis B viremia in pregnant HBV transgenic mice, thus lowering the risk of intrauterine infection. It has no significant adverse effect on safety of pregnant mice and their offspring.

Animals↗
PubMed2005

[A retrospective study on the association of sexual behavior during pregnancy with intrauterine infection of hepatitis B virus].

OBJECTIVE: Case-control study was employed to explore the association of sexual behavior during pregnancy and hepatitis B virus (HBV) intrauterine infection. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Case-Control Studies↗
PubMed2005

[Analysis on the relationship between malaria epidemics and NOAA-AVHRR NDVI in Hainan province].

OBJECTIVE: To explore the relationship between malaria epidemics and NOAA-AVHRR NDVI. METHODS: 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. RESULTS: 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. CONCLUSION: Malaria prevalence was associated with NOAA-AVHRR NDVI value which could be considered to be use for malaria surveillance in Hainan province.

Animals↗
PubMed2005

[Study on the presence of hepatitis B virus in first-trimester villi in pregnant women with hepatitis B surface antigen positive].

OBJECTIVE: To observe the presence of hepatitis B virus (HBV) in first-trimester villi cells from pregnant women carrying HBsAg. METHODS: Immunohistochemical streptavidin-biotin peroxidase complex (SABC) staining with monoclonal HBsAg, hepatitis B core antigen (HBcAg) and PCR, in situ hybridization were used for detection of HBV infection markers in villi. Positive villi ultramicrostructures were observed with transmission electron microscope. RESULTS: HBV was detected in 8 of 25 villi of HBsAg positive pregnant women, the positive rate was 32%. HBsAg was located in the decidual cell, trophoblastic cell and villous mesenchymal cell. HBV analog was detected in rough endoplasmic reticulum of trophoblastic cell. CONCLUSIONS: HBV may infect villous cells in first-trimester pregnancy. It would be impossible for HBV to transmit the desmosomes.

Chorionic Villi↗
PubMed2005

[In vitro infection of human hepatoma (Hep G2) cell line by hepatitis B virus positive serum].

OBJECTIVE: To establish a culture system of HBV positive serum infected Hep G2 cells in vitro. METHODS: 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. RESULTS: 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. CONCLUSION: Infection of Hep G2 cells by HBV positive serum is feasible.

Carcinoma, Hepatocellular↗
PubMed2005

[Analysis on direct economic burden of stroke in the rural population of Hanzhong, Shaanxi Province].

OBJECTIVE: To analyze the direct economic burden of stroke in rural areas of Hanzhong. METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Age Distribution↗
PubMed2004

[Study on the application of the Chinese version of SF-36 scales and selection of interceptive cents for its grade range].

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Aged↗
PubMed2004

[Development and application of geographic information system of Aedes vector in Chaozhou city, Guangdong province].

OBJECTIVE: 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. METHODS: (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. RESULTS: 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. CONCLUSION: Geographic information system was promising in analyzing data on dengue fever, and better than other routine research methods.

Aedes↗
PubMed2004

[Meta-analysis on the relationship between tobacco smoking, alcohol drinking and p53 alteration in cases with esophageal carcinoma].

OBJECTIVE: To investigate the relationship between tobacco smoking, drinking and p53 alteration in esophageal carcinoma. METHODS: Literature on the relationship between p53 alteration in esophageal carcinoma and tobacco smoking, drinking through Meta-analysis were reviewed. RESULTS: 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). CONCLUSION: There were significant relations between tobacco smoking and p53 alteration while there were no significant relations between alcohol drinking and p53 alteration.

Alcohol Drinking↗
PubMed2004

[Prediction of the spatial distribution of Oncomelania snails in marshland of Jiangning County using the Ordinary Kriging].

OBJECTIVE: To explore the methods to predict the distribution of Oncomelania hupensis in the marshland of Jiangning County. METHODS: Semi-variogram was used to analyze the spatial autocorrelation of snails' distribution in the marshland of Jiangning using the Arcview8.1. A prediction map for the snails' distribution was established using the Ordinary Kriging and evaluated using the cross-validation. RESULTS: Analysis showed that the distribution of alive snails in the marshland of Jiangning in the year 2000 was auto-correlated in spatial. The semi-variogram model which was spherical demonstrated that the variation of alive snails in spatial were related with distance apart when the distance was less than 0.0301. The prediction map of the snail distribution in the marshland of Jiangning was established based on the semi-variogram using the Ordinary Kriging. The cross-validation showed that the prediction map could estimate the distribution of snails in the marshland of Jiangning correctly. And the determinant coefficient for the prediction model was 0.973. CONCLUSION: It is feasible to predict the snail distribution in the marshland of Jiangning County by using Ordinary Kringing and data from the surveillance spot.

Animals↗
PubMed2004

[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].

OBJECTIVE: 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. METHODS: Error sum of square of four statistical methods was compared and the fittest model was chosen. RESULTS: 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. CONCLUSION: 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.

Animals↗
PubMed2003

[HBsAg uptake into human trophoblasts cultured in vitro].

OBJECTIVE: To detect the entry of HBsAg into human trophoblasts cultured in vitro, to provide some clues for the mechanism responsible for HBV intrauterine transmission. METHODS: Digestion with both trypsin (0.25%) and Dnase I(0.15 U/ml) followed by repeated purification was performed to obtain a homogeneous population of trophoblast cells. The well-developed cells during longitudinal phase were randomly divided in 6 groups, which were co-incubated respectively with HBsAg-anti-HBs complex (I), co-culture of heat-inactivated sera positive for HBsAg, HBeAg, and anti-HBc and sera with high titer anti-HBs(II), heat-inactivated sera positive for HBsAg, HBeAg, and anti-HBc(III), HBsAg (IV), heat-inactivated normal sera (V), and normal medium(VI). The coverglasses mounted with confluent cells were harvested for anti-HBs immunohistochemical staining. RESULTS: The isolated cells comprised a highly purified villous trophoblast population and could meet the demands of further experiments. After co-incubation of the cells with different agents, HBsAg test yielded positive results in the cells co-incubated with the HBsAg-anti-HBs complex and in the co-cultures of heat-inactivated sera positive for HBsAg, HBeAg and anti-HBc with sera containing high-titer anti-HBs. HBsAg test was negative in all other cell groups. CONCLUSION: Human trophoblast cells could take in HBsAg in the form of HBsAg-anti-HBs complex instead of single HBsAg molecule.

Antigen-Antibody Complex↗
PubMed2003

[Establishment of minimum medical geographic information systems database in China].

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Animals↗
PubMed2003

[Study on the relationship between Terra-MODIS image and the snail distribution in marshland of Jiangning county, Jiangsu province].

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Animals↗
PubMed2003

[Application of satellite image for surveillance of vegetation landscapes of Oncomelenia-snail habitats in marshland using unsupervised classification].

OBJECTIVE: To explore the vegetation landscapes in marshland snail habitats using satellite image. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Animals↗