A multidisciplinary, integrated approach for the elimination of schistosomiasis: a longitudinal study in a historically hyper-endemic region in the lower reaches of the Yangtze River, China from 2005 to 2014.

BACKGROUND: Although great success has been achieved, schistosomiasis remains a major public health concern in China, and the remaining core endemic regions are concentrated along the middle and lower reaches of the Yangtze River. In this longitudinal study, we evaluated the effectiveness of a multidisciplinary, integrated approach for schistosomiasis elimination in a historically hyper-endemic region in the lower reaches of the Yangtze River, China over the 10-year period from 2005 through 2014. METHODS: A three-step roadmap for schistosomiasis elimination was designed in the study site, and multidisciplinary, integrated interventions were implemented by the health, agriculture, water resources development, land and resources, and forestry sectors from 2005 to 2014, including chemotherapy for infected individuals, health education, management of the source of Schistosoma japonicum infection, and intermediate host snail control. The annual number of schistosomiasis patients, S. japonicum infection in humans, bovines and Oncomelania hupensis snails, and water infectivity were observed to assess the effectiveness of the multidisciplinary, integrated approach for the elimination of schistosomiasis. RESULTS: There was a tendency towards a gradual decline in both the number of schistosomiasis cases and the prevalence of S. japonicum human infection across the study period from 2005 through 2014. No S. japonicum human infection was detected since 2012, and no acute infection was seen since 2006. During the study period, no infection was found in bovines, and a 0.03% overall infection rate was observed in O. hupensis snails. Since 2009, no infected snails were identified, and the area of both snail habitats and infected snail habitats appeared a reduction over the study period. Following the 3-year multidisciplinary, integrated control, infection control was achieved, and transmission control was achieved after 6-year implementation, with all infected snails and water infectivity eliminated; in addition, the 10-year implementation resulted in interruption of schistosomiasis transmission in the study site in 2014. CONCLUSIONS: The results of the present 10-year longitudinal study demonstrate that the multidisciplinary, integrated approach is effective for the elimination of schistosomiasis as a public health problem in the lower reaches of the Yangtze River, China.

Approaches being used in the national schistosomiasis elimination programme in China: a review.

Schistosomiasis japonica, caused by the human blood fluke Schistosoma japonicum, remains a major public health problem in China, although great success has been achieved. The control efforts during the past half-decade, notably the wide implementation of the new integrated strategy with emphasis on control of the source of S. japonicum infection across the country since 2004, has greatly reduced S. japonicum in humans, livestock, and intermediate host Oncomelania hupensis snails, and transmission control of schistosomiasis was achieved in China in 2015. A two-stage roadmap was therefore proposed for schistosomiasis elimination in 2015, with aims to achieve transmission interruption by 2020 and achieve disease elimination by 2025 in the country. During the last two decades, a variety of approaches, which target the epidemiological factors of schistosomiasis japonica have been developed, in order to block the transmission cycle of the parasite. These approaches have been employed in the national or local schistosomiasis control activities, and facilitated, at least in part, the progress of the schistosomiasis elimination programs. Here, we present an approach to control the source of S. japonicum infection, three new tools for snail control, three approaches for detecting and monitoring S. japonicum infection, and a novel model for health education. These approaches are considered to play a great role in the stage moving towards transmission interruption and elimination of schistosomiasis in China.

An integrated environmental improvement of marshlands: impact on control and elimination of schistosomiasis in marshland regions along the Yangtze River, China.

BACKGROUND: Schistosomiasis is a global snail-transmitted infectious disease of poverty. Transmission control had been achieved in China in 2015 after the control efforts for over 60 years. Currently, the remaining core regions endemic for Schistosoma japonicum are mainly located in the marshland and lake regions along the Yangtze River basin. METHODS: During the period from 2001 through 2015, an integrated environmental improvement of the marshlands was carried out through the implementation of industrial, agricultural and resources development projects in Yizheng County along the Yangtze River. S. japonicum infection in humans, livestock and snails was estimated by serology, stool examination, hatching technique and microscopy during the 15-year study period to evaluate the effect of the integrated environmental improvement on control and elimination of schistosomiasis. RESULTS: A 0.05% overall rate of S. japonicum infection was observed in snails during the 15-year study period, and no infected snails were detected since 2012. The overall prevalence of S. japonicum infection was 0.09% in humans during the study period, and no human infection was found since 2012. In addition, only 13 bovines were identified with S. japonicum infection in 2003 during the 15-year study period, and since 2004, no infection was found in livestock. CONCLUSION: The results of the present study demonstrate that the implementation of industrial, agricultural and water resources development projects, not only alters snail habitats in marshland regions, and promotes local economic development, which appears a win-to-win strategy to block the transmission of S. japonicum and accelerate socio-economic development along the Yangtze River.

[Integration and demonstration of key techniques in surveillance and forecast of schistosomiasis in Jiangsu Province III Development of a machine simultaneously integrating mechanized environmental cleaning and automatic mollusciciding].

OBJECTIVE: To develop a machine simultaneously integrating mechanized environmental cleaning and automatic mollusciciding and to evaluate its effectiveness of field application, so as to provide a novel Oncomelania hupensis snail control technique in the large-scale marshlands. METHODS: The machine simultaneously integrating mechanized environmental cleaning and automatic mollusciciding, which was suitable for use in complex marshland areas, was developed according to the mechanization and automation principles, and was used for O. hupensis snail control in the marshland. The effect of the machine on environmental cleaning and plough was evaluated, and the distribution of living snails was observed at various soil layers following plough. The snail control effects of plough alone and plough followed by mollusciciding were compared. RESULTS: The machine could simultaneously complete the procedures of getting vegetation down and cut vegetation into pieces, plough and snail control by spraying niclosamide. After plough, the constituent ratios of living snails were 36.31%, 25.60%, 22.62% and 15.48% in the soil layers at depths of 0-5, 6-10, 11-15 cm and 16-20 cm respectively, and 61.91% living snails were found in the 0-10 cm soil layers. Seven and fifteen days after the experiment, the mortality rates of snails were 9.38% and 8.29% in the plough alone group, and 63.04% and 80.70% in the plough + mollusciciding group respectively (χ²7 d = 42.74, χ²15 d = 155.56, both P values < 0.01). Thirty days after the experiment, the densities of snails were 3.02 snails/0.1 m² and 0.53 snails/ 0.1 m² in the soil surface of the plough alone group and the plough + mollusciciding group, which decreased by 64.92% and 93.60%, respectively, and the decrease rate of snail density was approximately 30% higher in the plough + mollusciciding group than that in the plough alone group. CONCLUSIONS: The machine simultaneously integrating mechanized environmental cleaning and automatic mollusciciding achieves the integration of mechanical environmental cleaning and automatic niclosamide spraying in the complex marshland areas, which provides a novel technique of field snail control in the large-scale setting in China.

[Integration and demonstration of key techniques in surveillance and forecast of schistosomiasis in Jiangsu Province I Layout and effect of the demonstration sites for schistosomiasis surveillance and forecast].

OBJECTIVE: To explore and integrate the key techniques used in the surveillance and forecast of schistosomiasis in the water regions along the Yangtze River, so as to provide technical support for identifying rapidly the risk of schistosomiasis transmission and implementing control measures targeting the risk. METHODS: According to the distribution of water systems and water regions along the Yangtze River in Jiangsu Province, the demonstration sites for surveillance and forecast of schistosomiasis were set across the province, where the integration and demonstration of the techniques regarding monitoring of Schistosoma japonicum infection in sentinel mice, human and animal activities, release of forecast information, and emergency treatment of water regions at risk of infection were performed. The pattern of human and animal activities was compared with the S. japonicum infection in sentinel mice in the demonstration sites, and the operability of the release of information and emergency treatment of the risk of S. japonicum infection was evaluated. RESULTS: A total of 50 demonstration sites for surveillance and forecast of schistosomiasis were set in fixed anchor points, opening of the navigation lock to the Yangtze River, freight terminal, agritainment places, ferry, large construction places, and places for guaranteeing the Youth Olympic Games in 23 counties (districts) of 5 cities, Jiangsu Province. During the period between May. and September, 2014, the infectivity of water body was monitored by using 5 batches of sentinel mice, with a 99.06% (4,954/5,001) gross recovery rate of mice. S. japonicum infection was detected in a demonstration site, and an infected mouse was found, with a 0.02% (1/4,933) gross positive rate of sentinel mice. The field survey showed 2 088 person-times contacting water, including 91.95% (1,920/2,088) contacting water due to the production such as capturing fish, harvesting and cultivating crops, and repairing and building boats, and 8.05% (168/2 088) contacting water due to the life activity, such as fishing, washing vegetables and playing with water. The people contacted water predominantly in August and September (49.57%). A total of 859 boats containing 1,877 boatmen were observed, 68.22% (586/859) of which were fishing boats containing 1,306 fishermen (69.58%). There were 32 sheep found in 4 demonstration sites, and 3 sheep were seen in the demonstration site with infected sentinel mouse. Four blue forecasts (emergence of water contact) and one orange forecast (S. japonicum-infected sentinel mouse detected) were released across the province, with one forecast map released which showed 5 sites with fishing and one site with sheep grazing, one emergency response system initiated, mollusciciding implemented in 10 hm2 high-risk regions, 120 sheep grazed in fence, and 35 fishermen given health-education materials, schistosomiasis examination and preventive therapy. In addition, no acute schistosomiasis occurred in the demonstration site with S. japonicum-infected sentinel mice. CONCLUSIONS: The integration and demonstration of the techniques regarding monitoring of S. japonicum infection in sentinel mice, human and animal activities, release of forecast information, and emergency treatment of water regions at risk of infection provides an effective approach for the large-scale surveillance and forecast of schistosomiasis.

[Appropriate technology: a driver to eliminate schistosomiasis in China. In- sights gained from the First Forum on Schistosomiasis Control in China].

This paper described the First Forum on Schistosomiasis Control in China. With "Appropriate technology is essential to schistosomiasis prevention and control" as the topic, the forum shared the main interventions and experiences for schistosomiasis control and elimination, exhibited the recent achievements gained from the development of appropriate technology for schistosomiasis control, showed the technical support of appropriate technology for schistosomiasis elimination, and proposed the priority for the future research and development of appropriate technology for schistosomiasis control and elimination in China. It is considered that the forum builds a bridge for communicating information between the administrative sectors and specialized prevention and control institutions, between research institutions and manufactures, and between experts/professors and grassroots professional staff, and provides a platform to communicate the national schistosomiasis control knowledge of China.

[Integration and demonstration of key techniques in the surveillance and forecast of schistosomiasis in Jiangsu Province II Molluscicidal effect of 5% niclosamide ethanolamine granules in large-scale settings].

OBJECTIVE: To evaluate the field molluscicidal effect of 5% niclosamide ethanolamine granules, so as to provide a novel Oncomelania hupensis snail control approach for emergency treatment of high-risk settings. METHODS: Snail control tests with spraying of 5% niclosamide ethanolamine granules were conducted in two settings of 2 counties, and the dose-, time- and setting-specific field molluscicidal effects were tested. RESULTS: In the small-scale setting, spraying of 5% niclosamide ethanolamine granules at doses of 30, 40 and 50 g/m2 resulted in 54.55%, 68.41% and 73.45% 1-day snail mortality, 57.27%, 68.59% and 80.28% 3-day snail mortality, and 63.49%, 77.58% and 85.55% 7-day snail mortality, respectively, and no significant differences were detected in 1- and 3-day snail mortality caused by spraying of 5% niclosamide ethanolamine granules at doses of 30 and 40 g/m2 (all P > 0.05), while significant difference was found in the 7-day snail mortality (χ2 = 4.549, P < 0.05). In addition, spraying of 5% niclosamide ethanolamine granules at doses of 40 and 50 g/m2 resulted in comparable 1-, 3- and 7-day snail mortality (all P > 0.05). In the large-scale setting, spraying of 5% niclosamide ethanolamine granules at a dose of 40 g/m2 resulted in 85.29% and 87.70% 3-day snail mortality, 83.89% and 91.02% 7-day snail mortality, and 83.41% and 91.84% 15-day snail mortality in the environment-cleaning group and non-cleaning group, respectively. The overall snail mortality was 90.02% in the environment-cleaning group 3 to 15 days after spraying, which was significantly higher than that (84.28%) in the non-cleaning group (χ2 = 9.950, P < 0.05). After 15 days of spraying with 5% niclosamide ethanolamine granules at a dose of 40 g/m2, the densities of living snails reduced from 19.90 and 19.83 snails/0.1 m2 to 0.60 and 2.60 snails/0.1 m2 in the environment-cleaning group and non-cleaning group, with 96.98% and 86.89% reductions, respectively. CONCLUSION: The appropriate dose of 5% niclosamide ethanolamine granules is 40 g/m2 for snail control in the field, and environment cleaning of vegetation with a height of more than 50 cm may improve the molluscicidal efficacy.

[Discovery and biology of Schistosoma haematobium].

Schistosomiasis is a neglected tropical disease that severely threatens human health and affects the socioeconomic development. The causative agent that parasitizes in humans mainly involves Schistosoma japonicum, S. mansoni, S. haematobiurn, S. intercalatum and S. mekongi. As the firstly identified schistosome, S. haematobium infection is found to strongly correlate with bladder cancer. This paper mainly reviews the discovery, morphology and life cycle of S. haematobium.

[Bibliometric analysis of literature regarding integrated schistosomiasis control strategy with emphasis on infectious source control].

OBJECTIVE: To evaluate the outcomes of implementation of integrated schistosomiasis control strategy with emphasis on infectious source control using a bibliometric method. METHODS: The literature pertaining to integrated schistosomiasis control strategy with emphasis on infectious source control was retrieved from CNKI, Wanfangdata, VIP, PubMed, Web of Science, BIOSIS and Google Scholar, and a bibliometric analysis of literature captured was performed. RESULTS: During the period from January 1, 2004 through September 30, 2014, a total of 94 publications regarding integrated schistosomiasis control strategy with emphasis on infectious source control were captured, including 78 Chinese articles (82.98%) and 16 English papers (17.02%). The Chinese literature was published in 21 national journals, and Chinese Journal of Schistosomiasis Control had the largest number of publications, consisting of 37.23% of total publications; 16 English papers were published in 12 international journals, and PLoS Neglected Tropical Diseases had the largest number of publications (3 publications). There were 37 affiliations publishing these 94 articles, and National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (16 publications), Anhui Institute of Schistosomiasis Control (12 publications) and Hunan Institute of Schistosomiasis Control (9 publications) ranked top three affiliations in number of publications. A total of 157 persons were co-authored in these 94 publications, and Wang, Zhou and Zhang ranked top 3 authors in number of publications. CONCLUSION: The integrated schistosomiasis control strategy with emphasis on infectious source control has been widely implemented in China, and the achievements obtained from the implementation of this strategy should be summarized and transmitted internationally.

[Surveillance and risk assessment system of schistosomiasis in Jiangsu Province. I. Distribution of surveillance site and effectiveness of the system].

OBJECTIVE: To establish the surveillance and risk assessment system of schistosomiasis in Jiangsu Province, so as to provide technical support for timely understanding of the risk of schistosomiasis transmission and implementation of targeted control measures. METHODS: The surveillance sites of schistosomiasis were assigned according to the epidemic status and endemic type of schistosomiasis as well as the characteristics of the water system, and the prevalence of Schistosoma japonicum in humans and domestic animals, and snail status were investigated. In addition, the quality control of serum detection of S. japonicum infections was performed. The prevalence of human and animal S. japonicum infections, snail status and missing diagnosis of serum detection were analyzed and compared among regions. RESULTS: A total of 27 surveillance sites of schistosomiasis were set up in 26 counties of 10 cities, Jiangsu Province, including 14 sites in transmission-interrupted villages and 13 sites in transmission-controlled villages, and 15 sites in marshland and lake regions, 9 sites in plain regions with water network and 3 sites in mountainous region. In the 27 surveillance sites, a total of 16 617 residents were screened for S. japonicum infection by using dipstick dye immunoassay (DDIA), and 326 were sero-positive, with a sero-prevalence of 1.96% (2.17% for men and 1.8% for women). Of the 326 individuals undergoing parasitological examination, 2 positive cases were detected in the marshland and lake region, with a S. japonicum human prevalence of 0.01%. Of the 762 floating population detected, 10 were positive for blood test, with a sero-prevalence of 1.31%, and no egg-positive individuals were detected. No infection was found in the 476 domestic animals. Of the 746 settings surveyed, a total of 240.7 hm2 snail area was detected, with a mean snail density of 0.06 snails/0.1 m2, and no infected snails were found. There were 780 quality-control sera detected in 26 surveillance sites of schistosomiasis, and the gross coincidence rate was 95.13%, with misdiagnosis rate of 1.28% and missing diagnosis rate of 19.23%. CONCLUSION: The surveillance sites of schistosomiasis show reasonable distribution in Jiangsu Province, and the endemic situation of schistosomiasis appears a low level in the whole province.

[Risk assessment and control measures for import of African schistosomiasis into China].

The habitats of Biomphalaria straminea, the intermediate host of Schistosoma mansoni, have been found in Hong Kong Special Administrative Region and Shenzhen City of People's Republic of China. Currently, there is a sharp increase in the number of Africa-aid projects and workers moving to Africa, and more and more cases infected with S. mansoni or S. haematobium returning from African countries have been detected in China. The possibility of transmission of African schistosomiasis in Chinese mainland, in the context of global climate warming, has received much attention. This paper illustrates the risk of transmission of African schistosomiasis in China based on biological and epidemiological features, and proposes interventions to tackle the risk.

African schistosomiasis in mainland China: risk of transmission and countermeasures to tackle the risk.

Schistosomiasis is a major disease of public health importance in humans occurring in 76 countries of the tropics and sub-tropics. In China, schistosomiasis japonica is one of the highest priorities in communicable disease control defined by the central government. Since 1970s, the habitats of Biomphalaria straminea, an intermediate host of Schistosoma mansoni in South America, have been identified in Hong Kong Special Administrative Region and Shenzhen city, Guangdong province of China. With the sharp growth in the China-aided projects in Africa and labor services export to Africa, a gradual rise in the cases infected with S. haematobium or S. mansoni is reported in those returning from Africa to China. The existence of intermediate snail hosts and import of infectious source of schistosomiasis results in concern about the transmission of African schistosomiasis in mainland China in the context of global climate change. This paper evaluates the risk of transmission of African schistosomiasis in China, and proposes countermeasures and research priorities to tackle the risk.

[Field evaluation of a novel plant molluscicide "Luo-Wei" against Oncomelania hupensis I molluscicidal effect by the spraying method in lake and marshland regions].

OBJECTIVE: To evaluate the field effect of a novel plant molluscicide "Luo-wei" (Tea-seed distilled saponins, TDS) against Oncomelania hupensis in the lake and marshland regions. METHODS: A spraying experiment was carried out in the grassland of two schistosomiasis endemic counties, including Xingzi in Jiangxi Province and the Huarong in Hunan Province, to assess the molluscicidal effect of 4% TDS comparing with 50% wettable powder of niclosamide ethanolamine salt (WPN). The chi2 test was used to examine the differences between regions, molluscicides, or days after spraying. RESULTS: Following 1, 3, 7, and 15 days of test, the snail mortality showed a simultaneous increase both in TDS group (70.43%-86.88%) and WPN group (70.21%-85.35%). There is no significant difference between TDS and WPN of day 1, 7 and 15 (all P values > 0.05), but except for day 3 (chi2 = 3.910, P = 0.048). By the end of day 15, the snail mortality for TDS was 86.53% in Xingzi and 88.28% in Huarong, while for WPN was 83.04% in Xingzi and 93.69% in Huarong respectively; the decline rate of snail density for TDS was 85.29% in Xingzi and 93.53% in Huarong, while for WPN was 85.29% in Xingzi and 93.53% in Huarong respectively. The adjusted mortality of different days ranged from 69.63% to 86.54% in the the TDS group, and 69.41% to 86.54% in the WPN group. CONCLUSION: The molluscicidal effect of TDS by spraying is similar to that of WPN. It is time to popularize this new plant molluscicide (TDS) in a wider field.

[Establishment and application of quality control system for detection of schistosomiasis in Jiangsu Province I ability of serological detection among county-level personnel].

OBJECTIVE: To evaluate the ability for serological screening of schistosomiasis among county-level personnel, so as to provide the evidence for establishing the quality control system of field detection of schistosomiasis. METHODS: The standard serum panel was prepared for the quality assessment of schistosomiasis diagnostic capability, and detected by county-level personnel in the endemic field simultaneously using single-blind method. The rates of coincidence, misdiagnosis and missed diagnosis were calculated compared with the standard results. RESULTS: Totally 780 samples of standard serum were detected in 26 counties, and showed 134 positive and 646 negative samples. The rates of coincidence, misdiagnosis and missed diagnosis were 95.13%, 1.28% and 19.23%, respectively, and there was a significant difference between the detection results and the standard results (chi2 = 11.6053, P = 0.0007). Among the 26 counties investigated, the misdiagnosis occurred in 5 counties (19.23%) and missed diagnosis occurred in 21 counties (80.77%). The misdiagnosis rate and missed diagnosis rate of serological screening of schistosomiasis were 0-2.08% and 16.67%-33.33% in beach, hilly, water net and marshland endemic areas, respectively, and no significant differences were found in the misdiagnosis rate and the missed diagnosis rate among various types of endemic areas (chi2 = 1.590 and 1.757, P = 0.6671 and 0.6244). The rates of misdiagnosis and the missed diagnosis were 1.14% and 1.39%, and 18.18% and 20.00% in the schistosomiasis transmission-controlled and the schistosomiasis transmission-interrupted areas, respectively, and no significant differences were found in the misdiagnosis rate and missed diagnosis rate between the schistosomiasis transmission-controlled and transmission-interrupted areas (chi2 = 0.008 and 0.001, P = 0.931 and 0.974). CONCLUSIONS: The missed diagnosis is a major cause for the reduction of quality of schistosomiasis detection at the county level in Jiangsu Province, and the coincidental detection of schistosomiasis with standard serum in the field is one of effective approaches for the control of the quality of schistosomiasis detection.

[Field evaluation of a novel plant molluscicide "Luo-wei" against the snail Oncomelania hupensis III molluscicidal effect by spraying method in hilly regions].

OBJECTIVE: To evaluate the molluscicidal effect of a novel plant molluscicide "Luo-wei" (Tea-seed distilled saponins, TDS) against Oncomelania httpensis in billy regions. METHODS: The molluscicidal effect of TDS at a dose of 5 g/m2 by the spraying method against Oncomelania snails was assessed in a setting with a high snail density in Husban Village, Jiangning District of Nanjing City, and the effect was compared with that of 50% wettable powder of niclosamide ethanolamine salt (WPN) at a dose of 2 gIm2 at different time after spraying. RESULTS: Afterl, 3, 7 and 15 day (days) of the spraying experiment, the snail death rates of the TDS group were 56.47%, 57.32%, 90.58% and 93.41% respectively, while those of the WPN group were 49.22%, 53.37%, 95.92% and 97.26%, respectively. The differences between the rates of the 2 groups 1, 7, 15 day (days) after the spraying were statistically significant (all P < 0.05). Fifteen days after the spraying, the density of living snails reduced from 20.30 +/- 16.20 snails/0.1 m2 and 23.67 +/- 21.22 snails/0.1 m2 to 2.28 +/- 2.17 snails/0.1 m2 and 1.27 +/- 0.76 snailsl0.1 m2 in the TDS group and WPN group, respectively, with the reduction rates of 88.77% and 94.63%, respectively. CONCLUSION: TDS can be used as an alternative molluscicide for the control of Oncornelania snails in hilly areas, which deserves further popularization.

[Comparison of molluscicidal effects of two snail control methods with plastic film covering in hilly regions].

OBJECTIVE: To evaluate and compare the molluscicidal effects of colorless and black plastic film covering methods against Oncomelania hupensis snails in hilly regions. METHODS: A hilly setting with high snail density was selected as the study area, and three groups including the colorless plastic film covering method, black plastic film covering method and control were designed. The snail surveys were conducted 1, 3, 7, 15 days and 30 days in each group following plastic film covering, and the mortality of snails and reduction of snail density were investigated. The air temperature, soil surface temperature in the control group, as well as the soil surface temperature and the temperatures 5 cm and 15 cm under the soil within the film were recorded. RESULTS: The mortality rates of snails were 36.84%, 78.94%, 95.92%, 100.00% and 99.45% 1, 3, 7, 15 days and 30 days following colorless plastic film covering, respectively, and the snail density after 30 days of covering reduced by 99.36% as compared to that before covering, while the mortality rates of snails were 10.08%, 8.94%, 6.11%, 26.15% and 49.32% 1, 3, 7, 15 days and 30 days following black plastic film covering, respectively, and the snail density after 30 days of covering reduced by 58.10% as compared to that before covering. There were significant differences in the 1-, 3-, 7-, 15-day and 30-day snail mortality rates between the colorless and black film covering groups (all P values <0.01), and a significant difference was detected in the snail density between the two groups 30 days after the film covering (P < 0.001). In addition, the speed, amplitude and duration of the rise in the soil surface temperature within the colorless film were all greater than those within the black film. CONCLUSION: The short-term molluscicidal effect of the colorless plastic film covering method is significantly superior to that of the black plastic film covering method in summer in hilly regions.

[Engineering management mode of mollusciciding and assessment of its field application].

OBJECTIVE: To establish the engineering management mode of mollusciciding, and assess its snail control effect in field application, so as to provide the effective management interventions for improving the quality of mollusciciding in the field. METHODS: Engineering management of mollusciciding was performed. The snail distribution was surveyed before and after snail control with molluscicides and environmental modification, and the database was established. The snail control effect of the engineering management mode of mollusciciding was assessed. RESULTS: Engineering management mode of mollusciciding was conducted in 96.27% (1 033/1 073) of the total snail habitats in 6 counties (districts) of Yangzhou City from 2006 to 2011. After the implementation of engineering management mode, the mortality of snails increased from 65.07% before implementation to 87.16% (80.65%-89.38%), and significant difference was observed (chi2 = 4 623.297, P = 0). The reductions in occurrence rate of frames with snails and snail density and the corrected mortality of snails were 57.67% (49.27%-66.98%), 76.67% (76.13%-83.66%) and 86.58% (79.89%-88.89%), respectively, which were 1.45, 1.63 times and 1.37 times more than those before implementation. After the implementation of engineering management mode of mollusciciding for 3 years in Yangzhou City, all infected snails were eliminated. After 6 years of implementation, the number of settings with snails, snail areas, occurrence rate of frames with snails, means snail density decreased by 56.27%, 76.40%, 67.99% and 66.67%, respectively. CONCLUSIONS: High-quality molluscicide is the essential factor to ensure the molluscicidal effect, and engineering management mode of mollusciciding is an effective approach to improve the quality of snail control with molluscicides in the field.

Optimizing molluscicide treatment strategies in different control stages of schistosomiasis in the People's Republic of China.

BACKGROUND: The application of chemical molluscicides is still one of the most effective measures for schistosomiasis control in P. R. China. By applying diverse molluscicide treatment scenarios on different snail densities in the field, we attempted to understand the cost-effectiveness of molluscicide application so as to prescribe an optimal management approach to control intermediate host snail Oncomelania hupensis under acceptable thresholds based on the goal of the National Schistosomiasis Control Programme. METHODS: The molluscicidal field trial was carried out in the marshland of an island along the Yangtze River, Jiangsu province, P.R. China in October 2010. Three plots in the island representing low-density, medium-density and high-density groups were identified after the baseline survey on snail density. Each snail density plot was divided into four experimental units in which molluscicide (50% niclosamide ethanolamine salt wettable powder) was applied once, twice, trice and four times, respectively. The logistic regression model to correlate snail mortality rate with the covariates of number of molluscicidal treatment and snail density, and a linear regression model to investigate the relationship between cost-effectiveness and number of molluscicidal treatment as well as snail density were established. RESULTS: The study revealed that increase in the number of molluscicide treatments led to increased snail mortality across all three population density groups. The most cost-effective regimen was seen in the high snail density group with a single molluscicide treatment. For both high and low density groups, the more times molluscicide were applied, the less cost-effectiveness was. However, for the median density group, the level of cost-effectiveness for two applications was slightly higher than that in one time. CONCLUSIONS: We concluded that different stages of the national schistosomiasis control/elimination programme, namely morbidity control, transmission control and transmission interruption, should utilize different molluscicide treatment strategies to maximize cost-effectiveness.

[Novel strategies and technologies to achieve the transmission control of schistosomiasis in Jiangsu Province].

According to the requirements of the Mid- and Long-term Plan for Prevention and Control of Schistosomiasis in China and based on the actual situation of schistosomiasis control in Jiangsu Province, this paper demonstrates the new technologies achieved by the scientific innovation and the novel control strategies including integrated control in key regions and control of key populations and surveillance and forecast of key water regions since 2004, with the emphasis on the control and elimination of infected Oncomelania snails. Such strategies and technologies implemented the result in continuous decrease in the endemic situation of schistosomiasis in the province, and the whole province achieved the goal of schistosomiasis transmission control in late 2010.

[Burden of disease in Schistosomiasis japonica. IV. Community socioeconomic determinants of chronic schistosomiasis].

OBJECTIVE: To explore the socioeconomic determinants of chronic schistosomiasis japonica at a community (village) level. METHODS: The socioeconomic and epidemiological data (Years lived with disability, YLDs) came from the thematic research carried out in two schistosome-endemic counties, Dangtu and Hanshou, in lake areas between 2004 and 2005. A concentration index was calculated and used to assess the health inequalities between socioeconomic statuses. The community risk factors relating to chronic schistosomiasis were explored by the multiple regression model. RESULTS: The concentration index was -0.12 of Dangtu County and 0.03 of Hanshou County which indicated that there were no health inequalities due to schistosomiasis between communities with different socioeconomic statuses. There was no linear relationship between the economic levels and YLDs of chronic schistosomiasis. The results of multiple regression model showed that the distance from village to schistosome-infested water (P < 0.01) and wet land area per capita (P < 0.05) were significantly related to YLDs of chronic schistosomiasis. CONCLUSION: There is non-linear relationship between socioeconomic levels and YLDs of chronic schistosomiasis, but the distance from village to schistosome-infested water and wet land area per capita are significantly related to the latter.