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Objective: To study the dynamics of the reinfection of Schistosoma japonicum and related risk factors among the people in schistosomiasis endemic areas in China., Methods: Literature retrieval was conducted by using databases of PubMed, CNKI,VIP and Wanfang to collected all the data about the human re-infection of Schistosoma japonicum and related risk factors in the endemic areas in China. And a Mata-analysis was conducted on the literatures met the inclusion standards., Results: Eighteen studies involving 12 604 people for infection survey and 3 128 people for re-infection survey were included in the analysis. The overall infection rate was 20.8%, and the overall re-infection rate was 21.0% . The difference had no statistical significance (Z = 1.12, P = 0.26). The re-infection related factors included baseline infection intensity (OR = 3.58, 95% CI: 1.56-8.22); the index of contaminated water OR = 2.37, 95% CI: 1.08-5.22); distance from house to river-side (OR = 1.72, 95% CI: 0.41-7.30) and age (OR = 0.48, 95% CI: 0.19-1.23)., Conclusion: The baseline infection intensity, the index of contaminated water and distance from house to river-side were the risk factors related to the re-infection of Schistosoma japonicum and age was a protective factor.

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.

Objective: To explore factors related to current prevention and treatment of Advanced cases on schistosomiasis., Methods: In-depth interviews were introduced to the qualitative study on 61 Advenced cases of schistosomiasis in Dongting Lake regions. Sampling was accidentally and judgmentally performed., Results: Related factors on prevention and treatment of Advenced cases of schistosomiasis would include: higher degree of social support for patients (61/61), excessive dependence on the past pattern of schistosomiasis control, lack of the idea that one should be responsible for his/her own health, lack of knowledge about prevention and treatment of schistosomiasis (28/61), older age (57.40 +/- 10.80), lower education (4.70 years), less family income, lack of effective medical insurance system and efficient close-to-client system., Conclusion: Active participation from patients, medical institutions and society was needed to control Late Stage Schistosomiasis. Health education campaign should be intensified to improve the health awareness for schistosomiasis among residents in the heavy endemic areas. Medical insurance system should be set up in epidemic areas, while public health and cure systems for important diseases should be intensified in rural areas. The ability of public health system to be responsive and the accessibility of residents to health service system should be improved in rural areas as well.

Objective: To study the effect of infection control on schistosomasis Japonicum based on selective chemotherapy., Methods: Data were derived from national surveillance of schistosomiasis from 2000 to 2002, and random effect model of Meta-analysis was used to analyze the effect of chemotherapy on controlling schistosomiasis infection., Results: One year after chemotherapy was started in the pilot villages where infection rate of schistosomiasis was more than 10%, the infection rates among residents and eggs per gram (EPG) of patients as well as population (geometric mean, GM) significantly reduced by 20.15%, 22.91% and 33.93% with 95% confidence interval (CI) 6.95 - 31.48, 14.69 - 30.34 and 11.69 - 50.68 respectively. In the pilot villages where infection rates were between 6% and 10%, the control measures largely base on chemotherapy significantly reduced the infection rate, by 24.50 (95% CI: 5.35 - 39.83). However the infection rates were no longer reduced in the pilot villages where the infection rate was less than 6%; EPG of patients and residents were maintained at the original level in the pilot villages where infection rate was 10% or less., Conclusion: In China, the rates of schistosomiasis Japonicum infection could be effectively reduced through the control measures largely based on chemotherapy, and they were kept at a relatively low level. However, it was very difficult to interrupt the transmission of schistosomiasis.

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.

Objective: To explore the risk factors of Schistosoma japonicum reinfection after chemotherapy in a hilly endemic area., Methods: In a hilly endemic area of S. japonica, data on contact to contaminated water and the rates of reinfection after mass praziquantel treatment were collected from residents who participated in a prospective cohort study on S. japonica. An unconditional logistic regression analysis was performed to identify the risk factors associated with the reinfection of S. japonicum., Results: Logistic regression analysis data showed that three factors were associated with S. japonicum reinfection: eggs per gram stool (EPG) prior to chemotherapy (OR = 2.066, 95% CI: 1.173 - 3.639), gender (OR = 4.260, 95% CI: 1.275 - 14.235) and average degree of exposure (Index B) from April to October (OR = 1.138, 95% CI: 1.045 - 1.240). Interaction between gender and average exposure Index B from April to October was identified (OR = 0.875, 95% CI: 0.817 - 0.982)., Conclusion: Eggs per gram stool (EPG) prior to chemotherapy, level of exposure to infected water and gender were risk factors for reinfection with S. japonicum after chemotherapy. In addition, there appeared an antagonism between gender and level of exposure to infected water.

Objective: To understand the risk factors of schistosomiasis transmission in the Three Gorges Reservoir Area (TGRA) and to provide evidence for the development of control strategy., Methods: Approaches including epidemiology, immunology and field survey were applied to investigate the potential risk factors which would involve the importation of infectious resources live mobile and migrant population, and livestock in the reservoir area. Meanwhile, observation on survival and reproductive status of snail under simulation habitats was also carried out, using ecological methods on snails. Strategy in preventing the spread of snail as infectious resources was also provided., Results: 175 mobile people from schistosomaisis endemic area of were tested and one person showed immunology tests positive with indirect hemagglutination test (IHA) and circumoral precipitin test (COPT), with a positive rate of 0.57%. Through the two-year period under observation, data showed that the snails with ribbon/smooth shells could survive and reproduce under habitats of simulation., Conclusions: Once the infectious resource of schistosomiasis was introduced into the TGRA, the area became a new schistosomiasis epidemic area in TGRA which called for countermeasures to be taken.

Objective: To study the current situation and the cause of schistosomiasis resurgence in order to provide reference for formulation of control strategy., Methods: Data in 1999 - 2003 and baseline data in some areas were collected and analyzed retrospectively., Results: Resurgence was seen in 6.15% (16/260) of the areas and one farm where transmission of schistosomiasis had been interrupted and 33.33% (21/64) of the areas already under control. Snails appeared to have been rebounded only in six counties (farm) while in thirty two counties that rebound was seen in both snails and disease prevalence. Tendency of increase in the total numbers of patients, acute patients and cattle with schistosomiasis, areas with snails were seen from 1999 to 2003., Conclusions: Environmental, ecological, societal factors such as flood, acequia, lack of expenditure and lack of incentives at work etc. contributed to the resurgence of epidemics in those areas that criteria had been reached. Surveillance and supervision on the sources of infection and snail diffusion, especially in the areas where the transmission of schistosomiasis had already been under control.

Objective: To analyze the change of tendency on schistosomiasis epidemics in China in the last 5 years., Methods: Data on schistosomiasis epidemics in the history and particularly in the last 5 years were collected. Tendency and the re-emerging status after 1998 were analyzed., Results: Data in 2003 showed that in 42%, 40% and 53% of the provinces, counties and townships with epidemics, the transmission of the disease has been interrupted or controlled. The number of estimated patients of schistosomiasis and areas with snails were also reduced by 92.74% and 73.56%, in 2003. The annual estimated number of chronic cases was around 800 000 and 31 321.5 hectare of snail infested areas were newly identified in recent 5 years. Among 20 national villages under longitudinal surveillance, 30%, 70% and 35% of the villages were presented a tendency of increase in the rates of human infection, bovine infection and Oncomelania snails infection, respectively. A total of 38 counties from 7 provinces have re-emerged in schistosomiasis transmission after those counties having reached criteria of transmission under control or interrupted. In 6 non-endemic counties, snails were presented, and 16 marshlands in Xan river were found with appearance of acute cases of schistosomiasis. More snail infested areas were found in Shanghai, Zhejiang, and Fujian. Both snail infested areas and newly infected cases were occurred in urban areas along the Yangtze River., Conclusion: The tendency of increase was presented in focal areas along the Yangtze River, due to changes of environmental, ecological, societal and economic status, as well as on the forces of control.

Objective: To analyze the outbreak patterns of acute schistosomiasis in Anhui province in 2003., Methods: The criteria of emergency event for schistosomiasis issued by the Ministry of Health were applled in this study. Epidemiological data of acute schistosomiasis outbreak in Anhui province in 2003 were collected, checked and analyzed., Results: In 2003, there were 6 episodes of acute schistosomiasis outbreaks in Anhui which had met the criteria of being emergency events, issued by the Ministry of Health. The preplanning was initiated in 5 outbreaks to respond to the outbreaks of acute schistosomiasis. All of the acute schistosomiasis cases received timing treatment, except those misdiagnosed cases coming from the non-endemic areas. There were no deaths or follow-up cases during the outbreaks. Health education, preventive treatment for people living in high risk villages were conducted in order to timely control the epidemics of schistosomiasis., Conclusion: The implementation of preplanning has played an important role in early cases-finding, timing report and response to the outbreaks of acute schistosomiasis.

Objective: To study the major risk factors and characteristics of Schistosoma japonicum in the newly identified areas around the Dong Ting Lake., Methods: Data was collected regarding the distribution of snails, prevalence of infection as well as the source of transmission in the newly identified areas in Hunan province from 1979 to 2003., Results: In all the newly identified sites, Schistosomiasis japonica patients appeared to be the first-seen evidence, some even under acute phase. The highest infection rate among residents had reached 87.1% in the newly identified villages. Most of the new endemic areas concentrated in the ditch and beach areas that close to cities and towns., Conclusions: Evidence showed that snails had been transferred through boats and fishing nets to be disseminated. Data also revealed that the sources of transmission would include those local infected residents who had been infected in the old endemic areas and the newly imported domestic animals with infection.

Objective: To assess the potential impact of warming climate in winter to the scale and severity of schistosomiasis epidemics in China., Methods: Based on the data of mean temperature and monthly minimum temperature in January from 126 (out of 733) weather observation stations in China, the trend and oscillation amplitude was analyzed. The impact of warming climate in winter to the scale of schistosomiasis spreading was assessed, using the indices of 0 degrees C mean temperature and -4 degrees C mean monthly minimum temperature in January. Correlation between these two indices was analyzed., Results: Evidences showed the warming climate in winter was seen all over China with the mean monthly minimum temperature and the mean temperature in January had increased 1.3 degrees C and 0.9 degrees C since 1986. The contours of mean monthly minimum temperature -4 degrees C and mean temperature 0 degrees C in January moved 1 - 2 latitudes northward., Conclusion: The warming climate phenomenon seen in winter was considered favorable to the living of snails in winter, resulting in the possible increase of northward spreading of snails.Thus, monitoring of snails should be paid special attention.

Objective: To explore the synthetical index for diagnosing schistosomiasis with ultrasound and to assess the prevalence rate with the index., Methods: Ultrasound indexes of schistosomiasis Japonicum were analyzed by principal component analysis, and the synthetical indexes were assessed by ROC curve., Results: Among the abnormal rates of the 6 indexes, the lowest was 1.6% comparing with the highest of 59.5%. Significant difference was noficed among the abnormal rates (chi(2) = 631.1, P < 0.01). The individual correlation of the six indexes to each other as will as with age distribution was significant (P < 0.05). The three principal components reflected the degree of pathological changes on liver and spleen. The first principal component was the factor reflecting the degree of liver pathological changes, and the second and third principal components reflected the degree of pathological changes on spleen. The synthetical index D(1) = 0.047X(1) + 0.428X(2) + 1.247X(3) + 0.095X(4) + 0.002X(5) + 0.213X(6) - 12.837 was found by adding the three weight principal components, and it's area under the ROC curve was 0.957. When -1.70 was taken as the critical value, the abnormal rate of population was 66.3%, close to the resident's actual prevalence rate 66.9%., Conclusion: Ultrasonography was considered as a method which could rapidly assessing the resident's prevalence rate in the endemic areas of schisitosomiasis Japonicum, and could also provide powerful information for development of strategy on chemotherapy.

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.

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.

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.

Objective: To seek a rapid, simple, but effective inquiry method for screening high risk population challenged by schistosomiasis., Methods: Two embankment collapsed villages were selected in schistosomiasis epidemic area in Dongting Lake. Information on water exposure was collected through a retrospective study. Data was analyzed by stepwise discriminant analysis., Results: A Fisher's function was established by stepwise discriminant analysis which including 5 variables out of 18. Two hundred and forty-six individuals were discriminated by the function with accuracy, sensitivity and specificity of predicting their current infection status with the results of 87.4%, 84.1% and 89.0% respectively., Conclusion: The inquiry method might serve as simple, rapid, economic and effective tool for diagnosis in screening high risk population challenged by schistosomiasis in lake communities.

Objective: To understand the epidemiologic status and geographical distribution of schistosomiasis in China., Methods: Relevant detabases were set up after collection of data from two National Sampling Surveys on Schistosomiasis, in 1989 and 1995. Spatial analysis was undertaken after the database linked to the GIS software which was supported by Arc View 3.0a. Correlation analysis was performed to understand the relationship between rates of human infection and cattle infection., Results: The epidemic areas of schistosomiasis with high risk are mainly distributed in the marshland along the Yangtze River and can be identified as five spatial distribution regions based on the results of spatial analysis. Both epidemic areas and positive rates of stool examination in cattle and water buffalo are much wider and higher than that in humans. The positive correlation was seen between infection rate in human and in cattle from data of both sampling surveys., Conclusion: The relevant strategy for schistosomiasis control in different spatial regions should be performed accordingly and the measures of control for cattle and water buffalo should be strengthened in the endemic areas.

The seroepidemiological data from two schistosomiasis japonica areas with different transmission levels was analysed using a Catalytic Model. The age-specific distribution of IgG antibody in the population of the two investigated settings was analysed with simple catalytic model, the curve equations are Y(A) = 0.876 (1--e-0.048t) and Y(B) = 5.71 (1--e-0.003t) respectively in the heavy- and mild-endemic areas. The age-specific distribution of IgM antibody was analysed with two-stage catalytic model, using a curve equations Y(A) = 2.13 (e-0.032t--e-0.047t) and Y(B) = 0.19 (e-0.012t--e-0.075t) respectively in both heavy-and mild-endemic areas. Based on the result of stool examination concurrently carried out with sera detection and the endemic situation in recent years, the results mentioned above were eligible for the analysis of seroepidemiological data on schistosomiasis to reveal the endemic situation, tendency and the characteristic of age-specific distribution, and in particular using a two-stage catalytic model to analyse IgM antibody. It could also be used for studies on endemic factors, evaluation on the efficiency of control programmes and for surveillance of endemicy.