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@#Abstract: Objective To evaluate the potential transmission risk of schistosomiasis in Yunnan Province, and to provide strategic basis for the prevention and control. Methods Based on the prevalence of schistosomiasis, the social and environmental factors that may lead to the epidemic, 1-3 villages from 3 provincial-level and 15 county-level counties (cities and districts) were selected as the evaluated villages in 2021. The risk of schistosomiasis spread was analyzed comprehensively by consulting, reviewing and collecting routine surveillance data of schistosomiasis in the villages, combined with snail and wild feces survey. The risk level was evaluated for the positive snails, positive wild feces, resident infection, average density of live snails and snail frame occurrence rate. Results Totally 7 snail counties schistosomiasis transmission was blocked of 18 epidemic counties and the rest were eliminated counties. A total of 152 447 snail frames were investigated and 3 043 frames with snails, 15 895 snails were captured and included 15 727 live snails in the 32 evaluated villages. The total area of snail was 58.87 hm2 and the area of reoccurrence was 34.19 hm2 with snail frame occurrence rate of 2.00% and average density of live snails 0.103 2/0.11 m2, and no positive snails were found by loop-mediated isothermal amplification (LAMP) assay. A total of 1 374 wild feces were collected in 27 evaluated villages of 14 epidemic counties, mainly from cattle, dogs, sheep, equine animals, pigs and so on, all of which were negative. According to the risk assessment of epidemic spread, Yongle Village and Yongsheng Village in Eryuan County, Zhiming Village in Chuxiong City were Ⅱ risk, and the rest were Ⅲ risk. Conclusions Although the risk of transmission is low in Yunnan Province, the risk of transmission and spread still exists. It is necessary to strengthen the risk monitoring, control of snail and effective management of livestock to prevent the rebound of the epidemic.
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Objective:To study the population distribution of Pomacea spp. in Shandong Province and the risk of angiostrongyliasis cantonensis in the local population, and to provide a basis for scientific prevention and control of related diseases. Methods:From July to December 2021, Yanzhou District of Jining City, Ningyang County of Taian City, and Dongying District of Dongying City were selected as surveillance sites to investigate the population and distribution range of Pomacea spp., live snail samples were collected for morphological and genetic identification, and Pomacea spp. infected with the larva of Angiostrongylus cantonensis was detected by lung test. At the same time, sentinel hospital case surveillance was carried out in Yanzhou District, Jining City, and questionnaire was used to study the local residents' awareness of angiostrongyliasis cantonensis and their personal health behaviors. Results:A total of 312 live snail samples were collected. After morphological identification, they were all Pomacea spp.. After gene sequencing, two populations of Pomacea canaliculata and Pomacea maculata were found. No positive snails infected with Angiostrongylus cantonensis were found. A total of 126 patients with headache as the main neurological symptom were admitted to the sentinel hospital, but there were no monitoring cases that met the inclusion criteria. Among the survey population, 48.38% (134/277) of the respondents had heard of angiostrongyliasis cantonensis, 44.77% (124/277) knew that eating Margarya melanioides might cause angiostrongyliasis cantonensis, and 83.39% (231/277) had no related unhealthy eating behavior. Conclusion:Pomacea spp. is found and reported for the first time in Shandong Province, and there is a risk of population infection with angiostrongyliasis cantonensis.
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Objective To assess the schistosomiasis transmission risk after flood disaster in Hubei Province in 2021, so as to provide a scientific basis for schistosomiasis prevention and control in corresponding areas. Methods The data pertaining to the endemic situation of schistosomiasis were collected from Hubei, including oncomelania snail distribution, and humans and livestock schistosomiasis infection. The warning water level and actual water situation were collected in corresponding water areas. The cumulative numbers of S. japonicum egg-positive people and cattle from 2014 to 2020, the distribution area of oncomelania snail in 2020, and the water levels from May 1 to August 31, 2021, were estimated and employed as parameters for classification of schistosomiasis transmission risk. The cumulative value of each risk index was calculated in each epidemic county (city and district) to comprehensively assess the risk of schistosomiasis transmission after flood disaster in each region. Results After the flood disaster in Hubei province in 2021, there were 2 counties (districts) at high risk of schistosomiasis transmission in Hubei based on the single risk index of fecal positive number. Based on comprehensive risk indices, there were 2 counties identified at grade 4 risk of schistosomiasis transmission. Conclusion After the flood in 2021, schistosomiasis in Hubei Province is mainly at low and medium epidemic risk. Xiantao City and Hanchuan City in Hanjiang River Basin are the two most seriously affected schistosomiasis epidemic cities. Flood disasters can increase the risk of schistosomiasis transmission and epidemic, so the monitoring and control of schistosomiasis after flood should be strengthened to control the disease transmission to the maximum extent.
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Schistosomiasis is an important zoonotic parasitic disease, and is categorized as a neglected tropical disease by the World Health Organization. Following the concerted efforts for more than 70 years, great achievements have been made in the national schistosomiasis control program in China, and the prevalence, disability and mortality due to schistosomiasis has remarkably dropped. Nevertheless, the frequent identification of imported schistosomiasis and the resulting potential transmission risk in mainland China have been recently paid much attention following the implementation of the “Belt and Road Initiative” and the China-Africa Cooperation Forum. This review describes the advances in the diagnostic tools for schistosomiasis, including pathogenic techniques, immunodiagnostic techniques and nucleic acid assays, in order to consolidate schistosomiasis control achievements and promote the capability for detection of external biological safety risks.
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With the deepening of the schistosomiasis research, risk assessment models have been widely used in schistosomiasis research and control. This paper reviews the theoretical basis and applications of common schistosomiasis risk assessment models and the Bayesian model, so as to provide insights into national schistosomiasis elimination program in China.
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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 hm2 snail habitats found, but no S. japonicum infections were detected in snails. In 2019, there was 6.17 hm2 snail habitats detected, with 2.17% (245/11 298) occurrence of frames with snails and a 0.06 snails/0.1 m2 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.
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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.
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Objective To evaluate the impact of the flood disaster on schistosomiasis transmission along the Yangtze River basin in 2020, so as to provide insights into schistosomiasis prevention and control in flood-affected areas. Methods The data pertaining to the endemic situation of schistosomiasis were collected from 5 provinces of Hunan, Hubei, Jiangxi, Anhui and Jiangsu from 2013 to 2019, including Schistosoma japonicum infections in humans and livestock and snail distribution, and the warning water levels and actual water status were collected in water regions locating in these 5 provinces. The cumulative numbers of S. japonicum egg-positive individuals and bovines during the period from 2013 to 2019, the area of snail habitats in 2019 and the water level on July 12, 2020 were estimated at a county level and employed as parameters for classification of schistosomiasis transmission risk. Then, the cumulative value of each risk index was calculated to assess the risk of schistosomiasis transmission risk. Results After the flood disaster along the Yangtze River basin in 2020, there were 10, 5 and 9 counties (districts) at high risk of schistosomiasis transmission in 5 provinces of Hunan, Hubei, Jiangxi, Anhui and Jiangsu based on number of egg-positive individuals, number of egg-positive bovines and snail distribution, respectively. Based on comprehensive risk indices, there were 10 (8 in Dongting Lake regions of Hunan Province and 2 in Poyang Lake regions of Jiangxi Province) and 15 counties (districts) (4 in Hubei Province, 7 in Hunan Province and 4 in Jiangxi Province) identified at grades 5 and 4 risk of schistosomiasis transmission. Conclusions Dongting Lake regions and Poyang Lake regions are the most severely flood-affected schistosomiasis-endemic foci of China in 2020, and the flood disaster may facilitate the transmission of schistosomiasis in affected areas. Therefore, schistosomiasis control requires to be intensified after the flood disaster to prevent the rebound of the disease.
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In 1980s, Biomphalaria straminea, an intermediate host of Schistosoma mansoni, was found in Shenzhen City, Guangdong Province, China, and currently, this snail has colonized in Shenzhen City and spread to peripheral cities involving of Dongguan and Huizhou. Since imported cases infected with S. mamoni have been reported from time to time in China, Mainland China is facing the potential risk of transmission of schistosomiasis mansoni. With the deepening of the opening-up policy, notably the implementation of the Belt and Road Initiative, there is an increase in the risk of transmission of schistosomiasis mansoni in Mainland China. Increasing the understanding on schistosomiasis mansoni, improving the awareness toward schistosomiasis mansoni prevention and control, and identifying, reporting and managing imported cases with S. mansoni infection or pathogen carriers, are of particular importance to prevent the development of entire life cycle of S. mansoni and the resultant schistosomiasis mansoni transmission in China. To protect public health, a consensus has been reached pertaining to the surveillance and control strategy of imported schistosomiasis mansoni by Chinese infectious disease experts and parasitologists, with aims to improve the awareness and capability for the diagnosis, treatment and control of imported schistosomiasis mansoni among Chinese disease control and prevention institutions and medical institutions, and decrease and even eliminate the risk of schistosomiasis mansoni transmission in China.
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Objective To understand the epidemic trend of schistosomiasis in China from 2010 to 2017 so as to provide the scientific evidence for schistosomiasis elimination. Methods The information of schistosomiasis control nationwide from 2010 to 2017 was collected, including the endemic of population, status of livestock control, and Oncomelania hupensis snail control. Microsoft Excel was applied for datum management and analysis. Results From 2010 to 2017, the epidemic of schistosomiasis in China dropped significantly. The decreasing amplitude of estimated number of patients nationwide was 88.46%. Seventy-one acute schistosomiasis patients were reported and 12.68% (9/71) of them were imported. The decreasing rate of cultivated cattle was 50.09%, and the accumulative number of schistosome-infected cattle was 17 239, and the average positive rate of stool examinations decreased from 1.04% to 0.000 22%. The area with snails nationwide was 373 596.18 to 363 068.95 hm2, and the new detected area with snails was 46.71 to 1 346.73 hm2. The area with schistosome-infected snails was 171.68 hm2 in 2012 and it was 9.25 hm2 in 2013. In 72 key monitoring points of 7 endemic provinces, there were 17 schistosome positive points of water body in 2010 and 6 points in 2016. There were some high risk-factors related to schistosomiasis transmission including schisto-some-infected cattle, dogs, and field rats, and the field stools, and the pasture in the area with snails in schistosomiasis monitoring points. Conclusions The endemic status of schistosomiasis in China has dropped significantly, and the transmission level is very low. However, the infectious source and risk factors in the endemic environments have not be eliminated. Therefore, the infectious source control, health education, snail control, and transmission monitoring should be strengthened, so as to promote the progress of schistosomiasis elimination.
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Objective To evaluate the potential risk of schistosomiasis transmission so as to provide the evidence for formulating the control strategy. Methods Two villages were selected as the investigated sites in Chuxiong City and the risk of schistosomiasis transmission was evaluated by reviewing the data of schistosomiasis epidemic situation and prevention and control work, and carrying out the field survey for Oncomelania hupensis snail status, wild faeces, and schistosome infection of the population from 2015 to 2017. Results There was 1.49 hm2 area of snail habitats, with an average density of 0.54 snails/0.1 m2. The occurrence rate of frames with snails was 5.41%. No schistosome-infected snails were found. The positive rate of schistosomiasis serological tests of the residents was 3.36%, but the stool examination positive cases were not found. A total of 58 wild faeces samples were collected but no schistosome infested cases were found. The risk levels of schistosomiasis transmission in both villages were Grade III. Conclusions Although Chuxiong City has been in a low risk state of schistosomiasis transmission, the density of snails is still high, and there is a risk of infection source importation. In the future, the infection source control and snail control should be strengthened.
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Earthquake is a serious natural disaster. The earthquake that occurs in schistosomiasis-endemic areas not only causes direct human and economic losses, but also induces secondary disasters that greatly threaten public health safety in affected areas. This paper analyzed the impact of the 2008 Wenchuan Earthquake and 2013 Lushan Earthquake on schistosomiasis transmission in Sichuan Province, and proposed emergency measures and assessment activitiesresponding to schistosomiasis following earthquake disasters. The experiences from schistosomiasis control after two earthquake disasters in Sichuan Province may provide insights into the emergency control in other regions or after other natural disasters.
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Objective To explore the spatial-temporal clustering distribution of schistosomiasis transmission risk in Yunnan Province from 2004 to 2015, so as to provide scientific evidence for the future schistosomiasis control and consolidation of the control achievements. Methods All data pertaining to endemic situation of human and bovine schistosomiasis and snail survey at a township level in Yunnan Province from 2004 to 2015 were collected. A descriptive epidemiological method and Joinpoint model were used to describe the changing trends of Schistosoma japonicum infections in humans, bovine and snails, and the hotspots and clusters of schistosomiasis transmission risk were identified using spatial autocorrelation analysis, hotspots analysis and retrospective space-time scan statistic in Yunnan Province from 2004 to 2015. Results The prevalence of S. japonicum infections appeared a continuous decline in humans, bovine and snails in Yunnan Province from 2004 to 2015, and the estimated number of schistosomiasis cases reduced from 43 056 in 2004 to 756 in 2015, with a decline rate of 98.24%. There were no acute cases since 2008 and no infected snails since 2014 in Yunnan Province. There were significant differences in the changing trends of human and bovine S. japonicum infections in Yunnan Province between 2012 and 2015 and between 2013 and 2015, respectively using the Joinpoint model (P < 0.05). In addition, there was a spatial autocorrelation in human S. japonicum infections in Yunnan Province from 2004 to 2013 (P < 0.01), and the hotspots areas for human S. japonicum infections were mainly distributed in some townships from Dali City, Weishan County and Eryuan County. Retrospective spatial-temporal scanning revealed that S. japonicum human, bovine and snail infections were clustered in 23, 15, 4 townships from Dali City, Weishan County, Eryuan County, Nanjian County and Heqing County, respectively, with relative risks of 6.25 to 28.75 (P < 0.01), which was almost consistent with the cluster areas detected by hotspots analysis. Conclusions The endemic situation of schistosomiasis significantly reduced in Yunnan Province from 2004 to 2015; however, there is still a risk of schistosomiasis transmission. The monitoring and control of schistosomiasis should be intensified in the future in Yunnan Province.
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Objective To build a schistosomiasis transmission risk surveillance system in Sichuan Province, so as to provide technical support for facilitating the progress towards schistosomiasis elimination in the province. Methods The surveillance sites for schistosomiasis transmission risk were assigned in 63 endemic counties (districts) of 11 cities (prefectures) in Sichuan Province. During the period from 2015 through 2018, wild feces contamination, the sources of Schistosoma japonicum infections (fever patients, livestock and wild animals), water infectivity in key settings, snail distribution in key settings, and snail breeding risk (snail importation and spread, floating debris carrying snails and snail breeding in ecological wetlands) were monitored in the surveillance sites. Results From 2015 to 2018, a total of 1 636 wild faces were detected in Sichuan Province, and 3 faces were positive for S. japonicum, with a 0.18% positive rate; among 3 995 livestock and 59 wild mice monitored, no S. japonicum infection was detected. A total of 49 414 fever patients were monitored in 2018, and 493 were seropositive for S. japonicum infection; then, 445 seropositives were subjected to stool examinations, and no egg-positives were found. From 2010 to 2018, a total of 93 sentinel sites were assigned, and 3 994 sentinel mice were placed for monitoring the water infectivity, with one S. japonicum-infected mouse detected. Between 2015 and 2018, a total of 4 156 key settings were investigated covering an area of 1 998.46 hm2, and 668 settings were detected with snails (16.07%), covering an area of 193.26 hm2; 497 suspected settings with a likelihood of snail importation with plant introduction were monitored from 2017 to 2018, and 65 settings with snails were found with 2 673 snails captured; 593 sites were assigned to collect the floating debris from 2017 to 2018, and 9 191.39 kg floating debris were collected with 186 snails captured; 4 wetlands were monitored for the risk of schistosomiasis transmission from 2013 to 2015, and snail breeding was found in 2 wetlands. No S. japonicum infection was identified in snails captured from all surveillance sites. Conclusions A sensitive and effective schistosomiasis transmission risk surveillance system has been successfully established in Sichuan Province. There is still a risk of schistosomiasis transmission risk in local areas of Sichuan Province. Therefore, the integrated schistosomiasis control measures with emphasis on the control of the source of S. japonicum infections should be further intensified, and snail monitoring and control and monitoring and control of schistosomiasis in wetlands should be also intensified.
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In 1980s, Biomphalaria straminea, an intermediate host of Schistosoma mansoni, was found in Shenzhen City, Guangdong Province, China, and currently, this snail has colonized in Shenzhen City and spread to peripheral cities involving of Dongguan and Huizhou. Since imported cases infected with S. mamoni have been reported from time to time in China, Mainland China is facing the potential risk of transmission of schistosomiasis mansoni. With the deepening of the opening-up policy, notably the implementation of the Belt and Road Initiative, there is an increase in the risk of transmission of schistosomiasis mansoni in Mainland China. Increasing the understanding on schistosomiasis mansoni, improving the awareness toward schistosomiasis mansoni prevention and control, and identifying, reporting and managing imported cases with S. mansoni infection or pathogen carriers, are of particular importance to prevent the development of entire life cycle of S. mansoni and the resultant schistosomiasis mansoni transmission in China. To protect public health, a consensus has been reached pertaining to the surveillance and control strategy of imported schistosomiasis mansoni by Chinese infectious disease experts and parasitologists, with aims to improve the awareness and capability for the diagnosis, treatment and control of imported schistosomiasis mansoni among Chinese disease control and prevention institutions and medical institutions, and decrease and even eliminate the risk of schistosomiasis mansoni transmission in China.
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Objective To understand the epidemic trend of schistosomiasis in China from 2010 to 2017 so as to provide the scientific evidence for schistosomiasis elimination. Methods The information of schistosomiasis control nationwide from 2010 to 2017 was collected, including the endemic of population, status of livestock control, and Oncomelania hupensis snail control. Microsoft Excel was applied for datum management and analysis. Results From 2010 to 2017, the epidemic of schistosomiasis in China dropped significantly. The decreasing amplitude of estimated number of patients nationwide was 88.46%. Seventy-one acute schistosomiasis patients were reported and 12.68% (9/71) of them were imported. The decreasing rate of cultivated cattle was 50.09%, and the accumulative number of schistosome-infected cattle was 17 239, and the average positive rate of stool examinations decreased from 1.04% to 0.000 22%. The area with snails nationwide was 373 596.18 to 363 068.95 hm2, and the new detected area with snails was 46.71 to 1 346.73 hm2. The area with schistosome-infected snails was 171.68 hm2 in 2012 and it was 9.25 hm2 in 2013. In 72 key monitoring points of 7 endemic provinces, there were 17 schistosome positive points of water body in 2010 and 6 points in 2016. There were some high risk-factors related to schistosomiasis transmission including schisto-some-infected cattle, dogs, and field rats, and the field stools, and the pasture in the area with snails in schistosomiasis monitoring points. Conclusions The endemic status of schistosomiasis in China has dropped significantly, and the transmission level is very low. However, the infectious source and risk factors in the endemic environments have not be eliminated. Therefore, the infectious source control, health education, snail control, and transmission monitoring should be strengthened, so as to promote the progress of schistosomiasis elimination.
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Objective To evaluate the potential risk of schistosomiasis transmission so as to provide the evidence for formulating the control strategy. Methods Two villages were selected as the investigated sites in Chuxiong City and the risk of schistosomiasis transmission was evaluated by reviewing the data of schistosomiasis epidemic situation and prevention and control work, and carrying out the field survey for Oncomelania hupensis snail status, wild faeces, and schistosome infection of the population from 2015 to 2017. Results There was 1.49 hm2 area of snail habitats, with an average density of 0.54 snails/0.1 m2. The occurrence rate of frames with snails was 5.41%. No schistosome-infected snails were found. The positive rate of schistosomiasis serological tests of the residents was 3.36%, but the stool examination positive cases were not found. A total of 58 wild faeces samples were collected but no schistosome infested cases were found. The risk levels of schistosomiasis transmission in both villages were Grade III. Conclusions Although Chuxiong City has been in a low risk state of schistosomiasis transmission, the density of snails is still high, and there is a risk of infection source importation. In the future, the infection source control and snail control should be strengthened.
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Earthquake is a serious natural disaster. The earthquake that occurs in schistosomiasis-endemic areas not only causes direct human and economic losses, but also induces secondary disasters that greatly threaten public health safety in affected areas. This paper analyzed the impact of the 2008 Wenchuan Earthquake and 2013 Lushan Earthquake on schistosomiasis transmission in Sichuan Province, and proposed emergency measures and assessment activitiesresponding to schistosomiasis following earthquake disasters. The experiences from schistosomiasis control after two earthquake disasters in Sichuan Province may provide insights into the emergency control in other regions or after other natural disasters.
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Objective To explore the spatial-temporal clustering distribution of schistosomiasis transmission risk in Yunnan Province from 2004 to 2015, so as to provide scientific evidence for the future schistosomiasis control and consolidation of the control achievements. Methods All data pertaining to endemic situation of human and bovine schistosomiasis and snail survey at a township level in Yunnan Province from 2004 to 2015 were collected. A descriptive epidemiological method and Joinpoint model were used to describe the changing trends of Schistosoma japonicum infections in humans, bovine and snails, and the hotspots and clusters of schistosomiasis transmission risk were identified using spatial autocorrelation analysis, hotspots analysis and retrospective space-time scan statistic in Yunnan Province from 2004 to 2015. Results The prevalence of S. japonicum infections appeared a continuous decline in humans, bovine and snails in Yunnan Province from 2004 to 2015, and the estimated number of schistosomiasis cases reduced from 43 056 in 2004 to 756 in 2015, with a decline rate of 98.24%. There were no acute cases since 2008 and no infected snails since 2014 in Yunnan Province. There were significant differences in the changing trends of human and bovine S. japonicum infections in Yunnan Province between 2012 and 2015 and between 2013 and 2015, respectively using the Joinpoint model (P < 0.05). In addition, there was a spatial autocorrelation in human S. japonicum infections in Yunnan Province from 2004 to 2013 (P < 0.01), and the hotspots areas for human S. japonicum infections were mainly distributed in some townships from Dali City, Weishan County and Eryuan County. Retrospective spatial-temporal scanning revealed that S. japonicum human, bovine and snail infections were clustered in 23, 15, 4 townships from Dali City, Weishan County, Eryuan County, Nanjian County and Heqing County, respectively, with relative risks of 6.25 to 28.75 (P < 0.01), which was almost consistent with the cluster areas detected by hotspots analysis. Conclusions The endemic situation of schistosomiasis significantly reduced in Yunnan Province from 2004 to 2015; however, there is still a risk of schistosomiasis transmission. The monitoring and control of schistosomiasis should be intensified in the future in Yunnan Province.
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Objective To build a schistosomiasis transmission risk surveillance system in Sichuan Province, so as to provide technical support for facilitating the progress towards schistosomiasis elimination in the province. Methods The surveillance sites for schistosomiasis transmission risk were assigned in 63 endemic counties (districts) of 11 cities (prefectures) in Sichuan Province. During the period from 2015 through 2018, wild feces contamination, the sources of Schistosoma japonicum infections (fever patients, livestock and wild animals), water infectivity in key settings, snail distribution in key settings, and snail breeding risk (snail importation and spread, floating debris carrying snails and snail breeding in ecological wetlands) were monitored in the surveillance sites. Results From 2015 to 2018, a total of 1 636 wild faces were detected in Sichuan Province, and 3 faces were positive for S. japonicum, with a 0.18% positive rate; among 3 995 livestock and 59 wild mice monitored, no S. japonicum infection was detected. A total of 49 414 fever patients were monitored in 2018, and 493 were seropositive for S. japonicum infection; then, 445 seropositives were subjected to stool examinations, and no egg-positives were found. From 2010 to 2018, a total of 93 sentinel sites were assigned, and 3 994 sentinel mice were placed for monitoring the water infectivity, with one S. japonicum-infected mouse detected. Between 2015 and 2018, a total of 4 156 key settings were investigated covering an area of 1 998.46 hm2, and 668 settings were detected with snails (16.07%), covering an area of 193.26 hm2; 497 suspected settings with a likelihood of snail importation with plant introduction were monitored from 2017 to 2018, and 65 settings with snails were found with 2 673 snails captured; 593 sites were assigned to collect the floating debris from 2017 to 2018, and 9 191.39 kg floating debris were collected with 186 snails captured; 4 wetlands were monitored for the risk of schistosomiasis transmission from 2013 to 2015, and snail breeding was found in 2 wetlands. No S. japonicum infection was identified in snails captured from all surveillance sites. Conclusions A sensitive and effective schistosomiasis transmission risk surveillance system has been successfully established in Sichuan Province. There is still a risk of schistosomiasis transmission risk in local areas of Sichuan Province. Therefore, the integrated schistosomiasis control measures with emphasis on the control of the source of S. japonicum infections should be further intensified, and snail monitoring and control and monitoring and control of schistosomiasis in wetlands should be also intensified.