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Objective To investigate the prevalence of Schistosoma japonicum infection in wild mice in Shitai County, Anhui Province, so as to provide insights into precise control of the source of S. japonicum infections. Methods Wild mice were captured using the trapping method for three successive nights at snail-infested settings from Jitan Village of Jitan Township, and Shiquan Village and Xibai Village of Dingxiang Township, Shitai County, Anhui Province in June and October, 2018. All trapped wild mice were sacrificed and liver and mesenteric vein specimens were collected for detection of S. japonicum eggs using microscopy, while the fecal samples in mouse intestines were collected for identification of S. japonicum infections using Kato-Katz technique. In addition, the population density of trapped wild mice was estimated and the prevalence of S. japonicum infection was calculated in trapped wild mice. Results A total of 376 wild mice were trapped from three villages in Shitai County. The population density of trapped wild mice was 9.1% (376/4 124), and the prevalence of S. japonicum infection was 24.2% (91/376) in trapped wild mice. The highest prevalence of S. japonicum infection was detected in Shiquan Village of Dingxiang Township (30.1%), and the lowest prevalence was seen in Xibai Village of Dingxiang Township; however, there was no significant difference in the prevalence of S. japonicum infection in trapped wild mice among three villages (χ2= 4.111, P > 0.05). In addition, there was no significant difference in the prevalence of S. japonicum infection in wild mice captured between on June (26.8%, 34/127) and October (22.9%, 57/249) (χ2 = 0.690, P = 0.406). The trapped wild mice included 6 species, including Rattus norvegicus, Niviventer niviventer, R. losea, Apodemus agrarius, Mus musculus and N. coning, and the two highest prevalence of S. japonicum infection was detected in R. losea (34.9%, 22/63) and R. norvegicus (31.2%, 44/141). Conclusions The prevalence of S. japonicum infections is high in wild mice in Shitai County, and there is a natural focus of schistosomiasis transmission in Shitai County.
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OBJECTIVE@#To analyze the spatial-temporal distribution characteristics of Oncomelania hupensis snails in Anhui Province from 2011 to 2020, to provide insights into precision control of O. hupensis snails in Anhui Province.@*METHODS@#O. hupensis snail distribution data were collected in Anhui Province from 2011 to 2020 and descriptively analyzed, including actual area of snail habitats, area of emerging snail habitats and area of Schistosoma japonicum-infected snails. The actual area of snail habitats and area of emerging snail habitats were subjected to spatial autocorrelation analysis, hotspot analysis, standard deviation ellipse analysis and space-time scanning analysis, and the clusters of snail distribution and settings at high risk of snail spread were identified in Anhui Province from 2011 to 2020.@*RESULTS@#The actual area of snail habitats gradually decreased in Anhui Province from 2011 to 2020. The actual area of snail habitats were 26 238.85 hm2 in Anhui Province in 2020, which were mainly distributed in marshland and lake regions. There was a large fluctuation in the area of emerging snail habitats in Anhui Province during the period from 2011 to 2020, with the largest area seen in 2016 (1 287.65 hm2), and 1.96 hm2 emerging infected snail habitats were detected in Guichi District, Chizhou City in 2020. Spatial autocorrelation and hotspot analyses showed spatial clusters in the distribution of actual areas of snail habitats in Anhui Province from 2011 to 2020 (Z = 3.00 to 3.43, all P values < 0.01), and the hotspots were mainly concentrated in the marshland and lake regions and distributed along the south side of the Yangtze River, while the cold spots were mainly concentrated in the mountainous regions of southern Anhui Province. There were no overall spatial clusters in the distribution of areas of emerging snail habitats (Z = -2.20 to 1.71, all P values > 0.05), and a scattered distribution was found in local regions. Standard deviation ellipse analysis showed relatively stable distributions of the actual areas of snail habitats in Anhui Province from 2011 to 2020, which was consistent with the flow direction of the Yangtze River, and the focus of the distribution of areas of emerging snail habitats shifted from the lower reaches to upper reaches of Anhui section of the Yangtze River. Space-time scanning analysis identified two high-value clusters in the distribution of actual areas of snail habitats in lower and middle reaches of Anhui section of the Yangtze River from 2011 to 2020, and two high-value clusters in the distribution of areas of emerging snail habitats were identified in mountainous and hilly regions.@*CONCLUSIONS@#There were spatial clusters in the distribution of O. hupensis snails in Anhui Province from 2011 to 2020, which appeared a tendency of aggregation towards the south side and upper reaches of the Yangtze River; however, the spread of O. hupensis snails could not be neglected in mountainous and hilly regions. Monitoring of emerging snail habitats should be reinforced in mountainous and hilly regions and along the Yangtze River basin.
Subject(s)
Animals , China/epidemiology , Ecosystem , Gastropoda , Lakes , Rivers , Schistosoma japonicumABSTRACT
Objective To analyze the endemic situation of schistosomiasis in national surveillance sites of Anhui Province from 2015 to 2018, so as to provide scientific evidence for schistosomiasis control and prevention in Anhui Province. Methods According to the National Schistosomiasis Surveillance Programme (2014 version), a total of 51 national schistosomiasis surveillance sites were assigned in Anhui Province in 2015, and Schistosoma japonicum infections in humans and livestock and snail distribution were monitored from 2015 to 2018. Results A total of 89 638 local residents and 42 609 mobile populations received serological screening of schistosomiasis in 51 national surveillance sites of Anhui Province from 2015 to 2018, and the sero-prevalence of S. japonicum infections was 1.41% to 3.69% in local residents and 0.84% to 2.13% in mobile populations, respectively. There were 5 egg-positive local residents and 1 egg-positive mobile populations detected in 2015, with occupations of farmers and fishermen. There were 6 405 livestock detected for S. japonicum infections, and no egg-positives were identified. Among an area of 12 661 hm2 surveyed in the national schistosomiasis surveillance sites of Anhui Province from 2015 to 2018, the areas of snail habitats were 2 461.27 to 2 628.96 hm2, andthemeandensityoflivingsnailswas 0.3757 to 0.4330 snails/0.1 m2, with no S. japonicum infections identified in snails. Conclusions The endemic situation of schistosomiasis is at a low level in Anhui Province; however, the risk of schistosomiasis transmission remains in local regions of the province. The construction of the surveillance-responsesystemshouldbereinforcedtoconsolidatetheachievementsofschistosomiasis control in Anhui Province.
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Objective To investigate the spatiotemporal distribution of Oncomelania hupensis snails and infected snails in the endemic areas of schistosomiasis in Anhui Province. Methods Based on the snail survey data in Anhui Province in 2016, the distribution of snails and infected snails were analyzed, and the spatial distribution of snails and spatial cluster patterns of infected snails were investigated in snail habitats in Anhui Province from 1950 to 2016. Results A total of 22 757 snail habitats and 5 004 infected snail habitats were identified in Anhui Province from 1950 to 2016, which appeared single-peak and double-peak patterns, with an inflection point seen in 1970. There were 141 000 hm2 historically accumulative snail habitats, 88.08% of which were firstly identified from 1950 to 1979, and totally 114 500 hm2 snail habitats were eradicated, 77.17% of which were eradicated from 1970 to 1999. There were 4 830 snail habitats identified until 2016, in which 1 051 were once detected with infected snails. In addition, 78.12% of current snail habitats had been present for over 40 years, and infected snails had been eliminated in 65.75% of the infected snail habitats within 10 years. There was a spatial autocorrelation of the living snail density in current snail habitats in Anhui Province (Moran’s I = 0.196, Z = 139.63, P < 0.001), and local hotspot analysis showed spatial clusters of living snails density in snail habitats, with high-value clusters in south of the Yangtze River and low-value clusters in north of the Yangtze River. The 21 high-value clusters of living snail density with statistical significance were distributed along the Yangtze River basin and its branches. Spatiotemporal scan analysis revealed spatiotemporal clusters of infected snails in 4 current snail habitats. Conclusions The current snail habitats have been present for a long period of time, and snails are difficult to be eliminated by chemical treatment alone, which requires the combination of environment improvements. There are spatial clusters of living snail density in current snail habitats in Anhui Province. The epidemic factors and risk of human and animal infections still remain in some clusters of historical infected snail habitats revealed by spatiotemporal scan analysis, which should be consid- ered as the key target areas for snail control in Anhui Province.
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Objective To analyze the endemic situation of schistosomiasis in Wuhu City from 2009 to 2018, so as to provide evidence for adjusting and developing the control strategy. Methods The data regarding the endemic situation were retrospectively collected and analyzed in Wuhu City from 2009 to 2018. Results The prevalence of human Schistosoma japonicum infections reduced from 0.450% in 2009 to 0.035% in 2018 in Wuhu City, and a reduction rate of 92.22% (χ2 = 1 6128.307, P < 0.01), and the prevalence of S. japonicum infections decreased from 0.483% in 2009 to 0 in 2018 (χ2 = 27.570, P < 0.01) in livestock. The area of snail habitats increased from 1 501.07 hm2 in 2009 to 4 408.62 hm2 in 2018, with an increase of 193.70%. No infected snails were found in Wuhu City since 2012, and no egg positives were detected in humans and livestock since 2016. Conclusions Currently, the endemic situation of schistosomiasis is at a low level in Wuhu City; however, there are still factors affecting schistosomiasis transmission. In the future, the integrated strategy with emphasis on the control of infectious source and the surveillance-response system should be intensified to consolidate the achievements of schistosomiasis control.
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Objective To develop a method for designing schistosomiasis surveillance sites, so as to improve the efficiency and quality of schitsosomiasis surveillance. Methods By using the minimum spanning tree-based Spatial Kluster Analysis by Tree Edge Removal (SKATER) method, spatially constrained clustering was performed upon 31 historical schistosomiasis-endemic counties (districts) in Anhui Province. A surveillance site was selected from each cluster to evaluate the representativeness and surveillance efficiency of these cluster-based surveillance sites for the endemic situation of schistosomiassi in Anhui Province, and to compare the surveillance efficiency with local national schistosomiasis surveillance sites. Results There was no significant difference in the environmental factors between the cluster-based schistosomiasis surveillance sites and the whole region, showing a high homogeneity. If the same number of schistosomiasis surveillance sites was selected, there was no significant difference between the cluster-based surveillance sites and national schistosomiasis surveillance sites in the efficiency of the mean risk and long-term trend of schistosomiasis surveillance in Anhui Province; however, the cluster-based surveillance sites were superior to the national schistosomiasis surveillance sites for the prediction and estimation of the endemic situation of schistosomiasis in the unmonitored areas. Conclusion The SKATER-based selection of schistosomiasis surveillance sites may better represent the endemic situation of schistosomiasis in Anhui Province, which may serve as an effective supplement for the conventional method of selecting schistosomiasis surveillance sites.
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Objective To investigate the species and activities of wild animals infected with schistosome in hilly and mountain areas by using an infrared camera technique, so as to provide the evidence for the surveillance of schistosomiasis in these areas. Methods Six infrared cameras were selected and placed in 6 environments of the risk monitoring points of schistosomiasis in Shitai County in Anhui Province. The species and activities of the wild animals in the 6 environments were observed through the photographs and videos taken by the cameras. Results Through 5 day’s monitoring, 3 wild mammals, such as voles, hares and wild boars, were found in 4 monitoring environments, of which voles were found at 2 environments with snails, and hares, wild boars and voles were found in 2 environments adjacent to environments with snails respectively. The monitoring showed that the vole activity was most frequent in the monitored environment. Conclusion The use of infrared camera technique has a good effect in the investigation of wild animal infectious source of schistosomiasis, and it is also suitable for the monitoring work in other types of environments.
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Objective To explore the spatial-temporal clustering distribution of schistosomiasis transmission risk in Yunnan Province from 2004 to 2015, so as to provide scientific evidence for the future schistosomiasis control and consolidation of the control achievements. Methods All data pertaining to endemic situation of human and bovine schistosomiasis and snail survey at a township level in Yunnan Province from 2004 to 2015 were collected. A descriptive epidemiological method and Joinpoint model were used to describe the changing trends of Schistosoma japonicum infections in humans, bovine and snails, and the hotspots and clusters of schistosomiasis transmission risk were identified using spatial autocorrelation analysis, hotspots analysis and retrospective space-time scan statistic in Yunnan Province from 2004 to 2015. Results The prevalence of S. japonicum infections appeared a continuous decline in humans, bovine and snails in Yunnan Province from 2004 to 2015, and the estimated number of schistosomiasis cases reduced from 43 056 in 2004 to 756 in 2015, with a decline rate of 98.24%. There were no acute cases since 2008 and no infected snails since 2014 in Yunnan Province. There were significant differences in the changing trends of human and bovine S. japonicum infections in Yunnan Province between 2012 and 2015 and between 2013 and 2015, respectively using the Joinpoint model (P < 0.05). In addition, there was a spatial autocorrelation in human S. japonicum infections in Yunnan Province from 2004 to 2013 (P < 0.01), and the hotspots areas for human S. japonicum infections were mainly distributed in some townships from Dali City, Weishan County and Eryuan County. Retrospective spatial-temporal scanning revealed that S. japonicum human, bovine and snail infections were clustered in 23, 15, 4 townships from Dali City, Weishan County, Eryuan County, Nanjian County and Heqing County, respectively, with relative risks of 6.25 to 28.75 (P < 0.01), which was almost consistent with the cluster areas detected by hotspots analysis. Conclusions The endemic situation of schistosomiasis significantly reduced in Yunnan Province from 2004 to 2015; however, there is still a risk of schistosomiasis transmission. The monitoring and control of schistosomiasis should be intensified in the future in Yunnan Province.
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Objective To analyze the endemic situation of schistosomiasis in Wuhu City from 2009 to 2018, so as to provide evidence for adjusting and developing the control strategy. Methods The data regarding the endemic situation were retrospectively collected and analyzed in Wuhu City from 2009 to 2018. Results The prevalence of human Schistosoma japonicum infections reduced from 0.450% in 2009 to 0.035% in 2018 in Wuhu City, and a reduction rate of 92.22% (χ2 = 1 6128.307, P < 0.01), and the prevalence of S. japonicum infections decreased from 0.483% in 2009 to 0 in 2018 (χ2 = 27.570, P < 0.01) in livestock. The area of snail habitats increased from 1 501.07 hm2 in 2009 to 4 408.62 hm2 in 2018, with an increase of 193.70%. No infected snails were found in Wuhu City since 2012, and no egg positives were detected in humans and livestock since 2016. Conclusions Currently, the endemic situation of schistosomiasis is at a low level in Wuhu City; however, there are still factors affecting schistosomiasis transmission. In the future, the integrated strategy with emphasis on the control of infectious source and the surveillance-response system should be intensified to consolidate the achievements of schistosomiasis control.
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Objective To develop a method for designing schistosomiasis surveillance sites, so as to improve the efficiency and quality of schitsosomiasis surveillance. Methods By using the minimum spanning tree-based Spatial Kluster Analysis by Tree Edge Removal (SKATER) method, spatially constrained clustering was performed upon 31 historical schistosomiasis-endemic counties (districts) in Anhui Province. A surveillance site was selected from each cluster to evaluate the representativeness and surveillance efficiency of these cluster-based surveillance sites for the endemic situation of schistosomiassi in Anhui Province, and to compare the surveillance efficiency with local national schistosomiasis surveillance sites. Results There was no significant difference in the environmental factors between the cluster-based schistosomiasis surveillance sites and the whole region, showing a high homogeneity. If the same number of schistosomiasis surveillance sites was selected, there was no significant difference between the cluster-based surveillance sites and national schistosomiasis surveillance sites in the efficiency of the mean risk and long-term trend of schistosomiasis surveillance in Anhui Province; however, the cluster-based surveillance sites were superior to the national schistosomiasis surveillance sites for the prediction and estimation of the endemic situation of schistosomiasis in the unmonitored areas. Conclusion The SKATER-based selection of schistosomiasis surveillance sites may better represent the endemic situation of schistosomiasis in Anhui Province, which may serve as an effective supplement for the conventional method of selecting schistosomiasis surveillance sites.
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Objective To explore the spatial-temporal clustering distribution of schistosomiasis transmission risk in Yunnan Province from 2004 to 2015, so as to provide scientific evidence for the future schistosomiasis control and consolidation of the control achievements. Methods All data pertaining to endemic situation of human and bovine schistosomiasis and snail survey at a township level in Yunnan Province from 2004 to 2015 were collected. A descriptive epidemiological method and Joinpoint model were used to describe the changing trends of Schistosoma japonicum infections in humans, bovine and snails, and the hotspots and clusters of schistosomiasis transmission risk were identified using spatial autocorrelation analysis, hotspots analysis and retrospective space-time scan statistic in Yunnan Province from 2004 to 2015. Results The prevalence of S. japonicum infections appeared a continuous decline in humans, bovine and snails in Yunnan Province from 2004 to 2015, and the estimated number of schistosomiasis cases reduced from 43 056 in 2004 to 756 in 2015, with a decline rate of 98.24%. There were no acute cases since 2008 and no infected snails since 2014 in Yunnan Province. There were significant differences in the changing trends of human and bovine S. japonicum infections in Yunnan Province between 2012 and 2015 and between 2013 and 2015, respectively using the Joinpoint model (P < 0.05). In addition, there was a spatial autocorrelation in human S. japonicum infections in Yunnan Province from 2004 to 2013 (P < 0.01), and the hotspots areas for human S. japonicum infections were mainly distributed in some townships from Dali City, Weishan County and Eryuan County. Retrospective spatial-temporal scanning revealed that S. japonicum human, bovine and snail infections were clustered in 23, 15, 4 townships from Dali City, Weishan County, Eryuan County, Nanjian County and Heqing County, respectively, with relative risks of 6.25 to 28.75 (P < 0.01), which was almost consistent with the cluster areas detected by hotspots analysis. Conclusions The endemic situation of schistosomiasis significantly reduced in Yunnan Province from 2004 to 2015; however, there is still a risk of schistosomiasis transmission. The monitoring and control of schistosomiasis should be intensified in the future in Yunnan Province.
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OBJECTIVE To evaluate the impact of the plateau environment on suspended red blood cells (SRBCs). METHODS Plain SRBCs (from healthy people living in Beijing) were stored in Beijing, Lhasa and Linzhi at 4? for 35 and 42 d, respectively. Plateau SRBCs (from healthy people living in Lhasa) were stored at 4? in Lhasa for 35 and 42 d. Hemolysis rate, hemoglobin content, hematocrit and cell survival rate were examined. The extracellular acidification rate of erythrocytes was detected by the extracellular flow analysis technology before baseline glycolsis, glucose response and glycolysis capacity were calculated.RESULTSCompared with the plain SRBCs preserved in Beijing for 35 and 42 d, there was no statistically significant difference in the hemolysis rate, hemoglobin content, hematocrit, cell survival rate, baseline glycolysis, glucose response or glycolysis capacity of SRBCs stored in Lhasa. In SRBCs stored in Linzhi, except the hemolysis rate and glycolysis ability for 35 d(P<0.05), there was no statistically significant difference in other indicators. Compared with plateau SRBCs preserved in Lhasa, after preservation in Lhasa for 35 and 42 d, plain SRBCs had no statistically significant difference in all the indicators above.;CONCLUSION The plateau environment (Lhasa or Linzhi) does not affect the quality of stored SRBCs.
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Objective To investigate the status of Oncomelania hupensis snails in Anhui Province in 2016, so as to provide the evidence for formulating the 13th Five-Year Plans for Schistosomiasis Control. Methods In 2016, a snail survey was conducted in Anhui Province according to the National Programme of the Oncomelania Snail Survey, covering all snail habitats or historical snail habitats and suspected environments of snail breeding, and the results of the survey were analyzed. Results In 2016, 22 848 environments were surveyed, and no schistosome-infected snails were found. There were 17 927 historical snail habitats in whole province, among which, the environments without changes, changed partly and changed completely accounted for 71.2%, 19.3% and 9.5%, respectively. The area of historical snail habitats was 1.410 billion m2. There were 4 830 environments with snail habitats covering an area of 0.265 billion m2 in 38 counties of 7 cities, including newly emerging area of 1 287.65 hm2 and reemerging area of 1 375.32 hm2. The density of living snails was 0.392 0 snails/0.1 m2, and the rate of frame with living snails was 12.93%. The type of marshland and lake regions, and the type of hilly and mountainous regions accounted for 22.4% and 77.6% of number of snail habitats, and accounted for 86.7% and 13.3% of areas of snail habitats, respectively. Among the different types of vegetation in snail habitats, grass was superior owe to accounting for 82.2% of the number of snail habitats, 57.3% of the area with snail habitats, and the highest density of living snails (0.413 9 snails/0.1 m2). Among the different types of environments in snail habitats, the ditch was superior owe to accounting for 56.8% of the number of snail habitats, the highest density of living snails (0.570 3 snails/0.1m2) and the highest rate of frame with living snails (18.57%), and the beach was superior owe to accounting for 87.8% of the area with snail habitats. In Anhui Province, the first year of snails and schistosome-infected snails being found was 1950 and 1952, respectively, and the latest year of schistosome-infected snails being found was 2012. The map showed that the most environments with snail habitats were distributed along the Yangtze River in Anhui Province. Conclusion For the first time, the investigation has built the database and map of snail spatial distribution, which truly reflect the historic and current status of snail distribution in Anhui Province and can provide the evidence for formulating the 13th Five-Year Plans for Schistosomiasis Control and improving the schistosomiasis prevention and control work in the future.
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Objective To investigate the status of Oncomelania hupensis snails in Anhui Province in 2016, so as to provide the evidence for formulating the 13th Five-Year Plans for Schistosomiasis Control. Methods In 2016, a snail survey was conducted in Anhui Province according to the National Programme of the Oncomelania Snail Survey, covering all snail habitats or historical snail habitats and suspected environments of snail breeding, and the results of the survey were analyzed. Results In 2016, 22 848 environments were surveyed, and no schistosome-infected snails were found. There were 17 927 historical snail habitats in whole province, among which, the environments without changes, changed partly and changed completely accounted for 71.2%, 19.3% and 9.5%, respectively. The area of historical snail habitats was 1.410 billion m2. There were 4 830 environments with snail habitats covering an area of 0.265 billion m2 in 38 counties of 7 cities, including newly emerging area of 1 287.65 hm2 and reemerging area of 1 375.32 hm2. The density of living snails was 0.392 0 snails/0.1 m2, and the rate of frame with living snails was 12.93%. The type of marshland and lake regions, and the type of hilly and mountainous regions accounted for 22.4% and 77.6% of number of snail habitats, and accounted for 86.7% and 13.3% of areas of snail habitats, respectively. Among the different types of vegetation in snail habitats, grass was superior owe to accounting for 82.2% of the number of snail habitats, 57.3% of the area with snail habitats, and the highest density of living snails (0.413 9 snails/0.1 m2). Among the different types of environments in snail habitats, the ditch was superior owe to accounting for 56.8% of the number of snail habitats, the highest density of living snails (0.570 3 snails/0.1m2) and the highest rate of frame with living snails (18.57%), and the beach was superior owe to accounting for 87.8% of the area with snail habitats. In Anhui Province, the first year of snails and schistosome-infected snails being found was 1950 and 1952, respectively, and the latest year of schistosome-infected snails being found was 2012. The map showed that the most environments with snail habitats were distributed along the Yangtze River in Anhui Province. Conclusion For the first time, the investigation has built the database and map of snail spatial distribution, which truly reflect the historic and current status of snail distribution in Anhui Province and can provide the evidence for formulating the 13th Five-Year Plans for Schistosomiasis Control and improving the schistosomiasis prevention and control work in the future.
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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 smails positive were important for the schistosomiasis control program to be carried out in Anhui province.
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<p><b>OBJECTIVE</b>To study the current situation and the cause of schistosomiasis resurgence in order to provide reference for formulation of control strategy.</p><p><b>METHODS</b>Data in 1999 - 2003 and baseline data in some areas were collected and analyzed retrospectively.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>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.</p>