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Oncomelania hupensis snail control by chemical treatment is an important approach for control and elimination of snails, and an appropriate apparatus for spraying chemicals is an important support to molluscicidal effects. Nevertheless, the research and evaluation of molluscicidal apparatuses have not been paid high attention in the schistosomiasis control programme for a long period of time. Currently, agricultural plant-protective apparatuses have been widely used for chemical treatment. This comment provides a short overview of the application of drones in O. hupensis snail control by chemical treatment, and proposes suggestions for solving the problems of use of drones in O. hupensis snail control by chemical treatment in China.

Objective: To investigate the Oncomelania hupensis snails spread and its spatio-temporal clustering characteristics in Suzhou City, Jiangsu Province from 2016 to 2023, so as to provide insights into precision control of O. hupensis snails in the City., Methods: O. hupensis snail surveillance data in Suzhou City from 2016 to 2023 were collected, and the areas of O. hupensis snail spread and areas of emerging and re-emerging snail habitats were retrieved. The spatial distribution characteristics and clustering types and locations of environments with O. hupensis snail spread were investigated using global and local spatial auto correlation analyses with the software ArcGIS 10.7, and the clustering and cluster areas of O. hupensis snail spread were identified in Suzhou City using spatio-temporal scans with the software SaTScan 10.0.2., Results: O. hupensis snail spread covered an area of 677 171 m 2 in Suzhou City from 2016 to 2023, including 376 230 m 2 emerging snail habitats and 300 941 m 2 re-emerging snail habitats. Global spatial autocorrelation analysis showed overall clustering of O. hupensis snail spread in Suzhou City from 2016 to 2023 (Moran's I = 0.066, P = 0.007), and there were spatial clustering of areas with O. hupensis snail spread in 2019 (Moran's I = 0.086, P = 0.001) and 2021 (Moran's I = 0.045, P = 0.003). Local spatial autocorrelation analysis showed clusters of O. hupensis snail spread in Suzhou City from 2016 to 2023, with high-high clusters in Guangfu Township and Dongzhu Street, and the high-high clusters of O. hupensis snail spread were mainly distributed in southwestern Suzhou City. Spatio-temporal scans identified two clusters of areas with O. hupensis snail spread and areas of re-emerging snail habitats in Suzhou City from 2016 to 2023, with large clustering areas found in Guangfu Township, Dongzhu Street, Tong'an Township and Wangting Township [relative risk ( RR ) = 22.34, log likelihood ratio ( LLR ) = 163 295.32, P < 0.001] and small clustering areas in Xukou Township, Mudu Township and Xiangshan Street ( RR = 2.73, LLR = 921.92, P < 0.001)., Conclusions: There was spatial clustering of O. hupensis snail spread in Suzhou City from 2016 to 2023. Improved quality of O. hupensis snail control and intensified management of environments at a high risk of O. hupensis snail spread are recommended in Suzhou City.

Objective: To investigate the trends in areas of Oncomelania hupensis snail habitats in Anhui Province from 2004 to 2023, so as to provide insights into facilitating the progress of schistosomiasis elimination in the province., Methods: Areas of O. hupensis snail habitats in Anhui Province from 2004 to 2023 were collected, and the trends in and mutations of O. hupensis snail habitats in Anhui Province, and the trends in O. hupensis snail habitats in different types of schistosomiasis-endemic foci and in different cities of Anhui Province from 2004 to 2023 were analyzed using Mann-Kendall test., Results: The areas of O. hupensis snail habitats reduced by 12.62% in Anhui Province in 2023 relative to in 2004. Mann-Kendall trend test showed that the areas of O. hupensis snail habitats appeared a tendency towards a decline in Anhui Province from 2004 to 2023 ( Z = -3.926, P < 0.001, β = -215.66), with an annual average reduction of 215.66 hm 2 . Mann-Kendall mutation test showed that the areas of O. hupensis snail habitats appeared a tendency towards a decline in Anhui Province since 2015 (| Z | > U 0.05 , P < 0.05). The areas of O. hupensis snail habitats appeared a tendency towards a decline in marshland and lake regions ( Z = -4.899, P < 0.001, β = -260.13), and a tendency towards a rise in hilly regions of Anhui Province from 2004 to 2023 ( Z = 2.758, P < 0.01, β = 44.55). Among 9 cities endemic for schistosomiasis in Anhui Province, the areas of O. hupensis snail habitats appeared a tendency towards a decline in 5 cities of Ma'anshan, Tongling, Anqing, Huangshan and Chizhou ( Z = -4.056 to -2.109, all P values < 0.05, β = -92.12 to -0.45). The average constituent ratios of areas of O. hupensis snail habitats were 88.19% and 11.81% in marshland and lake regions and hilly regions of Anhui Province from 2004 to 2023, respectively, and the ratio of areas of O. hupensis snail habitats in marshland and lake regions to areas of snail habitats in hilly regions reduced from 9.23∶1 in 2004 to 5.74∶1 in 2023 in Anhui Province, with the ratio appearing a tendency towards a decline ( Z = -4.477, P < 0.001, β = -0.16)., Conclusions: The areas of O. hupensis snail habitats appeared a tendency towards a decline in Anhui Province from 2004 to 2023, with a reduction in areas of O. hupensis snail habitats in marshland and lake regions and a rise in hilly regions. Targeted O. hupensis snail control interventions are required tailored to real snail status.

Schistosomiasis is a major public health concern in the world, and precision control is crucial to combating this disease. Due to the complex and diverse transmission route of schistosomiasis, conventional statistical models have significant limitations for precision control of schistosomiasis. As an important branch of artificial intelligence, machine learning has shown remarkable advantages in schistosomiasis control and research. It has been shown that machine learning is highly effective for disease prediction and risk assessment, so as to optimize the disease control strategy and resource allocation and achieve the precision control target. This review summarizes the characteristics of machine learning models and their applications in the research of intermediate host snails and schistosomiasis.

Objective: To investigate the capability for distinguishing between the morphology of Oncomelania hupensis and Tricula snails and its influencing factors among schistosomiasis control professionals in Yunnan Province, so as to evaluate the interference of Tricula snails with O. hupensis surveys., Methods: O. hupensis and Tricula snails were sampled from 9 schistosomiasis-endemic counties (districts) in Yunnan Province. The capability for distinguishing between O. hupensis and Tricula snails was evaluated using online questionnaire surveys and field blind tests among schistosomiasis control professionals, and the proportions of correct judgment, misjudgment and missed judgment were calculated. Univariate and multivariate logistic regression models were created using the software SPSS 25.0, and factors affecting the proportion of correct judgments of O. hupensis snails were identified among schistosomiasis control professionals., Results: Questionnaire surveys and field blind tests showed that the overall proportions of correct judgments of O. hupensis snails were 56.77% (2 305/4 060) and 68.28% (1 556/2 279) among schistosomiasis control professionals in Yunnan Province, respectively. Univariate logistic regression analysis of online questionnaire surveys identified gender [odds ratio ( OR ) = 1.244, 95% confidential interval ( CI ): (1.073, 1.441), P < 0.05], professional title [ OR = 0.628, 1.741, 95% CI : (0.453, 0.871), (1.109, 2.734), both P < 0.05], working duration [ OR = 0.979, 95% CI : (0.971, 0.987), P < 0.05] and classification of schistosomiasis epidemics in endemic foci [ OR = 1.410, 0.293, 0.523, 95% CI : (1.103, 1.804), (0.237, 0.361), (0.416, 0.657), all P < 0.05] as factors affecting the proportion of correct judgments of O. hupensis snails among schistosomiasis control professionals in Yunnan Province, and multivariate logistic regression analysis after adjustments showed that the proportion of O. hupensis snail misjudgments was 1.179 times higher among male schistosomiasis control professionals than among females [ OR = 1.179, 95% CI : (1.006, 1.382), P < 0.05], and 1.474 times higher among schistosomiasis control professionals in schistosomiasis-elimination areas with snails than in areas without snails [ OR = 1.474, 95% CI : (1.145, 1.898), P < 0.05], and the proportions of missed judgments of O. hupensis snails were 0.284 [ OR = 0.284, 95% CI : (0.225, 0.359), P < 0.05] and 0.523 times [ OR = 0.523, 95% CI : (0.412, 0.664), P < 0.05] higher among schistosomiasis control professionals in transmission-interruption areas with snails and schistosomiasis-elimination areas with snails than in schistosomiasis-elimination areas without snails. Univariate logistic regression analysis of field blind tests showed age [ OR = 2.381, 95% CI : (1.677, 3.381), P < 0.05], professional title [ OR = 1.688, 95% CI : (1.103, 2.582), P < 0.05］, working duration [ OR = 0.970, 95% CI : (0.956, 0.984), P < 0.05] and classification of schistosomiasis epidemics in endemic foci [ OR = 0.262, 0.593, 95% CI : (0.188, 0.364), (0.420, 0.837), both P < 0.05] as factors affecting the proportion of correct judgments of O. hupensis snails among schistosomiasis control professionals in Yunnan Province, and multivariate logistic regression analysis after adjustments showed the proportions of missed judgments of O. hupensis snails were 0.263 [ OR = 0.263, 95% CI : (0.176, 0.394), P < 0.05] and 0.604 times [ OR = 0.604, 95% CI : (0.416, 0.875), P < 0.05] higher among schistosomiasis control professionals in transmission-interruption areas with snails and schistosomiasis-elimination areas with snails than in schistosomiasis-elimination areas without snails., Conclusions: Schistosomiasis control professionals in Yunnan Province have a low accuracy rate for distinguishing between the morphology of O. hupensis and Tricula snails, and gender and classification of schistosomiasis epidemics in endemic foci are factors that affect their ability to distinguish. The presence of Tricula snails causes a high degree of interference with O. hupensis surveys in O. hupensis snail-infested areas of Yunnan Province. Reinforced training for distinguishing between O. hupensis and Tricula snails is required among schistosomiasis control professionals in Yunnan Province.

Schistosomiasis was once hyper-endemic in Yunnan Province. Following concerted efforts for over 70 years, remarkable achievements have been made for schistosomiasis control in the province. In 2004, the Mid- and Long-term Plan for Schistosomiasis Prevention and Control in Yunnan Province was initiated in Yunnan Province, and the target for transmission control of schistosomiasis was achieved in the province in 2009. Following the subsequent implementation of the Outline for Key Projects in Integrated Schistosomiasis Control Program (2009-2015) and the 13th Five - year Plan for Schistosomiasis Control in Yunnan Province , no acute schistosomiasis had been identified in Yunnan Province for successive 12 years, and no local Schistosoma japonicum infections had been detected in humans, animals or Oncomelania hupensis snails for successive 6 years in the province by the end of 2020. The transmission of schistosomiasis was interrupted in Yunnan Province in 2020. This review summarizes the history of schistosomiasis, changes in schistosomiasis prevalence and progress of schistosomiasis control in Yunnan Province, and proposes the future priorities for schistosomiasis control in the province.

Objective: To investigate the distribution of Oncomelania hupensis snails in different water systems in Anqing City from 2016 to 2022, so as to provide insights into snail control in the city., Methods: Snail survey data and distribution of water systems in snail-infested environments were collected from schistosomiasis-endemic areas of Anqing City from 2016 to 2022. The vector maps of towns and water systems in Anqing City were downloaded from National Geomatics Center of China. The GPS toolbox APP version 2.7.9 was downloaded from a smartphone to record the longitude and latitude of each snail-infested environment in Anqing City, which were loaded into the software LocaSpace Viewer version 4.4.6 to map the distribution of snail-infested environments. The area of snail habitats, area of emerging snail habitats, area of re-emerging snail habitats, type of snail habitats and density of living snails were descriptively analyzed. The spatial database of snail-infested environments in Anqing City was built with the software ArcGIS version 10.8, and the density of living snails was subjected to spatial autocorrelation analysis in snail-infested environments. The hotspot clusters of density of living snails were identified in snail-infested environments and the density of living snails was subjected to standard deviation ellipse analysis in snail-infested environments., Results: A total of 515 snail-infested environments were identified in water systems in Anqing City in 2022. The area of snail habitats reduced from 6 909.32 hm 2 in 2016 to 6 087.48 hm 2 in 2022, with a reduction of 11.89%, and the areas of snail habitats reduced by 2.39%, 21.71% and 1.67% in the main stream of the Yangtze River, the Wanhe River system and the Caizihu River system in Anhui City, respectively, while the area of snail habitats increased by 3.94% in the Huayang River system. Emerging or re-emerging snail habitats were identified in Anqing City each year during the period from 2016 to 2018 and from 2020 to 2020. The density of living snails appeared a tendency towards a decline in the Wanhe River system ( b = -0.030, t = -3.019, P < 0.05) and Huayang River system ( b = -0.029, t = -4.296, P < 0.05) in Anqing City from 2016 to 2022, and fluctuated in the main stream of the Yangtze River ( b = 0.028, t = 1.019, P > 0.05) and the Caizihu River system ( b = 0.020, t = 1.877, P > 0.05). A positive global spatial autocorrelation was identified in the density of living snails in Anqing City each year from 2016 to 2022 (all Moran's I values > 0, all P values < 0.05), and the hotspot clusters of density of living snails in snail-infested environments were mainly distributed in the Wanhe River system (Shankou Township, Hongpu Township, Yueshan Township and Wanghe Townshpi), the main stream system of the Yangtze River (Dalongshan Township, Wanhe Farm, Haikou Township and Huayang Township), the Huayang River system (Dashi Township and Xuqiao Township) and the Caizihu River system (Xiushan Township and Fangang Township). The ratio of the long to short axes of the standard deviation ellipse was 1.72 to 2.06 for the density of living snails in snail-infested environments in Anqing City from 2016 to 2022, and snails were mainly distributed in the southwest to northeast, and appeared the east-west and north-south spread., Conclusions: The areas of snail habitats and the density of living snails appeared a tendency towards a decline in different water systems in Anqing City from 2016 to 2022; however, there is still a risk of snail spread. Reinforced surveillance and precision control of snails are required in Anqing City.

To understand the progress of national schistosomiasis elimination program of China in 2023 and summarize the lessons and experiences, data on the endemic status of schistosomiasis and national schistosomiasis surveillance results in the People's Republic of China were collected and analyzed at a national level. By the end of 2023, Shanghai Municipality, Zhejiang Province, Fujian Province, Guangdong Province and Guangxi Zhuang Autonomous Region continued to consolidate the achievements of schistosomiasis elimination, and Sichuan and Jiangsu provinces maintained the criteria of transmission interruption, while Yunnan and Hubei provinces were identified to achieve the criteria of transmission interruption in 2020, and Anhui, Jiangxi and Hunan provinces achieved the criteria of transmission interruption in 2023. A total of 451 counties (cites, districts) were found to be endemic for schistosomiasis in China in 2023, including 26 250 endemic villages covering 73 034 500 residents at risk of infections. Among the 451 endemic counties (cities, districts), 78.49% (354/451) achieved the criteria of schistosomiasis elimination and 21.51% (97/451) achieved the criteria of transmission interruption, respectively. In 2023, a total of 4 216 643 individuals received immunological tests, with 47 794 sero-positives identified, and a total of 184 216 individuals received parasitological examinations, with 4 egg-positives detected. A total of 27 768 cases with advanced schistosomiasis were documented in China by the end of 2023. In 2023, 539 548 bovines were raised in schistosomiasis-endemic areas of China, and 125 440 bovines received immunological tests, with 124 sero-positives detected, while no egg-positives were identified among the 133 508 bovines receiving parasitological examinations. In 2023, snail survey was performed at an area of 641 339.53 hm 2 and 184 819.77 hm 2 snail habitats were identified, including 51.53 hm 2 emerging snail habitats and 642.25 hm 2 reemerging snail habitats. In 2023, there were 20 198 schistosomiasis patients receiving praziquantel chemotherapy, and 598 183 person-time individuals and 283 954 herdtime bovines were given expanded chemotherapy. In 2023, snail control with chemical treatment was performed in 116 347.95 hm 2 snail habitats, and the actual area of chemical treatment was 65 690.89 hm 2 , while environmental improvements were performed in snail habitats covering an area of 1 334.62 hm 2 . The national schistosomiasis surveillance results showed that the mean prevalence of Schistosoma japonicum infections were both zero among humans and bovines in 2023, and no S. japonicum infection was detected in snails. These data demonstrated that transmission interruption of schistosomiasis had been achieved across all endemic provinces in China in 2023, and the endemic status of schistosomiasis tended to be stable, while advanced cases were predominant among all schistosomiasis cases. However, the areas of snail habitats remained high and cattle re-raising was very common in some regions. Intensified schistosomiasis surveillance and forecast and snail control in high-risk areas are needed.

Objective: To compare the external morphological characteristics and movement patterns between Schistosoma japonicum and S. sinensis cercariae., Methods: S. japonicum and S. sinensis cercariae were heat-fixed, and well-extended cercariae, of 50 each species, were randomly selected for measurement of body length, body width, tail stem length, and tail fork length. The external morphological characteristics of S. japonicum and S. sinensis cercariae were compared. In addition, S. japonicum -infected Oncomelania snails and S. sinensis -infected Tricula snails were observed under a microscope and the movement patterns of S. japonicum and S. sinensis cercariae were compared., Results: The mean body length, body width, tail stem length, and tail fork length were (0.16 ± 0.01), (0.05 ± 0.01), (0.14 ± 0.01) mm and (0.06 ± 0.01) mm for S. japonicum cercariae, and (0.13 ± 0.01), (0.05 ± 0.01), (0.13 ± 0.01) mm and (0.06 ± 0.01) mm for S. sinensis cercariae, respectively, and there were significant differences in terms of cercaria body length ( t = 14.583, P < 0.05) and tail stem length ( t = 3.861, P < 0.05), while no significant differences were seen in terms of body width ( t = 0.896, P > 0.05) or tail fork length ( t = -0.454, P > 0.05). Microscopy revealed that the tails of both S. japonicum and S. sinensis cercariae swung from side to side and there was no significant difference in their movement pattern., Conclusions: S. sinensis and S. japonicum cercariae share highly similar external external morphological characteristics and movement patterns.

Objective: To evaluate the potential risk of transmission of angiostrongyliasis by common freshwater snails in Dali Bai Autonomous Prefecture, Yunnan Province, so as to provide insights into local surveillance of angiostrongyliasis., Methods: Common freshwater snails were collected from Dali Bai Autonomous Prefecture, Yunnan Province from March to April, 2020, and identified and bred in laboratory. SD rats were infected with third-stage larvae of Angiostrongylus cantonensis that were isolated from commercially available Pomacea canaliculata snails in Dali Bai Autonomous Prefecture, and freshwater snails were infected with the first-stage larvae of A. cantonensis that were isolated from the feces of SD rats 39 days post-infection at room temperature. The developmental process and morphological characteristics of worms in hosts were observed, and the percentages of A. cantonensis infections in different species of freshwater snails were calculated. Then, SD rats were infected with the third-stage larvae of A. cantonensis that were isolated from A. cantonensis -infected freshwater snails, and the larval development and reproduction was observed., Results: More than 3 000 freshwater snail samples were collected from farmlands, ditches and wetlands around Erhai Lake in Dali Bai Autonomous Prefecture, and Cipangopaludina chinensis , P. canaliculata , Parafossarulus striatulus , Oncomelania hupensis robertsoni , Galba pervia , Physa acuta , Radix swinhoei , Assiminea spp., Tricula spp. and Bellamya spp. were morphologically identified. A total of 105 commercially available P. canaliculata snails were tested for A. cantonensis infections, and 2 P. canaliculata snails were found to be infected with A. cantonensis , in which the third-stage larvae of A. cantonensis were isolated. Ten species of freshwater snails were artificially infected with the third-stage larvae of A. cantonensis , and all 10 species of freshwater snails were found to be infected with A. cantonensis , with the highest positive rate of A. cantonensis infections in Bellamya spp. (62.3%, 137/204), and the lowest in C. chinensis (35.5%, 11/31). After SD rats were infected with the third-stage larvae of A. cantonensis isolated from different species of freshwater snails, mature adult worms of A. cantonensis were yielded., Conclusions: Multiple species of freshwater snails may serve as intermediate hosts of A. cantonensis under laboratory conditions in Dali Bai Autonomous Prefecture of Yunnan Province. Further investigations on natural infection of A. cantonensis in wild snails in Dali Bai Autonomous Prefecture seem justified.

Objective: To investigate the changes in distribution of Oncomelania hupensis snails in forestlands in Songjiang District, Shanghai Municipality from 2009 to 2023, so as to provide insights into formulation of O. hupensis snail surveillance programs., Methods: The reports on O. hupensis snail surveillance in Songjiang District, Shanghai Municipality from 2009 to 2023 were collected, and the snail surveillance data in forestlands were extracted. The trends in the proportion of areas with snails in forestlands in total areas with snails, occurrence of frames with living snails and density of living snails were evaluated using a Joinpoint regression model in Songjiang District from 2009 to 2023, and the annual percent change (APC) and average annual percent change (AAPC)., Results: A total of 40 sites with snails were found in forestlands in 14 administrative villages of 4 townships, Songjiang District, Shanghai Municipality from 2009 to 2023. A total of 39 065 frames were surveyed for snails in settings covering an area of 609 600 m 2 , and there were 6 084 frames with snails, covering 151 250 m 2 snail habitats. A total of 22 210 snails were captured, with the highest density of 260.00 snails/0.1 m 2 , and 6 262 snails were dissected, with no Schistosoma japonicum infection identified in snails. The proportion of areas with snails in forestlands in total areas with snails appeared a tendency towards a rise in forestlands in Songjiang District, Shanghai Municipality from 2009 to 2023 (APC = AAPC = 24.9%, P > 0.05); however, there were no turning points in the trend curve, with the highest proportion seen in 2009 (53.81%), the lowest in 2011 and 2023 (both 0) and a mean proportion of 24.81%. The occurrence of frames with living snails appeared a tendency towards a rise from 2009 to 2023 (APC = AAPC = 41.5%, P > 0.05); however, there were no turning points in the trend curve, with the highest occurrence in 2009 (53.81%), the lowest in 2011 and 2013 (both 0), and the mean occurrence of 15.57%. In addition, the density of living snails appeared a tendency towards a rise from 2009 to 2023 (APC = AAPC = 55.0%, P > 0.05); however, there were no turning points in the trend curve, with the highest density in 2023 (0.96 snails/0.1 m 2 ), the lowest in 2011 and 2013 (both 0), and a mean density of 0.57 snails/0.1 m 2 ., Conclusions: The difficulty in O. hupensis snail control and risk of imported snails appeared a tendency towards a rise in forestlands in Songjiang District, Shanghai Municipality over years from 2009 to 2023. Supervision and assessment prior to seedling transplantation and intensified surveillance post-transplantation are recommended to reduce the risk of O. hupensis snail importation and spread.

Objective: To analyze the trends in Oncomelania hupensis distribution in Wuhan City, Hubei Province from 2003 to 2022, so as to provide insights into precision schistosomiasis control., Methods: Data pertaining to O. hupensis snail survey in Wuhan City from 2003 to 2022 were collected. The trends in the proportion of areas with snail habitats, actual area with snail habitats, mean density of living snails and prevalence of Schistosoma japonicum infection in snails were evaluated in schistosomiasis-endemic areas of Wuhan City from 2003 to 2022 with the slope of trend curve (β), annual percent change (APC) and average annual percent change (AAPC) using a Joinpoint regression model., Results: During the period from 2003 through 2022, there were two turning points for the proportion of areas with snail habitats in Wuhan City in 2005 and 2015, with a rise during the period from 2003 to 2005 (β 1 = 5.93, t = 1.280, P > 0.05), a decline from 2005 to 2015 (β 2 = -0.88, t = -2.074, P > 0.05) and a rise from 2015 to 2022 (β 3 = 1.46, t = -2.356, P < 0.05). During the period from 2003 through 2022, there were two turning points for the proportion of areas with snail habitats in islet endemic areas of Wuhan City in 2006 and 2015, with no significant differences in the trends from 2003 to 2006 (β 1 = 4.64, t = 1.888, P > 0.05) or from 2006 to 2015 (β 2 = -1.45, t = -2.143, P > 0.05), and with a tendency towards a rise from 2015 to 2022 (β 3 = 2.04, t = -3.100, P < 0.05). During the period from 2003 through 2022, there were two turning points for the proportion of areas with snail habitats in inner embankment endemic areas of Wuhan City in 2012 and 2020, with a tendency towards a decline from 2003 to 2012 (β 1 = -0.39, t = -4.608, P < 0.05) and with no significant differences in the trends from 2012 to 2020 (β 2 = 0.03, t = 0.245, P > 0.05) and from 2020 to 2022 (β 3 = 1.38, t = 1.479, P > 0.05). During the period from 2003 to 2022, the actual area with snail habitats all appeared a tendency towards a decline in Wuhan City, and in islet and inner embankment endemic areas of Wuhan City from 2003 to 2022 (AAPC = -2.39%, -5.75% and -2.35%, all P values < 0.05). The mean density of living snails reduced from 0.087 snails/0.1 m 2 in 2003 to 0.027 snails/0.1 m 2 in 2022 in Wuhan City, with a significant difference in the tendency towards the decline (APC = AAPC = -11.47%, P < 0.05). The annual mean decline rate of the mean density of living snails was 17.36% in outside embankment endemic areas of Wuhan City from 2003 to 2022 (APC = AAPC = -17.36%, P < 0.05), and there was no significant difference in the trends in the mean density of living snails in islet endemic areas of Wuhan City from 2003 to 2022 (APC = AAPC = -0.97%, P > 0.05). In addition, the prevalence of S. japonicum infection in snails appeared a tendency towards a decline in Wuhan City from 2003 to 2022 (APC = AAPC = -12.45%, P < 0.05)., Conclusions: The proportion of areas with snail habitats, actual area with snail habitats, mean density of living snails and prevalence of S. japonicum infection in snails all appeared a tendency towards a decline in Wuhan City from 2003 to 2022. Intensified snail control, modification of snail habitats, shrinking of areas with snails and implementation of grazing prohibition in snail-infested settings are required, in order to facilitate the progress towards schistosomiasis elimination in Wuhan City.

Objective: To analyze the endemic status of schistosomiasis in Suzhou City from 2010 to 2020, so as to provide the evidence for formulating the future schistosomiasis control strategy., Methods: The data pertaining to the endemic status of schistosomiasis in Suzhou City from 2010 to 2020 were retrieved from the annual schistosomiasis control report, the information management platform of schistosomiasis (parasitic diseases) in Jiangsu Province and the Parasitic Diseases Control Information Management System of Chinese Center for Disease Control and Prevention, including snail survey data, snail control data and schistosomiasis examination data, and were retrospectively reviewed. Differences of proportions were tested for statistical significance with chi-square test, and the trends in proportions were evaluated using the chi-square test for trends., Results: Elimination of schistosomiasis was achieved in Suzhou City in 2018, and there were 3.528 9 million residents living in schistosomiasis-endemic villages of 81 townships in 9 counties. A total of 707 600 labor-days were used for snail survey in 11 586 village-times in Suzhou City from 2010 to 2020, covering 18 572.73 hm 2 , and snail habitats were detected with an area of 68.61 hm 2 , including emerging snail habitats of 37.30 hm 2 . A total of 23 144 snails were dissected, and no Schistosoma japonicum infection was detected. Reemerging and emerging snail habitats were predominantly found in inlands. During the period from 2010 to 2020, snail control was performed in Suzhou City for 71 000 labor-times, and snail control was done covering 269.34 hm 2 through chemical treatment and covering 3.48 hm 2 through environmental improvements. A total of 674 002 person-times received serological tests for S. japonicum infections in Suzhou City from 2010 to 2020, with seroprevalence of 0.38%, and a total of 33 835 person-times received stool examinations, with no egg-positives identified. The sero-prevalence of S. japonicum infections appeared an overall tendency towards a rise in Suzhou City from 2010 to 2020 ( χ 2 = 129.48, P < 0.001). The sero-prevalence of S. japonicum infections appeared high among local residents in 2016, and remained stable in other years, while the sero-prevalence of S. japonicum infections appeared an overall tendency towards a rise among mobile populations ( χ 2 = 54.11, P < 0.001). There were 278 800 and 175 202 serological tests among local residents and mobile populations in Suzhou City from 2013 to 2020, and 0.50% and 0.35% sero-prevalence rates were detected, respectively. The sero-prevalence of S. japonicum infections was significantly higher among local residents than among mobile populations in Suzhou City ( χ 2 = 54.76, P < 0.001)., Conclusions: There is a risk of rebound of schistosomiasis in Suzhou City. Integrated control should be reinforced to prevent the risk of rebound of schistosomiasis in Suzhou City.

Objective: To analyze the changing tendency in the endemic situation of schistosomiasis in the national surveillance sites of Hubei Province, so as to provide the scientific evidence for facilitating the progress towards the elimination of schistosomiasis in the province., Methods: According to the National Schistosomiasis Surveillance Scheme (2014 version) , a total of 65 national schistosomiasis surveillance sites were assigned in Hubei Province, and the Schistosoma japonicum infections in humans, domestic animals, snails and wild feces were monitored in these national surveillance sites from 2015 to 2019. All data pertaining to the surveillance results were descriptively analyzed., Results: There were 151 159 person-time local residents and 70 928 person-time mobile populations screened for S. japonicum infections in the 65 national surveillance sites of Hubei Province from 2015 to 2019, and the seroprevalance of S. japonicum infections reduced from 3.45% (1 077/31 197) in 2015 to 1.57% (431/27 371) in 2019 among local residents and from 1.06% (98/9 249) in 2015 to 0.81% (116/14 318) in 2019 among mobile populations. During the period from 2015 through 2019, there were 22 egg-positive local residents and 2 egg-positive mobile populations identified in 2015, with 0.07% and 0.02% prevalence rates of S. japonicum infections, respectively. During the 5-year period, a total of 7 025 herd-time domestic animals examined for S. japonicum infections, with no infections detected, and a total of 2 035 wild feces were tested, with no egg-positives identified in the 65 national surveillance sites of Hubei Province. Snail survey was conducted covering 28 767.35 hm 2 during the 5-year period, and the area of snail habitats ranged from 1 609.82 to 2 119.81 hm 2 . The mean density of living snails and occurrence of frames with snails reduced from 0.360 5 snails/0.1 m 2 and 11.26% in 2015 to 0.175 9 snails/0.1 m 2 and 8.43% in 2019, respectively, and no S. japonicum infection was found in snails during the 5-year period. In addition, no snails were found in the potential schistosomiasis transmission foci in the two national surveillance sites in the Three Gorges Dam., Conclusions: The overall endemic situation of schistosomiasis appears a tendency towards a decline in Hubei Province during the period from 2015 through 2019; however, the schistosomiasis transmission risk remains. Improving the surveillance system of schistosomiasis and increasing the sensitivity and performance of the surveillance system are required to provide insights into the implementation of precision control strategy and interventions in Hubei Province.

This report presented the endemic status of schistosomiasis in the People's Republic of China at a national level in 2019, and analyzed the data collected from the national schistosomiasis prevention and control system and 455 national schistosomiasis surveillance sites. Among the 12 provinces (municipality and autonomous region) endemic for schistosomiasis in China, Shanghai, Zhejiang, Fujian, Guangdong and Guangxi continued to consolidate the achievements of schistosomiasis elimination, Sichuan Province achieved transmission interruption, Jiangsu newly achieved the standard of transmission interruption and 5 provinces of Yunnan, Hubei, Anhui, Jiangxi and Hunan maintained transmission control by the end of 2019. There were 450 endemic counties (cities, districts) endemic for schistosomiasis, including 28 500 endemic villages covering 70 667 800 people at risk of infections. Among the 450 endemic counties (citis, districts), 66.89% (301/450), 28.44% (128/450) and 4.67% (21/450) kept the criteria of elimination, transmission interruption and transmission control of schistosomiasis, respectively. By the end of 2019, a total of 30 170 advanced schistosomiasis cases were documented in China. In 2019, a total of 12 090 712 individuals received inquiry examinations and 1 740 764 were positive; 5 158 369 individuals received serological tests and 89 753 were seropositive. A total of 327 475 individuals received stool examinations and 5 were positive, including one case of acute schistosomiasis. In 2019, snail survey was performed in 19 726 endemic villages in China and Oncomelania snails were found in 7 322 villages, accounting for 37.12% of all surveyed villages, with 6 villages with emerging snail habitats. Snail survey covered an area of 585 286.24 hm 2 and 174 270.42 hm 2 snail habitats were found, including emerging snail habitats of 64.20 hm 2 ; however, no infected snails were identified. In 2019, a total of 605 965 bovines were raised in the schistosomiasis endemic areas of China, and 183 313 received serological examinations, with 1 176 positives detected, while 134 978 bovines received stool examinations, with 7 positives identified. In 2019, there were 28 557 patients with schistosomiasis receiving praziquantel chemotherapy, and expanded chemotherapy was given to 1 008 083 person-times; there were 7 bovines with schistosomiasis receiving praziquantel chemotherapy, and 296 053 herd-times expanded chemotherapy was given to bovines. In 2019, snail habitats at an area of 128 754.26 hm 2 were given chemical treatment, and the actual area of chemical treatment was 69 605.55 hm 2 , while environmental improvements were performed in snail habitats covering an area of 2 847.00 hm 2 . Data from the 455 national schistosomiasis surveillance sites of China showed that the mean Schistosoma japonicum infection rates were both zero in humans and bovines in 2019, and no infected snails were found. The results demonstrate that the overall endemic situation of schistosomiasis remains at a lower infection level in China; however, there is still a risk of schistosomiasis transmission. To achieve the target set in the National Thirteenth Five-Year Plan for Schistosomiasis Control and consolidate the achievements of schistosomiasis control, precision control on schistosomiasis still needs to be reinforced in China.

Objective: To analyze the endemic situation of schistosomiasis in a national surveillance site of Yangzhong City, so as to provide the scientific evidence for adjusting the local schistosomiasis control strategy and consolidating the control achievements., Methods: According to the National Schistosomiasis Surveillance Scheme (2014 version), the snail status, Schistosoma japonicum infections in humans and livestock and wild feces contamination were monitored in Zhinan Village, a national schistosomiasis surveillance site in Yangzhong City from 2015 to 2018., Results: Theareasofsnailhabitatsreducedfrom 8.10 hm 2 in 2015 to 2.72 hm 2 in 2018, and the mean density of living snails decreased from 0.27 snails/0.1 m 2 in 2015 to 0.07 snails/0.1 m 2 in 2018 in Zhinan Village; however, no S. japonicum infections were identified in snails during the period from 2015 to 2018. Serological testing for S. japonicum infections was performed in 2 034 local populations and 858 mobile populations from 2015 to 2018, and the sero-prevalence of S. japonicum human infections was 0.59% to 1.98%, with no egg-positives detected. A total of 79 goats were detected for S. japonicum infections from 2015 to 2018, and no egg-positives were found. In addition, no other livestock was found in Zhinan Village from 2015 to 2018, and no wild feces were found in snail habitats., Conclusions: A great success has been achieved in schistosomiasis control in Yangzhong City; however, there are still snails breeding in the city. Monitoring of the risk factors pertaining to schistosomiasis transmission should be further intensified to consolidate the control achievements.

Objective: To analyze the endemic situation of schistosomiasis in national surveillance sites of Zhenjiang City from 2015 to 2019, so as to provide the scientific basis for the consolidation of schistosomiasis control achievements and timely treatment of risk factors., Methods: A total of 7 national schistosomiasis surveillance sites were assigned in Zhenjiang City from 2015 to 2019. According to the National Scheme for Schistosomiasis Surveillance (2014 version) , Schistosoma japonicum infections were monitored in local residents, floating populations and livestock, and snail habitats were surveyed in Zhenjiang City from 2015 to 2019. The results of schistosomaisis surveillance in Zhenjiang City from 2015 to 2019 were analyzed., Results: There were 15 848 and 7 779 person-times of local residents and floating populations receiving serological screening of schistosomiasis in 7 national surveillance sites of Zhenjiang City from 2015 to 2019, and the seroprevalence rates were 0.95% to 1.75% and 0.14% to 0.91% among local residents and floating populations, respectively; however, no egg-positives were identified. A total of 1 885 herd-times of livestock were detected, and no egg-positives were found. During the 5-year period, snail survey was conducted in snail habitats and suspected snail habitats covering 3 333.79 hm 2 , and there were 108.71 hm 2 snail habitats identified, including 50.97 hm 2 re-emerging snail habitats. The density of living snails was 0.007 to 0.125 snails/0.1 m 2 from 2015 to 2019, which showed a trend for a rise year by year ( χ 2 = 2 732.626, P < 0.01); however, no S. japonicum infections were detected in snails., Conclusions: The endemic situation of schistosomiasis has been maintained at a low level in Zhenjiang City, and schistosomiasis control achievements are consolidated. However, snails are widely distributed in the city, and there are still risk factors associated with schistosomiasis transmission. Further integrated interventions require to be reinforced to timely manage the risk of transmission of schistosomiasis and promote the progress towards elimination of schistosomiasis.

Objective: To assess the schistosomiasis transmission risk in Nanjing County, so as to provide the scientific evidence for the development of the schistosomiasis control strategy and consolidation of the control achievements., Methods: On May 2019, the Deqiu Village in Deqiu Town and Baiyun Village in Nanjing Town of Yunnan Province, where schistosomiasis were historically relatively highly endemic, were selected to assess the risk of transmission of schistosomiasis by means of a retrospective review of the data pertaining to the historical endemic situation and schistosomiasis control, combined with a cross-sectional survey of snail and wild feces distribution., Results: During the period between 2017 and 2018, the mean sero-prevalence rates of Schistosoma japonicum infections were 6.76% (202/2 990) and 2.86% (142/4 971) in humans and 0 (0/1 160) and 10.65% (31/291) in bovines in Deqiu and Baiyun villages of Nanjian County, respectively; however, no egg-positives were identified; in addition, there were 21.06 hm 2 snail habitats found, but no S. japonicum infections were detected in snails. In 2019, there was 6.17 hm 2 snail habitats detected, with 2.17% (245/11 298) occurrence of frames with snails and a 0.06 snails/0.1 m 2 density of living snails; however, no positives for nucleic acid detection were seen in snails; among the 136 wild fecal samples captures from 23 settings, no S. japonicum infections were identified., Conclusions: The risk of schistosomiasis transmission remains at a low level in Nanjian County; however, the factors affecting the transmission of schistosomiasis have not been completed eliminated. The integrated schistosomiasis control strategy with an emphasis on the control of the source of S. japonicum infections requires to be reinforced to consolidate the control achievements.

Currently, the endemic situation of schistosomiasis has dropped to the lowest level in China; however, there are still factors affecting the transmission of schistosomiasis. Flood disasters may pose a great impact on the transmission of schistosomiasis and even affect the progress of schistosomiasis control and the consolidation of schistosomiasis control achievements. In 2020, major flood disasters occur across China. This paper analyzes the current status of schistosomiasis and the impact of flood disasters on the transmission of schistosomiasis in China, and systematically describes the assessment of and response to schistosomiasis transmission risk before flood disasters, the prevention of Schistosoma japonicum infections during flood disasters and the assessment of the endemic situation of schistosomiasis and surveillance of schistosomiasis after flood disasters. It is considered that schistosomiasis control is an important part of conventional schistosomiasis control activities and an important part of anti-flood and schistosomiasis-preventive activities in flood disaster-affected areas. It is recommended that emergence response interventions are implemented in a scientific and well-organized manner to avoid or reduce the risk of schistosomiasis transmission caused by flood disasters. In addition, the research on early surveillance and forecast approaches for schistosomiasis should be emphasized and reinforced to provide the scientific and precise tools for achieving the goal of the 13th Five-year Plan for Schistosomiasis Control and elimination of schistosomiasis in China.

Objective: To investigate the implementation of schistosomiasis control activities in China during the coronavirus disease 2019 (COVID-19) epidemic, so as to evaluate the impact of COVID-19 epidemic on the national schistosomiasis control program in China., Methods: On April 2020, 3 counties (districts) were randomly selected from each of the 12 schistosomiasis-endemic provinces (municipality, autonomous region), and a questionnaire survey was conducted to investigate the implementation of schistosomiasis control activities in these counties (districts) from January to March 2020. Then, the impact of the COVID-19 epidemics on the national schistosomiasis control program of China was evaluated using a comparative analysis approach., Results: Among the 36 counties (cities, districts) sampled from 12 provinces (municipality, autonomous region), 66.67% were at a high and medium risk of COVID-19 epidemics. The implementation of schistosomiasis control activities assignment, human schistosomiasis examination and treatment, snail control with chemical treatment and health education reduced by 44.26% to 91.56% as compared to 2019 during the same time period, and the schistosomiasis control program was more affected by COVID-19 in transmission-controlled provinces. The gross funds invested into the schistosomiasis control program reduced by 23.39% in relative to the expected, while the total expenditure increased by 41.22%. In addition, all 36 surveyed counties (districts) considered that the COVID-19 epidemic had a short-term impact on the schistosomiasis control program, with the most predominant impact on schistosomiasis control activities assignment, human resources and monitoring of endemic situation of schistosomiasis., Conclusions: The COVID-19 epidemics affect the routine schistosomiasis control program across the endemic-foci of China. Policy and financial support should be strengthened to ensure the completion of the schistosomiasis control program.

Objective: To investigate the spatio-temporal distribution characteristics of Oncomelania hupensis snail habitats in three cities of Suzhou, Wuxi and Changzhou along the Taihu Lake region, so as to provide technical supports for establishing a sensitive and highly effective surveillance and forecast system for schistosomiasis., Methods: Snail distribution data were collected from Suzhou, Wuxi and Changzhou cities from 1950 to 2018, and the changing trend for snail habitats were described over years. In addition, the clusters of snail habitats were detected using Kernel density analysis and SaTScan space-time scan analysis., Results: The number of snail habitats appeared a single-peak distribution in Suzhou, Wuxi and Changzhou cities from 1950 to 2018, which peaked in 1970 and then declined rapidly. There were 62.68% of snail habitats eliminated within 10 years after identification, of which 38.24% were eliminated at the year of identification. Kernel density analysis and SaTScan space-time scan analysis revealed that high-density clusters of snail habitats were mainly distributed in Kunshan City, Wuzhong District and Xiangcheng District from 1970 to 1980, and in Yixing City in 1990; since then, the clusters gradually shrank, and overall appeared a move from northeast to west of Taihu Lake. A total of 4 new clusters were detected after 1970, as revealed by space-time scanning of snail habitats. In current snail habitats, emerging snail habitats are mainly identified in Huqiu District (Dongzhu Town), Wuzhong District (Guangfu Town), Taicang City (Shaxi Town) and Jintan District, and re-emerging snail habitats are scattered in 7 districts., Conclusions: The distribution of snail habitats are spatio-temporal aggregation in Suzhou, Wuxi and Changzhou cities. The monitoring and prediction of emerging and re-emerging snail habitats are the key points in the future.

Objective: To evaluate the effectiveness of Oncomelania snails control following the implementation of integrated schistosomiasis control measures in river channels connecting the Yangtze River in endemic areas of Nanjing City., Methods: The river channels connecting the Yangtze River with snails in Nanjing City were selected as the study pilots. The integrated schistosomiasis control measures implemented in the study pilots were investigated by means of retrospective analyses and field surveys from 1998 to 2019, and the effectiveness of snail control was evaluated., Results: Integrated control measures with emphases on environmental improvements including water resource projects for schistosomiasis control were implemented in the study pilots during the period from 1998 to 2019, including river bank concretion with 84.51 km in length, marshland cutting and dredging with 50.41 km in length, building 2 sluices and 3 overflow dams, digging one floodway and snail control with chemical treatment that covered an area of 3 370.80 hm 2 . No Schistosoma japonicum infection had been detected in snails since the completion of the integrated control measures. In addition, snails had been eliminated in 6 river channels connecting the Yangtze River until 2019, with the snail habitats reducing from 214.33 hm 2 to 52.22 hm 2 in 10 river channels connecting the Yangtze River and the snail density reducing to below 0.1 snails/0.1 m 2 in snail-breeding river channels connecting the Yangtze River., Conclusions: The integrated schistosomiasis control measures with emphases on environmental improvements may effectively control snail breeding and spread in rivers connecting the Yangtze River in endemic areas of schistosomiasis; however, the maintenance of the project and snail surveillance and control should be intensified following the completion of the integrated schistosomiasis control measures.

Objective: To investigate the distribution of Oncomelania snails in Four-Lake Basin of Hubei Province, so as to provide scientific evidence for the development of snail control interventions., Methods: The snail distribution was surveyed by means of the retrospective study and cross-sectional survey in the Four-Lake Basin in Spring of 2016. The data pertaining to the endemic situation of schistosomiasis were collected and analyzed in the Four-Lake Basin from 2008 to 2018, and the associations of snail habitat areas with the prevalence of Schistosoma japonicum in humans and bovines were examined., Results: There were 16 003 snail habitats in the 9 schistosomiasis-endemic counties (districts) in the Four-Lake Basin in 2016, covering an area of 246 million m 2 . The mean density of living snails was 0.622 5 snails/0.1 m 2 , which was relatively high in weed-type settings (0.688 0 snails/0.1 m 2 ) and ditches (0.706 4 snails/0.1 m 2 ). Type I (current snail habitats, 53.03%) and Ⅱ- Ⅳ (historical snail habitats, 46.97%) settings were predominant snail habitats. A big change was seen in snail habitats in dry farmland, marshland and paddy farmland, and environmental modification resulted in satisfactory snail control effectiveness. In addition, the area of snail habitats positively correlated with the changes in the prevalence of S. japonicum infections in humans ( r = 0.842, P < 0.01) and livestock ( r = 0.695, P < 0.01)., Conclusions: The integrate strategy with an emphasis on the control of the source of S. japonicum infections results in remarkable snail control effectiveness in the Four-Lake Basin; however, there is a risk of re-emerging snail habitats.

Hunan Province occupies a particular position in the history of the national schistosomiasis control programme of China. The province is hyperendemic for schistosomiasis, and achieves great successes and many experiences at various stages of the national schistosomiasis control programme of China. Recently, remarkable schistosomiasis control benefits have been achieved in Hunan Province because of the strong political will, increased financial support, intensification of the integrated control strategy and sustainable implementation of the four projects, including management of livestock and humans as sources of Schistosoma japonicum infections, snail control and capability building of schistosomiasis control institutions. In addition, a series of schistosomiasis control models have been created from the schistosomiasis control programme, and the concept of control-research combination and research serving for field control has been achieved, which provides the "Hunan experience" for the natonal schistosomiasis control programme of China. Based on the government-led multisectoralcollaboration principle, further actions are required with scientific control and joint prevention and control, implementation of the integrated strategy with emphases on controlling sources of S. japonicum infections and snails, adequate financial support, improved professional capability building, and innovative medical treatment-prevention combination patterns, so as to achieve the goal of schistosomiasis elimination in Hunan Province as soon as possible.

Objective: To analyze the changes in the endemic situation of schistosomiasis in national surveillance sites of Hunan Province, so as to provide scientific basis for the development of the schistosomiasis elimination programme in the province., Methods: According to the requirements of the National Guidelines for Schistosomiasis Surveillance in China (2014 version), a total of 41 national schistosomiasis surveillance sites were assigned in all disease-endemic counties (districts) across Hunan Province. During the period between 2015 and 2019, Schistosoma japonicum infections were monitored in local residents, mobile populations and livestock, and snail status was monitored. The morbidity due to schistosomiasis and snail status was compared between years., Results: The sero-prevalence of S. japonicum infections was 2.57% and 1.56% in local residents and mobile populations in national surveillance sites of Hunan Province from 2015 to 2019, respectively, and the sero-prevalence appeared a tendency towards a decline over years. A higher sero-prevalence rate of S. japonicum infections was seen in men than in women ( P < 0.01). During the 5-year study period, the sero-prevalence rate of human S. japonicum infections appeared a tendency towards a decline in the marshland, embankment, inner embankment and hilly types of endemic areas over years. There were 44 and 19 egg -positives detected in local residents and 5 and 1 egg-positives in mobile populations in 2015 and 2016 respectively. A total of 9 346 domestic animals were monitored from 2015 to 2019, and 6 egg-positives were detected in 2015 and 2016 (all were bovine). A total of 0.155 billion m 2 settings were surveyed from 2015 to 2019, and the mean density of living snails appeared a tendency towards a decline over years, with a 45.79% reduction in 2019 as compared to 2015. However, no S. japonicum infections were identified in snails during the 5-year period. A total of 1 469 mixed snail samples were detected using loop-mediated isothermal amplification (LAMP), and 6 positive snail samples were identified in 2015 (one sample) and 2017 (5 samples)., Conclusions: The overall endemic situation of schistosomiasis appears a tendency towards a decline in Hunan Province, and the prevalence of S. japonicum infections is at a low level in humans and livestock; however, there is still a risk of schistosomiasis transmission. Improvements of health education, intensification of schistosomiasis examinations in mobile populations and reinforcement of the surveillance-response system is required to consolidate the achievements of schistosomiasis control in Hunan Province.

Objective: To examine the effect of the integrated schistosomiasis control measures in Hunan Province from 2004 to 2019, so as to provide insights into the development of the schistosomiasis elimination strategy., Methods: The integrated schistosomiasis control measures implemented by the health, agriculture, water resources, forestry, land and resources sectors were retrospectively collected in Hunan Province from 2004 to 2019, and the completion of each measure, cost of control measures, Schistosoma japonicum infections in humans and bovines, and snail status were analyzed each year. An index system for assessing the integrated schistosomiasis control effect was constructed using the Delphi method to calculate the integrated schistosomiasis control effect index. In addition, a cost-effect analysis was performed in terms of the decline in the prevalence of S. japonicum infections in humans and bovines, areas with snails in inner embankments, and areas with infected snails., Results: A total of 7 110 926 500 Yuan were invested into the integrated schistosomiasis control program of Hunan Province from 2004 to 2019. During the 16-year period, a total of 277 437.12 hm 2 snail habitats received molluscicidal treatments, 6 927 230 person-times given expanded chemotherapy, 2 116 247 bovine-times given expanded chemotherapy, 954 850 harmless toilets built, 290 359 bovines fenced, 136 666 bovines eliminated, 141 905 machines used to replace bovines, 39 048.63 hm 2 water lands improved as dry lands, 724.12 km irrigation regions improved, 3 994 300 populations covered with safe water, 191 102.89 hm 2 forests planted and 38 535.27 hm 2 lands leveled. The prevalence of S. japonicum infections was 4.29% in humans and 4.48% in bovines in Hunan Province in 2004, with 2 449.37 hm 2 snail habitats in inner embankments and 3 423.74 hm 2 infected snail areas. In 2019, the prevalence of S. japonicum infections reduced to 0 in both humans and bovines, and areas of snail habitats reduced to 540.92 hm 2 (77.92% reductions), while the areas with infected snails reduced to 0. The overall integrated schistosomiasis control effect index appeared a tendency towards a rise over years since 2004, and the integrated schistosomiasis control effect index was 97.35 in 2019; the annual mean costs for a 1% reduction in the prevalence of S. japonicum infections in 100 populations and 100 bovines were 70.11 Yuan and 4 204.78 Yuan, and the annual mean costs for a 1% reduction in the snail areas in inner embankments and infected snail areas were 2 010.20 Yuan and 1 298.09 Yuan, respectively., Conclusions: The integrated control measures achieve remarkable effectiveness for schistosomiasis control in Hunan Province, with a remarkable decline in the prevalence of S. japonicum infections in humans and bovines and great shrinking of snail areas in inner embankments and infected snail areas. Adequate fund investment is required to improve the integrated schistosomiasis control measures and consolidate the control achievements.

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 hm 2 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 hm 2 , andthemeandensityoflivingsnailswas 0.3757 to 0.4330 snails/0.1 m 2 , 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.

Objective: To analyze the endemic situation of schistosomiasis in Hunan Province in 2019, so as to provide insights into the achievement of transmission interruption of schistosomiasis in the province in 2020., Methods: The data pertaining to Schistosoma japonicum infections in humans and livestock and snail status were captured from Hunan Province in 2019 and analyzed., Results: Schistosomiasis was endemic in 281 townships (towns) from 41 counties (districts) of 6 cities in Hunan Province by the end of 2019. A total of 991 900 persons received blood testing in Hunan Province in 2019, and 22 773 were positive for the blood testing, with sero-prevalence of 2.30%. All stool examinations were negative in 22 933 individuals detected. The high sero-prevalence was seen in Nanxian County, Anxiang County and Ziyang District. Currently, there were 5 034 cases with advanced schistosomiasis detected in Hunan Province, and they were predominantly identified in Yuanjiang City, Heshan District and Yueyang County. There were 44 963 bovines fenced in schistosomiasis-endemic villages in Hunan Province in 2019, which were predominantly distributed in Yuanjiang City, Hanshou County and Ziyang District, and no positives were detected in 1 996 bovines receiving blood testing or 20 684 bovines receiving stool examinations. In 2019, there were snail habitats of 1.73 billion m 2 found in Hunan Province, which were mainly found in Yuanjiang City, Hanshou County and Yueyang County., Conclusions: The endemic situation of schistosomiasis further decreases in Hunan Province in 2019; however, there is still a risk of schistosomiasis transmission in local areas of the province.

As an ancient parasitic disease, schistosomiasis has been endemic in Dongting Lake areas for more than 2 100 years. In the early 20th century, the first human case of schistosomiasis in China was reported in Dongting Lake areas, which was paid extensive attention. After the founding of the People's Republic of China, large-scale schistosomiasis control activities were launched promptly in Dongting Lake areas, and great successes have been achieved following the three stages of control efforts, including the snail control-based stage, synchronous chemotherapy for humans and livestock-based control stage and infectious source control-based control stage. In 2015, transmission control of schistosomiasis was achieved in Hunan Province. This paper comprehensively describes the discovery and control of schistosomiasis, analyzes the challenges for the current schistosomiasis control programs and proposes the emphasis for future control activities in Dongting Lake areas, so as to provide insights into the schistosomiasis control program in this area.

Objective: To characterize a species of the genus Tricula and parasitized trematodes in schistosomiasis-endemic areas of Yunnan Province using a molecular analysis, so as to understand their taxonomic positions., Methods: Tricula spp. and Oncomelania snails were collected from Xiangyun County, Yunnan Province, and cercaria parasitizing snails were observed using crushing followed by microscopy. Cercaria parasitizing Tricula snails at various morphologies were sampled using a shedding method. Genomic DNA was extracted from snail soft tissues and cercariae, and the 16S rRNA , COI , 28S rDNA genes in snails and the ND1 and 28S rDNA genes in cercariae were amplified using a PCR assay and sequenced. The species of Tricula snails and their parasitized trematodes was characterized using sequence alignment and phylogenetic analysis., Results: Among 382 Tricula snails detected, there were three types of trematode cercariae found, including the non-forked (20.94%, 80/382), double-forked (3.40%, 13/382) and swallow shapes (7.07%, 27/382). Sequence and phylogenetic analyses showed that the 16S rRNA , COI and 28S rDNA gene sequences of this species of Tricula had high homology to those in Delavaya dianchiensis , and were clustered in a branch. Sequencing analysis of the ND1 and 28S rDNA genes revealed that the non-forked cercariae belonged to the family Pleu- rogenidae, the swallow-shaped cercariae belonged to the family Opecoelidae, and the double-forked cercariae belonged to another species of the genus Schistosoma that was different from S. sinensium and S. ovuncatum ., Conclusions: The species and taxonomy of Triculla spp. and their parasitized trematodes are preliminarily determined in schistosomiasis-endemic areas of Yunnan Province; however, further studies are required to investigate the more definite taxonomy and pathogenicity.

Oncomelania snail is the only intermediate host of Schistosoma japonicum , and controlling snail breeding and spread is an important intervention for schistosomiasis control. This review summarizes factors affecting snail spread, characteristics of snail spread in various endemic areas, high-risk environments of snail spread and monitoring methods of snail spread, so as to provide insights into the prevention of snail spread.

Schistosomiasis was once heavily endemic in Jiangsu Province. Following the control efforts for several decades, schistosomiasis was almost eradicated in all endemic counties in Jiangsu Province in 1980, and transmission control was achieved in the province in 2011. According to the principle of "implementing the control measures with adaptation to local circumstances and guiding the control programs with classified interventions", an integrated strategy with emphasis on the management of both infectious sources and snails has been recently employed for schitsosomiasis control in Jiangsu Province. In addition, a sensitive and highly effective surveillance system has been built and the application of novel techniques and information construction has been intensified to effectively interrupt the transmission of schistosomiasis in the Province. Transmission interruption of schistosomiasis was achieved in all endemic counties in Jiangsu Province. The paper summarizes the endemic situation of schistosomiasis, progress of schistosomiasis control, and major schistosomiasis control measures implemented during the stage of transmission interruption in Jiangsu Province.

This report presented the endemic status of schistosomiasis in the People's Republic of China at a national level in 2018, and analyzed the data collected from the national schistosomiasis prevention and control system and 453 national schistosomiasis surveillance sites. Among the 12 provinces (municipality and autonomous region) endemic for schistosomiasis in China, 5 provinces (municipality and autonomous region), including Shanghai, Zhejiang, Fujian, Guangdong and Guangxi, continued to consolidate the achievements of schistosomiasis elimination, Sichuan Province achieved transmission interruption and 6 provinces of Yunnan, Jiangsu, Hubei, Anhui, Jiangxi and Hunan achieved transmission control by the end of 2018. There were 450 endemic counties (cities, districts) covering 260 million people, specifically including 28 456 endemic villages covering 70.059 7 million people at risk of infection. Among the 450 endemic counties (cities, districts), 58.44% (263/450), 27.56% (124/450) and 14.00% (63/450) reached the criteria of elimination, transmission interruption and transmission control, respectively. By the end of 2018, a total of 29 214 advanced schistosomiasis cases were documented in China. In 2018, a total of 11.127 6 million individuals received inquiry examinations and 2.062 9 million were positive; 7.191 4 million individuals received serological tests and 138.5 thousand of them were positive, 532.2 thousand individuals received stool examinations and 8 were positive in China. In 2018, snail survey was performed in 19 821 endemic villages and Oncomehania snails were found in 7 321 villages, accounting for 36.94% of all surveyed villages, with 3 newly detected villages with snails in China. Snail survey covered an area of 590 241.01 hm 2 and 168 319.41 hm 2 snail habitats were found, including emerging snail habitats of 61.28 hm 2 ; however, no infected snails were identified. In 2018, a total of 646 823 bovines were raised in the schistosomiasis endemic areas of China, and 225 258 received serological examinations, with 2 638 positives detected, while 164 803 bovines received stool examinations, with 2 positives identified. In 2018, there were 90 388 patients with schistosomiasis receiving praziquantel chemotherapy, and expanded chemotherapy was given to 1 490 594 person-times; there were two bovines with schistosomiasis receiving praziquantel chemotherapy, and expanded chemotherapy was given to 352 577 bovine-times; chemical treatment was conducted in an area of 141 660.87 hm 2 , including an actual mollusciciding area of 75 308.26 hm 2 , and environmental improvements were performed in an area of 4 738.37 hm 2 in China. Data from the 453 national schistosomiasis surveillance sites of China showed that the mean Schistosoma japonicum infection rates were 0.001 5% and zero in humans and bovines in 2018, respectively, and no infected snails were found. The results demonstrate that the endemic situation of schistosomiasis appears a tendency towards a continuous decline in China; however, there is still a risk of schistosomiasis transmission, and challenges remain in achieving the target set in the Thirteenth Five-Year National Plan for Schistosomiasis Control in 2020 in some regions.

Objective: To analyze and investigate the changing trend of the endemic situation of schistosomiasis in national surveillance sites of Jiangsu Province from 2011 to 2018, so as to provide scientific evidence for formulating strategies for schistosomiasis control., Methods: From 2011 to 2014, the national schistosomiasis surveillance sites were set in seven schistosomiasis endemic counties (cities, districts) across Jiangsu Province as according to the National Schistosomiasis Surveillance Scheme (2011 version), and from 2015 to 2018, the national surveillance sites were assigned in all 64 counties (cities, districts) endemic for schistosomiasis in Jiangsu Province according to the National Schistosomiasis Surveillance Scheme (2014 version). Schistosoma japonicum infections in local populations, mobile populations and livestock, and snail status were monitored in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and the monitoring data were statistically analyzed., Results: The sero-prevalence of S. japonicum infections was 1.50% to 4.61% among local populations in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and a higher sero-prevalence was seen in men than in women, with the sero-positives predominantly detected in local populations at ages of over 50 years. The positive rate of stool examinations was 0 to 0.14% among sero-positive local populations in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and no acute case was found in local populations during the study period. The sero-prevalence of S. japonicum infections was 0.46% to 15.97% among mobile populations in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and no egg-positives were identified. A total of 1 453 livestock were tested in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and no S. japonicum infections were detected. During the period from 2011 through 2018, snail survey was conducted in an area of 216 million m 2 in the national schistosomiasis surveillance sites of Jiangsu Province, and 1 291.01 hm 2 snail habitats were identified, with snail densities ranging from 0.01 to 0.47 snails/0.1 m 2 ; however, no S. japonicum infections were identified in snails., Conclusions: The overall endemic situation of schistosomiasis appears a tendency towards a decline in Jiangsu Province, and S. japonicum infection remains at a low level in both humans and livestock. No S. japonicum infection has been identified in local populations in Jiangsu Province since 2012. In the future, monitoring and management of imported sources of S. japonicum infections should be intensified in Jiangsu Province, and the capability building of passive surveillance of schistosomiasis should be improved in sentinel hospitals in national schistosomiasis surveillance sites of Jiangsu Province. In addition, the examination of schistosomiasis should be strengthened in mobile populations in Jiangsu Province, a sensitive and effective surveillance-response system for schistosomiasis is urgently needed.

Acute schistosomiasis is a clinical type of schistosomiasis with severe symptoms. The number of acute schistosomiasis cases is not only a sensitive indicator to assess the endemic situation and control effects, but also an important indicator to define schistosomiasis outbreaks and evaluate the achievements of infection control or transmission control. Acute schistosomiasis control is therefore of great significance to achieve the goal of schistosomiasis elimination in China. This paper analyzes the features and causes of acute schistosomiasis, and proposes some suggestions for future acute schistosomiasis control in China.

Oncomelania hupensis , the only intermediate host of Schistosoma japonicum , is an indispensable part in the transmission of schistosomiasis, and snail control play a critical role in schistosomiasis prevention and control in China. This paper reviews the major molluscicides used currently and in the past and their application techniques in China. It is suggested that the research and development of molluscicides and their operational studies remain to be emphasized; notably, the novel molluscicides and new snail control techniques that meet the environmental protection requirements should be intensified. In addition, attentions should also be paid to the monitoring and evaluation of the field efficacy of molluscicides and snail control approaches, and it is necessary to evaluate the effect of molluscicides on environment and ecological security.

Objective: To analyze the endemic situation of schistosomiasis in Jiangshan City from 2008 to 2018, so as to provide evidence for formulating the future control strategy., Methods: The data regarding Oncomelania snail survey and control, schistosomiasis examinations and environmental improvements were collected in Jiangshan City from 2008 to 2018. The changes in snail status and morbidity due to Schistosoma japonicum infections were analyzed to assess the effectiveness of comprehensive schistosomiasis control., Results: From 2008 to 2018, a total of 61 220 person-times were examined for S. japonicum infections in Jiangshan City, and the overall seroprevalence of S. japonicum infections was 0.56% (343/61 220); however, no egg-positives were detected. Among 4 231 cattle screened for S. japonicum infections using blood tests in Jiangshan City during the period from 2008 to 2018, 12 were sero-positive, with sero-prevalence of 0.28% (12/4 231), and no egg-positives were identified. There were 422 snail habitats identified in Jiangshan City during the study period, covering an area of 46.915 hm 2 , and among the 31 686 snails dissected, no S. japonicum infections were detected. An area of 3 625.492 hm 2 snail habitats were subjected to repeated snail control and 11 settings were given environmental improvements, covering snail habitats of 17.880 hm 2 and historical snail habitats of 204.380 hm 2 ., Conclusions: Following the implementation of environmental improvements-based comprehensive schistosomiasis control, the endemic situation of schistosomiasis is stable in Jiangshan City; however, there is still a risk of snail importation and re-emerging schistosomiasis. Therefore, the monitoring of snails and morbidity due to S. japonicum infections should be intensified in the city.

Objective: To investigate the spatial distribution of Oncomelania hupensis snail habitats at the administrative village scale in schistosomiasis-endemic areas of Hubei Province, so as to provide scientific bases for precise control of O. hupensis snails in the province., Methods: Data regarding snail distribution at the village level in Hubei Province in 2017 were collected to create a spatial analysis database of snail distribution in Hubei Province. The spatial aggregations of O. hupensis distribution were analyzed using Moran's I index and Local Moran's I index. In addition, the distances from schistosomiasis-endemic villages to the Yangtze River were captured using the software ArcGIS 13.0, and their correlations with area of snail habitats were examined with the Spearman correlation method., Results: O. hupensis snails were mainly distributed in 5 450 endemic villages from 63 counties of 13 cities in Hubei Province in 2017. The global spatial autocorrelation analysis showed spatial aggregations in the areas of historically accumulated snail habitats, current areas of snail habitats, areas of snail habitats outside the embankment and snail habitats inside the embankment (all Z Scores > 0, all P values < 0.05), and no spatial aggregation was seen in the areas of snail habitats in hilly areas ( Z Score > 0, P > 0.05). There were four types of spatial distribution of historically accumulated areas of snail habitats, areas of current snail habitats, areas of snail habitats outside the embankment and snail habitats inside the embankment, including the high-high type (H-H type), high-low type (H-L type), low-high type (L-H type) and random distribution type, and a high percentage of the H-H type was found. There were 340, 125 and 110 endemic villages with the H-H type of areas of historically accumulated snail habitats, current areas of snail habitats and areas of snail habitats outside the embankment, and these villages were mainly concentrated in Wuhan and Jingzhou cities, with almost consistent spatial aggregation locations. There were 319 endemic villages with the H-H type of distribution of snail habitats inside the embankment, which were mainly distributed in Jingzhou, Xiaogan and Huangshi cities. In addition, the areas of historically accumulated snail habitats, current areas of snail habitats and areas of snail habitats outside the embankment negatively correlated with the distance from the endemic villages to the Yangtze River ( r = -0.094, P < 0.01; r = -0.225, P < 0.01; r = -0.177, P < 0.01)., Conclusions: The clustering areas of snail habitats along the Yangtze River Basin, notably the villages near the Yangtze River are key regions for snail monitoring and control in Hubei Province.

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., Conclusions: 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.

Objective: To analyze the surveillance data after schistosomiasis transmission interruption from 1985 to 2018, so as to provide scientific basis for the future prevention and control of schistosomiasis., Methods: The data pertaining to snail survey, surveillance of schistosomiasis in humans and livestock, and health education were collected and analyzed in Songjiang District after schistosomiasis transmission interruption from 1985 to 2018., Results: From 1985 to 2018, there were 8 townships, 68 villages and 1 462 settings with snails in Songjiang District, covering an area of 96.399 hm 2 . There were 4 townships and 59 villages with snails newly identified in previously schistosomiasis non-endemic areas, with emerging snail habitats of 60.161 hm 2 . A total of 26 148 snails were captured, and no infections were detected. The snail habitats were mainly distributed in the river course, ditches and farmlands, which accounted for 45.28%, 33.17% and 21.55% of total snail habitats, respectively. A total of 245 955 humans were subjected to the serological test, with a positive rate of 0.03%, and 37 humans were subjected to the parasitological test, with 3 positives detected. These three egg-positives were all imported chronic cases with schistosomiasis. A total of 9 109 livestock were detected using the serological test, and no infection was found. Most of the awareness rate of schistosomiasis control knowledge and the rate of correct behavior formation were over 80% in residents and students., Conclusions: The achievements of schistosomiasis control are consolidated in Songjiang District; however, there are still risk factors of schistosomiasis transmission, including residual snails, snail diffusion and importation of external source of infection. The future surveillance of schistosomiasis should focus on snails and sources of infection.

Objective: To understand the current distribution of Oncomelania snails in Sichuan Province, so as to provide scientific evidence for formulating the schistosomiasis elimination strategy and implementing the precision schistosomiasis control measures in the province., Methods: According to the National Scheme on Oncomelania hupensis Snails in China and the Scheme on Oncomelania hupensis Snails in Sichuan Province , snail surveys were performed in current snail habitats, historical snail habitats and suspected snail habitats using systematic sampling in Sichuan Province from 2016 to 2017, and the survey results were analyzed., Results: From 2016 to 2017, a total of 88 346 settings were surveyed in schistosomiasis-endemic areas of Sichuan Province, and 19 314 settings were detected with snails, covering an area of 4 829.25 hm 2 , with no Schistosoma japonicum infection identified in snails. A total of 3 017 915 frames were investigated in Sichuan Province, and 1 041 417 frames were found to have living snails, with totally 1 791 115 living snails captured. The mean density of living snails was 0.59 snails/0.1 m 2 , and the mean percentage of frames with living snails was 34.51% in Sichuan Province. The current snail habitats were mainly distributed in 1 704 villages, 377 townships, 54 counties (districts) of 9 cities (prefectures) across the schistosomiasis-endemic areas of Sichuan Province. Snail habitats were mainly found in ditches (70.22%), and weeds were the predominant vegetation in snail habitats (66.45%). Snails were firstly discovered in Sichuan Province in 1913, and S. japonicum -infected snails were firstly identified in 1956, with the latest identification of S. japonicum -infected snails in 2008., Conclusions: There are many settings suitable for snail breeding in Sichuan Province, and snail monitoring and control should be intensified in the future.

Objective: To investigate the epidemic factors of schistosomiasis in wetlands in Sichuan Province, so as to provide scientific evidence for the prevention and control of schistosomiasis in wetlands., Methods: The artificial and natural wetlands were selected from Sichuan Province, and the relevant data regarding wetlands were collected. Routine snail survey, investigation on human morbidity due to schistosomiasis, snail diffusion experiments, questionnaire survey, determination of water infectivity and retrospective survey were conducted., Results: In Sichuan Province, the mean densities of living snails were 0.003 snails/0.1 m 2 and 2.033 snails/0.1 m 2 in the upper and lower reaches of the Meiwan Reservoir wetlands, 0.08 snails/0.1 m 2 in the Jinyan Lake of Guanghan City, 0.21 snails/0.1 m 2 in Muhe River of Guanghan City, and 0.02 snails/0.1 m 2 prior to the construction of Qiong-hai wetland park in Xichang City in 2015. Artificial simulation experiments showed that the largest distance of snail diffusion in water was 2 000 m. There were 8.80% (41/466) of subjects that lived neighboring wetlands, worked in wetlands and visited wet-lands having infested water contact behaviors. A total of 690 sentinel mice were assigned, and no Schistosoma japonicum infection was detected in the 677 mice dissected. Retrospective survey showed that the construction of the Meiwan Reservoir caused the spread of schistosomiasis in Dailing County, and snails were found in the ditches entering the Jinyan Lake and in Jinyan Lake areas 5 years following the construction of the Jinyan Lake in Guanghan City, with S. japonicum -infected snails detected in the ditches entering the Jinyan Lake., Conclusions: O. hupensis snails are found in some wetlands in Sichuan Province. Protection of wetlands and snail control with environmental improvements are recommended for the prevention of snail importation in natural wetlands, while in artificial wetlands, thorough snail control is recommended during the construction of the wetlands because of the likelihood of snail importation via water systems. In addition, both natural and artificial wetlands require long-term systematic surveillance of schistosomiasis.

Objective: To understand the potential risk of schistosomiasis transmission in Xiuzhou District of Jiaxing City, so as to provide the scientific evidence for consolidating schistosomiasis control achievements., Methods: Fixed and mobile surveillance sites were set up in Xiuzhou District of Jiaxing City from 2013 to 2015. Oncomelania hupensis snails was surveyed historical snail habitats, current snail habitats, and suspected snail habitats. The schistosome infections were identified using serological and parasitological testing among local residents and mobile populations. In addition, the survival and reproduction of snails imported into Xiuzhou District was observed, and the schistosome infection in wild reservoir hosts was detected., Results: A total of 540.14 hm 2 of settings were surveyed in Xiuzhou District, Jiaxing City from 2013 to 2015, and 1.65 hm 2 of snail habitats were identified. The snail habitats were mainly located in dry lands, and no infected snails or importation of snails were found. During the period from 2013 to 2015, a total of 7 668 local residents and mobile populations were examined in Xiuzhou District, and no new local infections were detected; however, three imported schistosomiasis cases were identified. Field simulation experiment showed that the imported snails laid eggs and reproduced in Xiuzhou District, and no schistosome infections were found in wild animals., Conclusions: There are still residual Oncomelania snails and imported schistosomiasis patients in Xiuzhou District of Jiaxing City; therefore, the surveillance and management of local Oncomelania snails and imported schistosomiasis should be intensified to reduce the risk of schistosomiasis transmission.

Objective: To evaluate the effect of integrated schistosomiasis control measures in Honghu City during the period from 2008 through 2018., Methods: The data pertaining to schistosomiasis control measures and the endemic situation of schistosomiasis in Honghu City were collected from 2008 to 2018, and the effect of integrated schistosomiasis control measures implemented was evaluated., Results: The resources from agriculture, water resources, forestry, land, education and communication sectors were integrated to implement the integrated schistosomiasis control strategy with the focus on the control of source of Schistosoma japonicum infection in Honghu City from 2008 to 2018. The prevalence of S. japonicum infection reduced from 3.03% in 2008 to 0 in 2018 in humans in the city, and no acute infection was detected since 2009. In addition, the prevalence of S. japonicum infection in cattle reduced from 2.85% in 2008 to 0 in 2018, and no snail infection was found since 2012. Transmission control of schistosomiasis was achieved in the city in 2013, and transmission interruption was achieved in 2018., Conclusions: The integrated schistosomiasis control measures achieve remarkable effects in Honghu City; however, there is still a risk of schistosomiasis transmission.

Oncomelania hupensis is the only intermediate host of Schistosoma japonicum , and control of Oncomelania snails is an important measure to control and interrupt the transmission of schistosomiasis. Therefore, snail control plays a very critical role in the national schistosomiasis control programmes of China. Pyriclobenzuron, which was recently developed by National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, is the latest great advance in the research on molluscicides and is expected to solve the problem of toxicity to fish, which is worthy of expanding experiments.

Oncomelania hupensis is the only intermediate host of Schistosoma japonicum , and S. japonicum- infected Oncomelania snail is one of the major risk factor of schistosomiasis transmission. Therefore, the detection of S. japonicum -infected Oncomelania snails plays a vital role in the national schistosomiasis control programmes of China. Recently, a florescent recombinaseaided amplification (RAA) assay, developed by Jiangsu Institute of Parasitic Diseases, has shown rapid, sensitive and simple to detect S. japonicum- infected Oncomelania snails, which deserves expanded experiments.

Objective: To understand the endemic situation and control effect of schistosomiasis through the surveillance in a national surveillance site of Jurong City, so as to provide the evidence for formulating the prevention and control measures., Methods: According to the National Schistosomiasis Monitoring Scheme (2014 Edition) , the surveillance of schistosome infection in Oncomelania hupensis snails, residents and livestock was performed in the Kongqing Village, a national surveillance site of Jurong City, from 2015 to 2017., Results: The areas with snails were 0, 0, and 0.63 hm 2 in 2015, 2016, and 2017 respectively; the average densities of living snails were 0, 0, and 0.19 snails/0.1 m 2 in 2015, 2016, and 2017 respectively. No schistosome-infected snails were found. The positive rates of blood tests for schistosomiasis in the local residents were 7.72%, 7.45% and 3.45%, and the positive rates of blood tests in the floating population were 4.90%, 3.47% and 0.97% in 2015, 2016 and 2017, respectively. No positives were found in the schistosome etiology detection in the crowd and livestock., Conclusions: The effect of schistosomiasis prevention and control is obvious in Jurong City, but O. hupensis snails are still of recurrence. Therefore, the monitoring and control efforts should be strengthened to consolidate the achievements of schistosomiasis prevention and control.

Objective: To develop a florescent recombinase-aided amplification (RAA) assay for rapid detection of Schistosoma japonicum -infected Oncomelania snails and explore the optimal method for treatment of snail samples., Methods: Snail samples were divided into 3 groups, and each group consisted of 7 subgroups. There were 50 uninfected snails mixed with 1, 2, 3, 4, 5 and 10 infected snails in the 6 subgroups, respectively, and the remaining subgroup contained 100 uninfected snails mixed with 1 infected snails. DNA was extracted from snails in the three groups using a genomic DNA extraction kit following snail crushing and snail shells removal, crude nucleic acid extraction assay following snail crushing and snail shells removal, and crude nucleic acid extraction assay following direct snail crushing with snail shells preserved, and subjected to florescent RAA and PCR as says. The detection results were compared between the two assays., Results: A florescent RAA assay was developed, which completed the detection of S. japonicum -infected snails at 39 ℃ within 30 min. Following DNA extraction from mass snail samples with a genomic DNA extraction kit following snail crushing and snail shells removal, the lowest detection limit of the florescent RAA assay was one infected snail mixed in 100 uninfected snails, while the lowest detection limit of PCR assay was one infected snail mixed in 50 uninfected snails. Following DNA extraction using crude nucleic acid extraction method following snail crushing and snail shells removal, the lowest detection limit of the florescent RAA assay was one infected snail mixed in 100 uninfected snails, while the lowest detection limit of PCR assay was 3 infected snails mixed in 50 uninfected snails. Following DNA extraction with a crude nucleic acid extraction assay following direct snail crushing with snail shells preserved, the lowest detection limit of the florescent RAA assay was 10 infected snails mixed in 50 uninfected snails, while the lowest detection limit of PCR assay was 10 infected snails mixed in 50 uninfected snails., Conclusions: A fluorescent RAA assay that is rapid to detect S. japonicum -infected snails in mass snail samples is successfully developed, which is fast, sensitive and easy to perform. Crude nucleic acid extraction following snail crushing and snail shells removal is the optimal method for the treatment of snail samples.

Objective: To evaluate the actual effect of the schistosomiasis control program in Jiangsu Province from 2010 to 2015., Methods: A total of 67 schistosomiasis-endemic counties in 10 cities were selected, and a combination of retrospective investigation and on-site investigation was adopted to collect and record the epidemic data of the counties from 2010 to 2015, and a retrospective survey database of epidemic situation was established. The effects of integrated control strategies with both Oncomelania hupensis snail control and infection source control were evaluated., Results: From 2010 to 2015, 2 465 911 persons who lived in endemic areas were detected for schistosomiasis, with 16 974 positive cases of blood examinations, and 8 positive cases of fecal examinations. Totally 5 145 people with advanced schistosomiasis were treated and 40 460 people with the history of schistosome cercarial-infested water contact received the expanded chemotherapy. A total of 127 636 cattle raised in the endemic areas were detected, and 51 619 cattle (head-times) with the history of cercarial-infested water contact also received the expanded chemotherapy. The area with snails control by molluscicides was 18 604.84 hm 2 . By the end of 2015, schistosomeinfected snails had not been found and there was no zoological schistosome infection for 5 consecutive years, and in addition, there had been no acute schistosome-infected persons for 6 consecutive years in the whole province. The area with snails dropped to 1 977.18 hm 2 , with a decreasing rate of 55.24% compared with that in 2010., Conclusions: After the implementation of the plan for the prevention and control of schistosomiasis in Jiangsu Province (2010-2015), the prevention and control of schistosomiasis has achieved remarkable effects and realized the goal of the plan.

Objective: To construct a monitoring and risk assessment system of schistosomiasis epidemic focus in marshland, so as to grasp the risk of schistosomiasis transmission, and to provide the technical support for targeted prevention and control measures., Methods: The crowd and the risk source of schistosomiasis in Hankou marshland in Wuhan City were monitored to grasp the risk factors of schistosomiasis. The risk level was evaluated by the three-dimensional risk matrix and three-dimensional visualization method., Results: The total numbers of people on holidays and working days were 59 582 and 36 382 persontimes a day respectively in Hankou marshland. Fishing and swimming were the most common ways to contact the river water. The most majority of the people exposed to river water were male (73.9%), retirees (36.1%), local residents (69.7%) and people whose income was 1000 - 3000 yuan per month (52.1%), and the awareness of protection of them was low. In spring, the average density of living Oncomelania hupensis snails was 0.993/0.1 m 2 , the rat density was 7.72%, and the density of wild feces was 0.78/hm 2 . In autumn, the average density of living snails was 0.596 /0.1 m 2 , the rat density was 5.22%, and the density of wild feces was 0.32/hm 2 . The average density of living snails, the rat density and the density of wild feces were reduced by 39.9%, 32.4% and 59.0% respectively in autumn compared with those in spring. The risk assessment results of three-dimensional matrix showed that part 1 and part 2 were medium risk, part 3 was high risk and part 4 was maximum risk. The risk assessment results of the visualization method showed that the risk level increased from part 1 to part 4, which were basically consistent with the results of the risk matrix., Conclusions: There is a relatively large risk of schistosome infection in Hankou marshland in 2013. The surveillance and risk assessment system of epidemic focus is feasible and scientific.