[Trend analysis of schistosomiasis endemic situation in Anhui Province from 2004 to 2014].

OBJECTIVE: To analyze the changes of schistosomiasis endemic situation in Anui Province from 2004 to 2014, so as to provide the evidence for formulating "The thirteenth five year" schistosomiasis control plan. METHODS: The information for schistosomiasis control and the data of the endemic surveillance of schistosomiasis were collected and analyzed for the changes of schistosomiasis endemic situation in Anhui Province from 2004 to 2014. RESULTS: The Oncomelania hupensis snail areas presented on a rising trend, and reached to the largest area with about 3.1 billon m2in 2011. However, the snail areas decreased from 2012, and reduced by 10.55% in 2012 compared with the areas in 2011, and reduced to the lowest level in 2014 in recent 10 years. The density of living snails presented a fluctuation situation from 2004 to 2008, and on a decreasing trend from 2008, and the density of living snails was below 1 snail/0.l i2 after 2011. The infection rate of snails remained stagnant state from 2004 to 2011, and decreased rapidly in 2012, and no schistosome infected snails were found in 2013 and 2014. The schistosome infection rate of residents decreased gradually, and the number of acute schistosomiasis was under 50 cases with scattered distribution after 2006, and no acute cases occurred in 2013 and 2014. The infection rate of livestock was above 1% from 2004 to 2011, and reduced to 0.55% in 2012, and it was the first time that the infection rate of livestock was lower than that of residents in the same year in 2014. The progress for achieving the goal of schistosomiasis transmission control accelerated after 2011, and the number of counties that reached the standard of schistosomiasis transmission controlled from 2012 to 2014 was 4, 9 and 14 and the number of townships was 33, 76 and 32, respectively. CONCLUSION: Schistosomiasis control has achieved remarkable effectiveness in Anhui Province, but there still exists hard work to consolidate the achievement and reach schistosomiasis transmission interrupted.

[Investigation on endemic situation of schistosomiasis in infection-controlled regions in Anhui Province].

OBJECTIVE: To understand the epidemic situation of schistosomiasis in 27 counties (cities, districts) that reached the criteria of schistosomiasis infection controlled in Anhui Province. METHODS: According to the requirement of The National Assessment Scheme of Schistosomiasis, 81 administrative villages where the schistosomiasis epidemic situation was relatively heaver in above-mentioned 27 counties (1 village per town, 3 towns per county) were sampled and investigated. RESULTS: From 2012 to 2014, 81 villages were investigated, and 34,293 residents received the serum examinations, and 1,086 were positive with a positive rate of 3.17% (0.65%-9.58%), and the positives received stool examinations and the average stool positive rate was 0.37% (0-4.0%). The calculated prevalence of human infection was 0.01%. A total of 3 057 domestic animals were investigated including 438 cattle, 2,550 sheep, and 69 other animals, and no infections were detected. A total of 11,261 living Oncomelania hupensis snails were collected and detected, but no schistosome infected snails were found. Before this investigation, no infected snails were detected for more than 2 years [average 2.3 (2-6) years], and no acute schistosome infection cases were found for more than 2 years [average 4.9 (2-9) years]. CONCLUSION: The infection rates of schistosomiasis in residents and domestic animals are relatively low, and no schistosome infected snails are found in the regions.

Fine scale Spatial-temporal cluster analysis for the infection risk of Schistosomiasis japonica using space-time scan statistics.

BACKGROUND: Marching towards the elimination of schistosomiasis in China, both the incidence and prevalence have witnessed profound decline over the past decades, with the strategy shifting from morbidity control to transmission control. The current challenge is to find out hotspots of transmission risk for precise targeted control in low-prevalence areas. This study assessed the risk at the village level, using the spatial and temporal characteristics of Schistosomiasis japonica in Anhui province from 2006 to 2012. METHOD: The comprehensive database was generated from annual surveillance data at village level in Anhui province between 2006 and 2012, comprising schistosomiasis prevalence among humans and cattle, occurrence rate of infected environments and incidence rate of acute schistosomiasis. The database parameters were matched with geographic data of the study area and fine scale spatial-temporal cluster analysis based on retrospective space-time scan statistics was used to assess the clustering pattern of schistosomiasis. The analysis was conducted by using SaTScan 9.1.1 and ArcGIS 10.0. A spatial statistical modelling was carried out to determine the spatial dependency of prevalence of human infection by using Geoda 1.4.3. RESULT: A pronounced decline was found in the prevalence of human infection, cattle infection, occurrence rate of environment with infected vector snails and incidence rate of acute schistosomiasis from 2006 to 2012 by 48.6%, 71.5%, 91.9% and 96.4%, respectively. Meanwhile, all 4 indicators showed a statistically significant clustering pattern both in time and space, with a total of 16, 6, 8 and 4 corresponding clustering foci found respectively. However, the number of clustering foci declined with time, and none was found after year 2010. All clustering foci were mainly distributed along the Yangtze River and its connecting branches. The result shows that there is a direct spatial relationship between prevalence of human infection and the other indicators. CONCLUSION: A decreasing trend in space-time clustering of schistosomiasis endemic status was observed between 2006 and 2012 in Anhui province. Nevertheless, giving the complexity in schistosomiasis control, areas within the upper-stream of Yangtze River in Anhui section and its connecting branches should be targeted for effective implementation of control strategies in the future.

[Application of space-time scan statistics in early warning of distribution of schistosome infected Oncomelania hupensis snails].

OBJECTIVE: To explore the application of space-time scan statistics in the early warning of distribution of schistosome infected Oncomelania hupensis snails. METHODS: The data of distribution of infected snails in Anhui Province from 2006 to 2012 were collected, and a spatial database was established by ArcGIS 9.3. The prospective spatial-temporal cluster analysis was done by SaTscan 9.1.1 at the village level. RESULTS: Four space-time clusters, which were distributed over the Yangtze River and its branch rivers, were detected. CONCLUSION: The space-time scan statistics could detect the distribution of infected snails early, and the space-time clusters found were the key and difficult points of schistosomiasis control in Anhui Province.

[Spatial-temporal analysis on the distribution of infected snail at the village level in Anhui province, 2006-2012].

OBJECTIVE: The characteristics of spatial-temporal distribution on infected snails were analyzed at the village level in Anhui province, 2006-2012. METHODS: Data on the distribution of infected snails from 2006 to 2012 in Anhui province was collected. Spatial database was established by ArcGIS 9.3. Retrospective spatial-temporal cluster analysis was done by SaTScan 9.1.1 at the village level. RESULTS: Eight areas with increased risk and distributed along the upstream to downstream of Yangtze and connecting branch rivers, were found having infected snails, from 2006 through 2012, including one area in 2006, five in 2006-2008, one in 2007-2009 and one in 2009-2011, respectively. Proportion on the number of areas with infected snails decreased from 6.2% in 2006 to 0.5% in 2012. CONCLUSION: The spatial-temporal distribution of infected snail was not random but there appeared significant clusters. The trend seemed to be declining in Anhui province, between 2006 and 2012. Areas being detected as snails positive were important for the schistosomiasis control program to be carried out in Anhui province.

[Distribution characteristics, trend and control strategy of Oncomelania hupensis snails in Wuhu City from 1997 to 2012].

OBJECTIVE: To understand the emerging and re-emerging trend of Oncomelania hupensis snails in Wuhu City from 1997 to 2012, so as to provide the evidence for developing schistosomiasis control strategy. METHODS: A retrospective survey was conducted. The emerging and re-emerging snail areas were investigated in various years, water systems, settings and countries (districts) based on the historical snail survey results. RESULTS: The accumulative emerging snail area from 1996 to 2007 was 3479.42 hm2, which was mainly found in marshland areas; while the accumulative re-emerging snail area was 1648.08 hm2, which was mainly concentrated on the inland areas. The longest duration from snail re-emergence to snail elimination was 26 years, and the majority of the duration ranged from 3 to 12 years. CONCLUSION: It seems impossible to avoid snail emergence and re-emergence in Wuhu City, which is closely associated with the natural environment and the implementation of schistosomiasis control measures.

[Evaluation on the effect of comprehensive control strategy of schistosomiasis with emphasis on infection source control in Anhui province].

OBJECTIVE: To evaluate the effect of comprehensive control strategy of schistosomiasis with emphasis on infection source control in Anhui province. METHODS: Forty endemic villages in Guichi district, Chizhou city, Anhui province were selected as national pilot villages in the years from 2006 to 2008, and another 10 provincial pilot villages were respectively selected from 10 highly endemic villages in 7 cities in 2007. The comprehensive infection source control measures, including "replace cattle with machines", "raise livestock in pens", "improve the sanitary toilets", "supply safe water " and so on were carried out among the above pilot villages. At the end of 2008, 13 national pilot villages and 6 provincial pilot villages were selected to investigate the popularity of schistosomiasis, and the effect of the comprehensive control strategy in those villages were compared. RESULTS: After implementing the comprehensive control strategy, the infectious rate of schistosomiasis in national pilot villages decreased from 4.57% (487/10 659) to 1.76% (147/8370), with the reduction rate at 61.49%, whose difference showed statistical significance (χ(2) = 115.16, P < 0.01); and the density of infected snails decreased from 0.0067/0.1 m(2) to 0.0008/0.1 m(2), the infectious rate of snails decreased from 0.28% to 0.04%, whose reduction rates were 88.06% and 85.71% respectively. While as to the provincial pilot villages, the infectious rate of schistosomiasis decreased from 1.27% (54/4254) to 0.21% (14/6592), with the reduction rate at 83.46%, whose difference showed statistical significance (χ(2) = 94.57, P < 0.01); and the density of infected snails decreased from 0.0025/0.1 m(2) to 0.0003/0.1 m(2), the infection rate of snails decreased from 0.13% to 0.05%, whose reduction rates were 88.00% and 61.54% respectively. CONCLUSION: The comprehensive control strategy with emphasis on infection source control implemented in marshland and lake regions can effectively control the transmission of schistosomiasis.

[Evaluation of mid-term effectiveness of medium-and-long-term programme for prevention and control of schistosomiasis in Anhui Province].

OBJECTIVE: To evaluate the mid-term effectiveness of the medium-and-long-term programme for prevention and control of schistosomiasis in Anhui Province. METHODS: In the programme, the comprehensive measures were carried out, including the schistosomiasis detection and chemotherapy for residents and livestock, snail control, health education, and infectious source control. The mid-term effectiveness of the programme was observed and evaluated longitudinally. RESULTS: From 2004 to 2009, 750 798 schistosomiasis patients and 547 069 persons with the history of infested water contacting were treated. The number of positive cattle treated was 8 462 cattle-times and the number of cattle with history of infested water contact treated was 117 023 cattle-times. The area with snails control by molluscicides was 30 532.0 hm2, and the area with snails control by environmental modification was 13 979.5 hm2. The number of persons who received health education was 31.73 million person-times. The infectious source control measures were carried out in 40% of endemic villages with human infection rate being more than 1%. Up to 2009, the infection rates of population and cattle, and the incidence rate of acute schistosomiasis reduced to 0.51%, 1.25% and 0.30/100 000, respectively. During the period of 2004-2009, the areas with snails fluctuated from 29 065.4 to 29 740.3 hm2. The densities of living snails and infected snails both showed a declining trend in general. During these years, the whole province reached the criteria of infection control, 4 counties reached the criteria of transmission control, and 4 counties reached the criteria of transmission interruption. CONCLUSION: The effect of the comprehensive strategy of schistosomiasis control is remarkable.

[Spatial analysis of distribution of schistosomiasis in Anhui Province].

OBJECTIVE: To study the distribution of schistosomiasis in Anhui Province based on geographic information system (GIS). METHODS: The survey data of disease and Oncomelania snails in Anhui Province in 2006 were collected, GIS databases were set up, and the inverse distance weighted interpolation method (IDW) based on ArcGIS 9.3 was used to analyze the spatial distribution of schistosomiasis across the province. RESULTS: The simulated maps of distribution of human prevalence and positive rate of serological tests were imitated by using IDW. The region with heavier infection rates of schistosomiasis was distributed over the region of the Yangtze River in Anhui Province, and the endemic areas were joined into a patch in the upper and middle reaches and distributed in pieces in the lower reaches. While the endemic areas were compared with the distribution of infected snails, the IDW map of positive rate of serological tests was more exactly than that of the human prevalence. CONCLUSIONS: The IDW method is helpful to show the distribution of schistosomiasis. The positive rate of serological tests is more sensitive to reflect the current endemic situation of schistosomiasis in Anhui Province.

[Effect of project of afforestation for schistosomiasis prevention on snail control in marshland and lake regions].

OBJECTIVE: To evaluate the effect of the project of afforestation for schistosomiasis prevention on Oncomelania hupensis control. METHODS: The situation of afforestation for schistosomiasis prevention in the field and the snail distribution in marshland regions were surveyed with the systematic sampling method in the spring, 2009. The database of snail distribution was established and the status of afforestation was investigated, and the effect of the project on snail control was evaluated. RESULTS: The rates of frames with living snails in the environment with plantations and the environment without a plantation were 14.9% and 19.7%, respectively, and there was a significant difference (Chi2 = 2 267, P < 0.01). The rate of frames with living snails in agroforestry model was lower than that in other models except for fishery-husbandry-forestry model. The average densities of living snails in the environment with plantations and the environment without a plantation were 0.552 snails/0.1 m2 and 0. 989 snails/0.1 m2, respectively. The average densities of living snails in the cultivating group and un-cultivating group were 0.354 snails/0.1 m2 and 0.653 snails/0.1 m2, respectively. The rate of frames with living snails and the average density of living snails were the lowest in the environment of long-term afforestation. CONCLUSIONS: The project of afforestation for schistosomiasis prevention has a good effect on snail control in Anhui Province. Long-term afforestation could stably maintain the effect on snail control.

[Analysis of trend of Oncomelania snail status in Yangtze River valley of Anhui Province, 1998-2009].

OBJECTIVE: To understand the trend of Oncomelania hupensis snail distribution in Yangtze River valley of Anhui Province so as to provide an evidence for making out schistosomiasis prevention and control strategies in the future. METHODS: The snail data from 1998 to 2009 of the Yangtze River valley in Anhui Province were collected including the snail area, newly occurred and re-occurred snail areas, densities of snails and infected snails, etc., and the trend and influence factors were analyzed. RESULTS: With several fluctuations, the snail area showed a trend of declining in general after the devastating summer flooding in 1998. From 1998 to 2009, 3 peaks of newly occurred snail areas appeared in 1998, 2004 and 2006 and 2 peaks of reoccurred snail areas appeared in 1998 and 2004. The densities of living snails and infected snails were more severe in banks of the Yangtze River than in islets of the Yangtze River. During 12 years, 1 peak of living snail density appeared in 2003, and 3 peaks of infected snail density appeared in 1999, 2003-2004 and 2006 in the islets of the Yangtze River. The densities of living snails and infected snails in banks of the Yangtze both appeared 1 peak in 1998. CONCLUSIONS: The distribution of snails in the Yangtze River valley is related to nature, society and financial circumstances, and it is hard to completely perform the snail control in a short-term. Therefore, at the same time of strengthening snail control, we should also strengthen infectious source control.

[Outbreaks of acute schistosomiasis in Anhui province in 2003].

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.