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      Tools to Support Policy Decisions Related to Treatment Strategies and Surveillance of Schistosomiasis Japonica towards Elimination

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          Abstract

          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.

          Author Summary

          Immunodiagnostic assays are widely applied in the field to control schistosomiasis in P.R. China as the prevalence and infection intensity of schistosome infections decrease. Field evaluations are urgently needed before they can be adopted to support policy decisions of the national programme for the control and elimination of schistosomiasis in P.R. China. We carried out a large scale cross-sectional survey in field settings with different transmission situations to validate immunodiagnostic tools that can be used to formulate new schistosomiasis elimination strategy in P.R. China. Regarding stool examination as gold reference, the validity and screening efficacy of each immunodiagnostic kit were calculated and compared with each other. The association of the prevalence of schistosomiasis and antibody positive rates determined by immunoassays were analyzed using Pearson's correlation coefficient values. The study indicates that which test to use with the elimination strategy is dependent on the purpose of testing, the endemic status of community and the resources available. And more sensitive methods need to be explored and used to target infected individuals for treatment or to eliminate schistosomiasis.

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          Most cited references66

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          The global status of schistosomiasis and its control.

          Schistosomiasis is being successfully controlled in many countries but remains a major public health problem, with an estimated 200 million people infected, mostly in Africa. Few countries in this region have undertaken successful and sustainable control programmes. The construction of water schemes to meet the power and agricultural requirements for development have lead to increasing transmission, especially of Schistosoma mansoni. Increasing population and movement have contributed to increased transmission and introduction of schistosomiasis to new areas. Most endemic countries are among the least developed whose health systems face difficulties to provide basic care at the primary health level. Constraints to control include, the lack of political commitment and infrastructure for public health interventions. Another constraint is that available anti-schistosomal drugs are expensive and the cost of individual treatment is a high proportion of the per capita drug budgets. There is need for increased support for schistosomiasis control in the most severely affected countries.
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            The public health significance and control of schistosomiasis in China--then and now.

            The description of schistosomiasis in China dates back more than two millennia. The disease caused social and economic hardship, and the rates of morbidity and mortality were high. In the mid 1950s, when China's population was approximately 600 million, an estimated 11.6 million people were infected with Schistosoma japonicum. Hence, a national control programme was launched, with an emphasis on intermediate host snail control by means of environmental management. Over the past 50 years, the national control programme has made great progress and praziquantel-based morbidity control became the mainstay of control. In 2000, the number of infected people had been reduced to an estimated 694,788, the snail-infested area has been abridged by over 75%, and the disease had been eliminated in five of the 12 previously endemic provinces. Between the mid 1980s and 2003, the criteria of transmission interruption have been reached in 260 counties (60.0%), transmission control has been achieved in 63 counties (14.5%), but the disease was still endemic in the remaining 110 counties (25.4%). Comparison between the number of cases in 2000 and 2003 suggests that schistosomiasis has re-emerged; an estimated 843,011 people were infected with S. japonicum in 2003. Here, we provide a short historical account of the pubic health significance of schistosomiasis in China, highlight the progress made to date with the national control programme, and place particular emphasis on the most recent trends. Finally, we discuss remaining challenges for schistosomiasis control with the ultimate goal of disease elimination.
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              A strategy to control transmission of Schistosoma japonicum in China.

              Schistosoma japonicum causes an infection involving humans, livestock, and snails and is a significant cause of morbidity in China. We evaluated a comprehensive control strategy in two intervention villages and two control villages along Poyang Lake in the southeastern province of Jiangxi, where annual synchronous chemotherapy is routinely used. New interventions, implemented from 2005 through 2007, included removing cattle from snail-infested grasslands, providing farmers with mechanized farm equipment, improving sanitation by supplying tap water and building lavatories and latrines, providing boats with fecal-matter containers, and implementing an intensive health-education program. During the intervention period, we observed changes in S. japonicum infection in humans, measured the rate of infection in snails, and tested the infectivity of lake water in mice. After three transmission seasons, the rate of infection in humans decreased to less than 1.0% in the intervention villages, from 11.3% to 0.7% in one village and from 4.0% to 0.9% in the other (P<0.001 for both comparisons). The rate of infection in humans in control villages fluctuated but remained at baseline levels. In intervention villages, the percentage of sampling sites with infected snails decreased from 2.2% to 0.1% in one grassland area and from 0.3% to no infection in the other (P<0.001 for both comparisons). The rate of infection in mice after exposure to lake water decreased from 79% to no infection (P<0.001). A comprehensive control strategy based on interventions to reduce the rate of transmission of S. japonicum infection from cattle and humans to snails was highly effective. These interventions have been adopted as the national strategy to control schistosomiasis in China. 2009 Massachusetts Medical Society
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                Author and article information

                Contributors
                Role: Editor
                Journal
                PLoS Negl Trop Dis
                plos
                plosntds
                PLoS Neglected Tropical Diseases
                Public Library of Science (San Francisco, USA )
                1935-2727
                1935-2735
                December 2011
                20 December 2011
                : 5
                : 12
                : e1408
                Affiliations
                [1 ]National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, People's Republic of China
                [2 ]Jiangxi Provincial Institute of Parasitic Diseases, Nanchang, People's Republic of China
                [3 ]Anhui Provincial Institute of Parasitic Diseases, Hefei, People's Republic of China
                [4 ]Hubei Provincial Institute of Parasitic Diseases, Wuchang, People's Republic of China
                [5 ]Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, People's Republic of China
                [6 ]Diagnostics Research, London School of Hygiene and Tropical Medicine, London, United Kingdom
                Institute of Tropical Medicine (NEKKEN), Japan
                Author notes

                Conceived and designed the experiments: X-NZ JX J-XC RWP. Performed the experiments: X-NZ J-XC RWP H-GC T-PW X-BH D-DL Q-ZW LT J-GG X-HW TF J-XC JG S-HC HL Z-DW. Analyzed the data: X-NZ JX H-GC T-PW X-BH D-DL J-GG X-HW Z-DW RWP. Contributed reagents/materials/analysis tools: X-NZ JX RWP D-DL Q-ZW LT TF J-XC JG S-HC HL. Wrote the paper: X-NZ JX RWP.

                Article
                PNTD-D-11-00525
                10.1371/journal.pntd.0001408
                3243709
                22206024
                035c6fc6-fac3-4ba0-be0a-f6ac357ff586
                Zhou et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
                History
                : 1 June 2011
                : 15 October 2011
                Page count
                Pages: 8
                Categories
                Research Article
                Medicine
                Diagnostic Medicine
                Test Evaluation
                Infectious Diseases
                Neglected Tropical Diseases
                Schistosomiasis
                Parasitic Diseases
                Schistosomiasis
                Science Policy
                Research Assessment
                Research Monitoring
                Research Laboratories
                Government Laboratories

                Infectious disease & Microbiology
                Infectious disease & Microbiology

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