[Construction of a schistosomiasis transmission risk assessment system in Wuhan City based on analytic hierarchy process].

OBJECTIVE: To construct a schistosomiasis transmission risk assessment system in Wuhan City and preliminary evaluate its application effect, so as to promote the rational allocation of schistosomiasis control resources and accelerate the progress towards schistosomiasis elimination. METHODS: The schistosomiasis risk assessment indicators were collected through referring schistosomiasis surveillance data of Wuhan City from 2014 to 2020, literature review and expert interviews. Indicators within each criterion and sub-criterion were screened using the Delphi method, and a hierarchical structure model was created based on analytic hierarchy process. Quantitative assignment of each indicator was conducted according to relative importance, and the weight and combination weight of each criterion were calculated in each analytic hierarchy framework to create a schistosomiasis transmission risk assessment system, which was used for the schistosomiasis transmission risk assessment in 12 national schistosomiasis surveillance sites in Wuhan City. RESULTS: A three-level schistosomiasis transmission risk assessment system was preliminarily constructed, which included a target layer, 5 criterion layers and 21 sub-criterion layers. Of all indicators in the criterion layer, transmission route had the highest weight (0.433), followed by source of Schistosoma japonicum infection (0.294); and among all indicators in the sub-criterion layer, S. japonicum infection in Oncomelania hupensis and sentinel mice had the highest combination weight (0.125), followed by prevalence of S. japonicum infection in humans (0.091) and bovines (0.053), snail control by chemical treatment (0.049), positive rate of inquiry examinations (0.048), allocation of schistosomiasis control professionals (0.045), and areas of submerged snail-infested settings (0.041). Of the 12 national schistosomiasis surveillance sites in Wuhan City, there were 5 sites with weights of > 0.8, 4 sites with weights of 0.6 to 0.8, and 3 sites with weights of < 0.6 in 2020. CONCLUSIONS: A schistosomiasis transmission risk assessment system has been constructed based on analytic hierarchy process in Wuhan City, which may provide a evidence-based basis for health resource allocation and decision-making for schistosomiasis control.

Cost-effectiveness analysis of the integrated control strategy for schistosomiasis japonica in a lake region of China: a case study.

BACKGROUND: Schistosomiasis japonica remains an important public health concern due to its potential to cause severe outcomes and long-term sequelae. An integrated control strategy implemented in the Peoples' Republic of China has been shown to be effective to control or interrupt the transmission of schistosomiasis. The objective of this study is to estimate the disease burden of schistosomiasis and assess the cost-effectiveness of the integrated control strategy focused on different major interventions at three stages for schistosomiasis control in a lake setting, to provide reference for policy making or planning. METHODS: Annual cost data of schistosomiasis control during 2009-2019 were obtained from the control program implementers in Jiangling County, Hubei Province, China. Economic costs are provided in constant 2009 Chinese Yuan (CNY). Epidemiological data of schistosomiasis were collected from the Jiangling county station for schistosomiasis control. Disease burden of schistosomiasis was assessed by calculating years of life lost (YLLs) owing to premature death, years lived with disability (YLDs) and disability-adjusted life years (DALYs). DALYs were calculated as the sum of YLLs and YLDs. We then conducted a rudimentary cost-effectiveness analysis by determining the ratio by dividing the difference between the average cost of integrated control strategy at transmission control (2013-2016) or transmission interruption (2017-2019) and the average cost at stage of infection control (2009-2012) with the difference between the DALYs of schistosomiasis at different control stages. Descriptive statistics on the costs and DALYs were used in the analysis. RESULTS: The total economic costs for schistosomiasis control in Jiangling County from 2009 to 2019 were approximately CNY 606.88 million. The average annual economic costs for schistosomiasis prevention and control at stages of infection control (2009-2012), transmission control (2013-2016), and transmission interruption (2017-2019) were approximately CNY 41.98 million, CNY 90.19 million and CNY 26.06 million respectively. The overall disease burden caused by schistosomiasis presented a downward trend. Meanwhile, the disease burden of advanced cases showed an upward trend with the DALY increased from 943.72 to 1031.59 person-years. Most disease burden occurred in the age group over 45 years old (especially the elderly over 60 years old). Taking the infection control stage as the control, the incremental cost-effectiveness ratio of integrated control strategy was CNY 8505.5 per case averted, CNY 60 131.6 per DALY decreased at transmission control stage and CNY -2217.6 per case averted, CNY -18 116.0 per DALY decreased at transmission interruption stage. CONCLUSIONS: The disease burden of schistosomiasis decreased significantly with the implementation of the integrated prevention and control strategy. Surveillance and management on elder population should be strengthened to decrease diseases burden. There remains a need for well-conducted studies that examine the long-term cost-effectiveness of the integrated control strategy for schistosomiasis. GRAPHIC ABSTARCT.

Contributions and achievements on schistosomiasis control and elimination in China by NIPD-CTDR.

Being a zoonotic parasitic disease, schistosomiasis was widely spread in 12 provinces of Southern China in the 1950s, severly harming human health and hindering economic development. The National Institute of Parasitic Diseases at the Chinese Center for Diseases Control and Prevention, and Chinese Center for Tropical Diseases Research (NIPD-CTDR), as the only professional institution focussing on parasitic diseases at the national level, has played an important role in schistosomiasis control in the country. In this article, we look back at the changes of schistosomiasis endemicity and the contribution of NIPD-CTDR to the national schistosomiasis control programme. We review NIPD-CTDR's activities, including field investigations, design of control strategies and measures, development of diagnostics and drugs, surveillance-response of endemic situation, and monitoring & evaluation of the programme. The NIPD-CTDR has mastered the transmission status of schistosomiasis, mapped the snail distribution, and explored strategies and measures suitable for different types of endemic areas in China. With a good understanding of the life cycle of Schistosoma japonicum and transmission patterns of the disease, advanced research carried out in the NIPD-CTDR based on genomics and modern technology has made it possible to explore highly efficient and soft therapeutic drugs and molluscicides, making it possible to develop new diagnostic tools and produce vaccine candidates. In the field, epidemiological studies, updated strategies and targeted intervention measures developed by scientists from the NIPD-CTDR have contributed significantly to the national schistosomiasis control programme. This all adds up to a strong foundation for eliminating schistosomiasis in China in the near future, and recommendations have been put forward how to reach this goal.

[Approaches used for assessment of the burden of advanced schistosomiasis japonica: a comparative study].

OBJECTIVE: To compare the approaches used for the assessment of disability adjust life years (DALYs) for advanced schistosomiasis japonica, so as to provide scientific evidence for accurate assessment of the burden of advanced schistosomiasis japonica. METHODS: The patients with advanced schistosomiasis japonica receiving treatment and assistance programs in Hunan Province in 2017 were enrolled, and the years lived with disability (YLD) for the patients with advanced schistosomiasis japonica was calculated using the common global burden of disease (GBD) estimation method, the modified GBD method with addition of common syndromes of advanced schistosomiasis japonica, and the quality of life assessment method. RESULTS: The YLDs of patients with advanced schistosomiasis japonica, the mean YLDs per capita, and the percentages of YLD were 673.94, 728.77 person-years and 1 761.99 person-years; 0.181, 0.196 person-years and 0.474 person-years; and 10.61, 11.48 person-years per 100 thousand persons and 27.75 person-years per 100 thousand persons with the common GBD method, modified GBD method and the quality of life method, respectively. The YLDs of the patients with advanced schistosomiasis japonica in Hunan Province estimated with the modified GBD method and the quality of life method were 8.14% and 2.61 times higher than that with the common GBD method. Of the major symptoms included in the calculation, the 5 symptoms with the greatest contribution to the burden of advanced schistosomiasis japonica included ascites, moderate anemia, severe anemia, diarrhea and hematochezia. CONCLUSIONS: The quality of life method may more comprehensively assess the YLDs in patients with advanced schistosomiasis japonica than the common and modified GBD methods.

A cross-sectional survey comparing a free treatment program for advanced schistosomiasis japonica to a general assistance program.

The prevalence and intensity of schistosomiasis has dropped dramatically in China due to an effective integrated control program. However, advanced schistosomiasis is becoming a key challenge on the road to elimination. The aims of this study were to compare the disease condition between advanced cases under the general assistance program (GAP) and free treatment program (FTP) and to determine whether the FTP should be popularized to provide an objective reference for policymakers in China's advanced schistosomiasis control program. One hundred and ninety-four patients with schistosomiasis japonica who were enrolled in the GAP or FTP participated in this study. Little significant difference was observed in the potential confounders, including general characteristics, comorbidities, and lifestyle, indicating a similar effect on the pathology of liver damage caused by schistosome infection. There was no apparent difference in the incidence of common clinical symptoms. Furthermore, no significant difference was observed in the ultrasound findings, implying that the GAP and FTP groups shared a similar degree of liver lesion. With the exception of the abnormal rates of aspartate aminotransferase (AST), alkaline phosphatase (ALP), and hyaluronic acid (HA), the other serological indicators were comparable between the groups. Overall, the FTP is not a better option for controlling advanced schistosomiasis in China. It is important to reveal the precise mechanism underlying the pathogenesis of advanced schistosomiasis so that specific approaches to treating and preventing the development of advanced schistosomiasis can be developed and schistosomiasis can be eliminated 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.

Schistosomiasis in a migrating population in the lake region of China and its potential impact on control operation.

Coverage of migrating people in schistosomiasis control program is a growing concern in China. Schistosomiasis caused by Schistosoma japonicum is still one of the major infectious diseases of public health importance in China though tremendous efforts have been made to control the transmission over the past decades. Along with the rapid social-economic development, migrant population has been remarkably increasing across the country. The infected migrants may introduce a new souse of infection to endemic areas or the areas where the transmission had been controlled or interrupted but the intermediate host Oncomelania snail is still present. Preliminary studies for surveillance on schistosomiasis prevalence in migrants were reported, but there is little basic information provided. We carried out an investigation on the prevalence in immigrants, emigrants and permanent residents in three villages of Hunan province located in the main endemic area of lake region, and analyzed the potential impact of migration on control practice. In the study villages, the migrant population accounts for 53.6% of the total. Schistosoma infection was detected by modified Kato-Katz method and miracidium hatching test. Questionnaire survey was conducted comprising knowledge of disease and its transmission, water contact, personal protective measures, and whether examined and treated after water contact. The survey indicated that the migrants and permanent residents had similar life style, and the majority of them experienced water contact in agricultural work or routine life activities. However, the infection rate in immigrants was significantly higher than that in permanent residents. It was also found that the migrants had significantly less knowledge about the disease than the permanent residents, and took no personal protective measures. This is due to that the control program could not cover the migrants when they were absent at the time the program being implemented. The present study suggested that the surveillance and intervention for migrants, immigrants in particular, should be included and strengthened in schistosomiasis control program and a feasible scheme be developed.

Integrated control programmes for schistosomiasis and other helminth infections in P.R. China.

The prevalence of human schistosomiasis and soil-transmitted helminthiasis (STH) has decreased significantly in the People's Republic of China (P.R. China), particularly after 2005 when the national control programmes were reinforced by forming of integrated control strategies. Furthermore, social-economic development also contributed to the decrease of schistosome and soil-transmitted helminth infections. The prevalence of the zoonotic helminthiasis, including clonorchiasis and echinococcosis, on the other hand, is either underestimated or has in fact increased due to changes in social and environmental factors. In comparison with the control strategies in force and their effects on those four kinds of helminthiasis, the challenges and control priorities for the potential transfer from control to elimination of each disease is reviewed, to provide evidence for policy-makers to act upon.

[Assessment of schistosomiasis endemic situation in national surveillance sites in Hubei Province from 2005 to 2010].

OBJECTIVE: To assess the schistosomiasis endemic situation in the national surveillance sites in Hubei Province, so as to provide the evidence for the prevention and control of schistosomiasis. METHODS: According to the national surveillance protocol, a longitudinal surveillance of endemic situation of schistosomiasis was carried out in 16 national surveillance sites from 2005 to 2010. RESULTS: In general, the positive rates of IHA, Kato-Katz technique and infection rates of Schistosoma japonicum decreased from 15.67%, 10.93% and 1.71% in 2005 to 10.48%, 8.54% and 0.90% in 2010, and declined by 33.12%, 22.70% and 47.95%, respectively. The infection rates of S. japonicum of the male were higher than that of the female, and the peak infection rates were in the groups aged above 30 years. The endemic situation of fishermen and farmers were relatively serious. The infection rates of S. japonicum in cattle decreased from 11.69% in 2005 to 1.41% in 2010, and declined by 88.01% (χ2 = 298.79, P < 0.001). The areas with infected Oncomelania hupensis snails, the densities of living snails, the rates of infected snails and the densities of infected snails decreased by 90.88%, 61.66%, 80.00% and 92.00%, respectively. CONCLUSION: The schistosomiasis endemic situation in the national surveillance sites in Hubei Province mitigates in 6 years, but the prevention is still a very daunting task.

Impact and cost-effectiveness of a comprehensive Schistosomiasis japonica control program in the Poyang Lake region of China.

Schistosomiasis japonica remains a significant public-health problem in China. This study evaluated cost-effectiveness of a comprehensive schistosomiasis control program (2003-2006). The comprehensive control program was implemented in Zhangjia and Jianwu (cases); while standard interventions continued in Koutou and Xiajia (controls). Incurred costs were documented and the schistosomiasis comprehensive impact index (SCI) and cost-effectiveness ratio (Comprehensive Control Program Cost/SCI) were applied. In 2003, prevalence of Schistosoma japonicum infection was 11.3% (Zhangjia), 6.7% (Jianwu), 6.5% (Koutou), and 8.0% (Xiajia). In 2006, the comprehensive control program in Zhangjia and Jianwu reduced infection to 1.6% and 0.6%, respectively; while Koutou and Xiajia had a schistosomiasis prevalence of 3.2% and 13.0%, respectively. The year-by-year SCIs in Zhangjia were 0.28, 105.25, and 47.58, with an overall increase in cost-effectiveness ratio of 374.9%-544.8%. The SCIs in Jianwu were 16.21, 52.95, and 149.58, with increase in cost-effectiveness of 226.7%-1,149.4%. Investment in Koutou and Xiajia remained static (US$10,000 unit cost). The comprehensive control program implemented in the two case villages reduced median prevalence of schistosomiasis 8.5-fold. Further, the cost effectiveness ratio demonstrated that the comprehensive control program was 170% (Zhangjia) and 922.7% (Jianwu) more cost-effective. This work clearly shows the improvements in both cost and disease prevention effectiveness that a comprehensive control program-approach has on schistosomiasis infection prevalence.

[Current status of human Schistosoma japonicum infection and reinfection in marshland and lake regions of Xinjian County, Jiangxi Province, China].

OBJECTIVE: To understand the dynamics of human infection and reinfection of Schistosoma japonicum after chemotherapy in marshland and lake endemic regions so as to provide the evidence for developing a cost-effective control strategy. METHODS: From 2007 to 2011, the schistosome infection, intensities and reinfection of population were investigated and the results were analyzed dynamically in Caohui Village, a national schistosomiasis surveillance site in Changyi Township, Xinjian County, Jiangxi Province, China. RESULTS: The schistosome infection rate was 3.55% and the mean intensity was 1.56 in 2007, and the schistosome infection rate was 1.52% and the mean intensity was 1.60 in 2011. The reinfection rates were 2.70%, 9.09% and 2.47% in 2009, 2010, and 2011, respectively. CONCLUSION: The schistosomiasis endemic situation shows a downtrend in the village. However, the reinfection is still serious; therefore, we should strengthen the research of risk factors of reinfection and control them.

[Assessment of effect and quality control for parasitological tests in national schistosomiasis surveillance sites].

OBJECTIVE: To understand the ability of pathogenic diagnosis for schistosomiasis japonica in the national surveillance sites and evaluate the effect of stool hatching method in the field, so as to provide the evidence for establishing a quality control system of pathogenic diagnosis of schistosomiasis in the surveillance sites. METHODS: The data pertaining to the parasitological diagnosis of the residents with positive serological tests were collected in 81 national surveillance sites of 12 provinces in 2011, and the effects of the Kato-Katz technique and stool hatching method were evaluated and compared. The incubation quality control samples made by the national schistosomiasis diagnosis reference laboratory were detected by both Kato-Katz technique and stool hatching method using the single-blind method, and the results were analyzed and compared for the coincidence rate, misdiagnosis rate and missing diagnosis rate in all the county laboratories in 2012. RESULTS: A total of 3 780 sero-positive residents were tested by using the Kato-Katz technique and stool hatching method in the 81 national surveillance sites in 2011, 127 persons were double egg-positive, 3 513 persons were double egg-negative, and the total coincidence rate was 96.30%. Totally 173 infected people were diagnosed by using the Kato-Katz technique and the positive detection rate was 4.58%; 221 infected people were diagnosed by using the stool hatching method and the positive detection rate was 5.85%. A total of 267 positive people were diagnosed by the Kato-Katz technique or the stool hatching method or both and the total positive detection rate was 7.06%, which was higher by 54.15% than that by using the single Kato-Katz technique (chi2 = 21.32, P < 0.01). In 2012, of 240 standard incubation quality control samples (160 positives, 80 negatives) detected by the technicians from the 80 surveillance sites, 105 samples were positive and 67 samples were negative, with a total coincidence rate of 71.67% (172/240) and a total missing diagnosis rate of 34.38% (55/160). Among them, the missing rate of the strong positive samples was 32.50% (26/80), the missing rate of the weakly positive samples was 36.25% (29/80), and the misdiagnosis rate of the negative samples was 16.25% (13/80). The detection rates of the incubation quality control samples were 61.11%, 80.00%, 77.08%, 90.48%, 58.33% and 59.26% in the surveillance sites of six provinces, including Anhui, Hubei, Hunan, Jiangsu, Jiangxi and Sichuan provinces, respectively, and a significant difference was found (chi2 = 14.27, P < 0.05). CONCLUSIONS: The detection efficiency of the stool hatching method is superior to that of the Kato-Katz technique in the field. However, the levels of the technical personnel for the stool hatching method are relatively low in most of the surveillance sites. Therefore, the technical training should be strengthened.

A mathematical model for the transmission of Schistosoma japonicum in consideration of seasonal water level fluctuations of Poyang Lake in Jiangxi, China.

BACKGROUND: Poyang Lake, the largest fresh water lake in China, is the major transmission site of Schistosoma japonicum in China. Epidemics of schistosomiasis japonica have threatened the health of residents and stunted social-economic development there. OBJECTIVE: This article aims at evaluating the effect of various control measures against schistosomiasis: selective mass treatment (ST), targeted mass treatment (TT), mass treatment for animal reservoirs (MT), and health education (HE), on reduction of the prevalence through simulations based on a mathematical model. METHODS: We proposed a mathematical model, which is a system of ordinary differential equations for the transmission of S. japonicum among humans, bovines, and snails. The model takes into account the seasonal variation of the water level of Poyang Lake that is caused by the backflow of the Yangtze River and inflow from five small rivers, which influences the transmission of S. japonicum. For the purpose of dealing with the age-specific prevalence and intensity of infection, the human population was classified into four age categories in the model. We carried out several simulations resulting from the execution of ST and TT for elementary school children (E Sch), and combinations of ST, MT, and HE. RESULTS: The simulations indicated that all of the control measures only for humans had a trend of revival after interruption, and a combination of ST and MT has a significant effect on reducing human infection. Although TT and HE had a significant effect on the prevalence in the E Sch group, it had little effect on the overall human population. CONCLUSION: The simulations indicate that measures targeted to bovines such as chemotherapy besides humans will be vital to eliminate the transmission of S. japonicum in the Poyang Lake region. Moreover, it is desirable to improve health education for fishermen and herdsmen.

[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.

[Burden of disease in schistosomiasis japonica. I. Calculation and evaluation of years lived with disability of chronic schistosomiasis].

OBJECTIVE: To discuss the evaluation index of the disease burden of chronic schistosomiasis and its calculation methods. METHODS: The epidemiological data came from the thematic research carried out in two schistosome-endemic counties in lake areas between 2004 and 2005. The specific prevalence rates by age group, gender and endemic type were calculated. According to the age-specific disability weight obtained in the thematic research, the years lived with disability (YLDs) and the rates of YLD of stratified samples by age and gender, and the total YLDs of the two counties were calculated. RESULTS: The total YLDs were 1 056.26 and 3 967.43 person-years in Dangtu and Hanshou counties, respectively. The contributing rate of Grade I type village to the total YLDs of two counties was 37.95% (40.08% in Dangtu and 37.39% in Hanshou). For different stratums by age and gender, the older ones and male tended to have larger YLDs. Compared to the non-endemic areas, chronic schistosomiasis brought an average extra of 4.398 and 1.505 years per 1 000 person to population in Dangtu and Hanshou counties, respectively. CONCLUSION: The evaluation to YLDs of chronic schistosomiasis is helpful for prioritizing intervention areas and population, as well as providing a new index for the evaluation of effectiveness of control measures.

[Burden of disease in schistosomiasis japonica. II. Measurement of health inequalities due to chronic schistosomiasis].

OBJECTIVE: To measure and evaluate the health inequalities due to chronic schistosomiasis japonica. METHODS: Based on years lived with disability (YLD) caused by chronic schistosomiasis, a concentration index and Gini index, along with a concentration curve and Lorenz curve, the health inequalities between sexes, age groups or endemicities were identified and quantified. RESULTS: The age concentration index was 0.395 of females and 0.380 of males, with no significant difference between them. More than 60% of YLD was contributed by those aged > or = 45 years old who accounted for about a third of total population in both sexes. Gini index was 0.666 of Dangtu County and 0.451 of Hanshou County, and 60% of YLD was contributed by the highly endemic villages. CONCLUSIONS: The concentration index and Gini index could quantify the magnitude of health inequalities well. The priority of morbidity control should be given to those aged > or = 45 years old and living in highly endemic villages.

Tools to support policy decisions related to treatment strategies and surveillance of Schistosomiasis japonica towards elimination.

BACKGROUND: Appropriate diagnostics to monitor disease trends and assess the effectiveness and impact of interventions are essential for guiding treatment strategies at different thresholds of schistosomiasis transmission and for certifying elimination. Field validation of these assays is urgently needed before they can be adopted to support policy decisions of the national programme for control and elimination of schistosomiasis in P.R. China. We compared the efficacy and utility of different immunoassays in guiding control strategies and monitoring the endemic status of S. japonicum infections towards elimination. METHODOLOGY/PRINCIPAL FINDINGS: A cross-sectional survey was conducted in seven villages with different transmission intensities settings to assess the performance and utility of three immunoassays, e.g., an indirect hemagglutination assay (IHA_JX), an enzyme linked immunosorbent assay (ELISA_SZ), and a dot immunogold filtration assay (DIGFA_SH). 6,248 individuals aged 6-65 years old who gave consent and supplied their stool and blood samples were included for data analysis. Results showed that ELISA_SZ performed significantly higher sensitivity (95.45%, 95%CI: 92.94-97.97%) than IHA_JX (87.59%, 95%CI: 83.51-91.49%) and DIGFA_SH (79.55%, 95%CI: 74.68-84.41%), especially in subgroups with very low infection intensity. The specificity of ELISA_SZ, IHA_JX, DIGFA_SH in 6-9 year olds with occasional exposure was nearly 90%. DIGFA_SH performed the highest screening efficacy for patients among three assays with overall positive predicative value of 13.07% (95%CI: 11.42-14.72%). We found a positive correlation of antibody positive rate of IHA_JX with results of stool examination in age strata (r = 0.70, P<0.001). Seropositivity of IHA_JX in children aged 6-9 years old showed an excellent correlation with prevalence of schistosome infection in the seven communities (r = 0.77, P<0.05). CONCLUSIONS/SIGNIFICANCE: Studies suggest that ELISA_SZ could be used to guide selective chemotherapy in moderate or low endemic regions. IHA_JX could be used to as a surveillance tool and for certifying elimination of schistosomiasis through monitoring children as a sentinel population.

Toward sustainable and comprehensive control of schistosomiasis in China: lessons from Sichuan.

Triggered by a fascinating publication in the New England Journal of Medicine detailing China's new multi-pronged strategy to control and eventually interrupt the transmission of Schistosoma japonicum, this PLoS Neglected Tropical Diseases Debate critically examines the generalizability and financial costs of the studies presented from the marshlands of the lake region. Edmund Seto from the University of California and colleagues emphasize that the epidemiology and control of schistosomiasis varies according to the social-ecological context. They conjecture that the successful intervention packages piloted in the lake region is not fully fit for the hilly and mountainous environments in Sichuan and Yunnan provinces, and hence call for more flexible, setting-specific, and less expensive control strategies. In response, Xiao-Nong Zhou from the National Institute of Parasitic Diseases at the Chinese Center of Disease Control and Prevention and colleagues explain the steps from designing pilot studies to the articulation and implementation of a new national control strategy through a careful process of scaling-up and adaptations. Finally, the two opponents converge. The need for integrated, intersectoral, and setting-specific control measures is stressed, supported by rigorous surveillance and continuous research. Experiences and lessons from China are important for shaping the schistosomiasis elimination agenda.

[Risk factors of schistosomiasis transmission in marshland and lake regions in midstream of Yangtze River].

OBJECTIVE: To study the risk factors of schistosomiasis related to household economic condition and individual behavior in marshland and lake regions, so as to provide evidences for schistosomiasis control. METHODS: Six villages were sampled with the stratified cluster sampling method, 2 339 villagers from 1 247 households were surveyed by a questionnaire and meanwhile their sera were assayed for schistosomiasis by IHA. The Logistic regression was used to analyze the relationship between the results of serological examinations and risk factors. RESULTS: The Logistic regression model fitted well (R2 = 0.598 4) and it indicated that there existed a regressive relationship between the antibody positive rate and the endemic situation of village, family economic status, age, education level and infection history of schistosomiasis. CONCLUSION: Suitable measures should be made in according to the local economic situation, endemic type and population to control the transmission of schistosomiasis effectively.

Spatially explicit agent-based modelling for schistosomiasis transmission: human-environment interaction simulation and control strategy assessment.

BACKGROUND: As the transmission of many other parasitic diseases, the transmission of schistosomiasis is a complex process governed by natural, socio-economic factors and human life style. Based on the life cycle of Schistosoma japonicum, some models have been developed. However, the human-environment interaction, especially through agricultural activities, has not been explicitly modeled in previous efforts. OBJECTIVE: To understand the effect of agricultural land use and other social economic factors on schistosomiasis transmission by explicitly including agricultural land use, human water contact behaviors, feces processing, and control strategies in a multi-level agent based model. METHODS: We proposed a spatially explicit agent-based schistosomiasis transmission model and describe its design and implementation. We chose one endemic village near Xichang, China to construct a virtual environment with the "patch". We modeled the behaviors (water contact, feces contamination and disease control) of various agents (villages, households and individuals) in the environment and predicted the potential infection risk of human and snails in space and time with consideration of socio-economic and human behavioral factors. RESULTS: We obtained simulation results based on different scenarios of schistosomiasis control involving two dominant types of land use and four types of control measures. We also compared the effect of different timing on chemotherapy treatment. CONCLUSIONS: The scheme for multi-level agent simulation including human-environment interaction behaviors in schistosomiasis transmission is a useful framework for assessment of different control strategies.