Optimized strategy for schistosomiasis elimination: results from marginal benefit modeling.

BACKGROUND: Poverty contributes to the transmission of schistosomiasis via multiple pathways, with the insufficiency of appropriate interventions being a crucial factor. The aim of this article is to provide more economical and feasible intervention measures for endemic areas with varying levels of poverty. METHODS: We collected and analyzed the prevalence patterns along with the cost of control measures in 11 counties over the last 20 years in China. Seven machine learning models, including XGBoost, support vector machine, generalized linear model, regression tree, random forest, gradient boosting machine and neural network, were used for developing model and calculate marginal benefits. RESULTS: The XGBoost model had the highest prediction accuracy with an R2 of 0.7308. Results showed that risk surveillance, snail control with molluscicides and treatment were the most effective interventions in controlling schistosomiasis prevalence. The best combination of interventions was interlacing seven interventions, including risk surveillance, treatment, toilet construction, health education, snail control with molluscicides, cattle slaughter and animal chemotherapy. The marginal benefit of risk surveillance is the most effective intervention among nine interventions, which was influenced by the prevalence of schistosomiasis and cost. CONCLUSIONS: In the elimination phase of the national schistosomiasis program, emphasizing risk surveillance holds significant importance in terms of cost-saving.

The Efficiency of Commercial Immunodiagnostic Assays for the Field Detection of Schistosoma japonicum Human Infections: A Meta-Analysis.

Although great strides have been achieved, schistosomiasis japonica remains a major public health concern in China. Immunodiagnostics have been widely accepted as the first choice in large-scale screening of Schistosoma japonicum human infections, and indirect hemagglutination test (IHA), enzyme-linked immunosorbent assay (ELISA), and dipstick dye immunoassay (DDIA) are currently the three most common immunological tests for the diagnosis of S. japonicum human infections in China. This meta-analysis aimed to comprehensively assess the performance of IHA, ELISA, and DDIA for the field diagnosis of S. japonicum human infections. A total of 37 eligible publications were enrolled in the final analysis, including 29 Chinese publications and 8 English publications. No significant heterogeneities were detected among the studies reporting ELISA (I2 = 88%, p < 0.05), IHA (I2 = 95%, p < 0.05), or DDIA (I2 = 84%, p < 0.05). DDIA showed the highest pooled sensitivity (90.8%, 95% CI: 84.6% to 94.7%) and IHA presented the highest pooled specificity for detection of S. japonicum human infections (71.6%, 95% CI: 65.9% to 76.7%). Summary receiver operating characteristic (SROC) curve analysis showed that IHA exhibited the highest area under the SROC curve (AUC) (0.88, 95% CI: 0.85 to 0.9), and ELISA presented the lowest AUC (0.85, 95% CI: 0.82 to 0.88). Deeks' funnel plots indicated no publication bias. IHA presented the highest sensitivity in medium-endemicity regions and the highest specificity for diagnosis of S. japonicum human infections in low-endemicity regions, and ELISA showed the highest diagnostic sensitivity in high-endemicity regions and the highest specificity in medium-endemicity regions, while DDIA exhibited the highest diagnostic sensitivity in high-endemicity regions and the highest specificity in low-endemicity regions. IHA and DDIA presented a higher efficiency for the diagnosis of S. japonicum human infections in marshland and lake regions than in hilly and mountainous regions, while ELISA showed a comparable diagnostic sensitivity between in marshland and lake regions and hilly and mountainous regions (88.3% vs. 88.6%), and a higher specificity in marshland and lake regions than in hilly and mountainous regions (60% vs. 48%). Our meta-analysis demonstrates a comparable diagnostic accuracy of IHA, ELISA, and DDIA for S. japonicum human infections, and the diagnostic sensitivity and specificity of IHA, ELISA, and DDIA vary in types and infection prevalence of endemic regions. DDIA combined with IHA is recommended as a tool for screening chemotherapy targets and seroepidemiological surveys during the stage moving towards schistosomiasis elimination in China. Further studies to examine the effectiveness of combinations of two or three immunological tests for diagnosis of S. japonicum human infections are warranted.

Rapid Assessment on Potential Risks of Schistosomiasis Transmission - 7 PLADs, China, 2019 and 2021.

WHAT IS ALREADY KNOWN ABOUT THIS TOPIC?: Oncomelania hupensis(O. hupensis) and livestock are main infection sources of schistosomiasis. The schistosome infected O. hupensis and livestock's feces are important risk factors in the transmission of schistosomiasis. WHAT IS ADDED BY THIS REPORT?: The potential risks of schistosomiasis transmission remain prevalent, giving an early warning to local government with information on existing transmission risks. It is expected that the effectiveness and efficiency of schistosomiasis surveillance could be improved by conducting rapid risk assessment at the beginning of transmission season. WHAT ARE THE IMPLICATIONS FOR PUBLIC HEALTH PRACTICE?: Rapid risk assessment is essential in early detection and the active monitoring of indicators of the transmission risks of schistosomiasis in endemic areas. This could work synergistically with surveillance system to minimize infections and prevent rebounds of endemic schistosomiasis outbreaks.

COVID-19 Super Spreading Event Amongst Elderly Individuals - Jilin Province, China, January 2021.

SUMMARY: What is already known on this topic? Clusters of COVID-19 cases often happened in small settings (e.g., families, offices, school, or workplaces) that facilitate person-to-person virus transmission, especially from a common exposure. What is added by this report? On January 10 and 11, 2021, an individual gave three product promotional lectures in Tonghua City, Jilin Province, that ultimately led to a 74-case cluster of COVID-19. Our investigation determined the outbreak to be an import-related COVID-19 superspreading cluster event in which elderly, retired people were exposed to the infected individual during his promotional lectures, which were delivered in a confined space and lasted several hours. What are the implications for public health practice? Routine activities, such as attending a lecture in a classroom, can provide an environment conducive to COVID-19 superspreading events because respiratory viruses can spread easily and widely. We suggest local government to strengthen infection control management, reduce unnecessary indoor large gathering activities, and promote wearing of masks, especially during wintertime in the north of China. Health education for elderly people should promote use of effective personal protection and emphasize the importance of wearing masks.

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.

Corrections to: Molluscicidal effectiveness of Luo-Wei, a novel plant-derived molluscicide, against Oncomelania hupensis, Biomphalaria alexandrina and Bulinus truncatus.

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Molluscicidal effectiveness of Luo-Wei, a novel plant-derived molluscicide, against Oncomelania hupensis, Biomphalaria alexandrina and Bulinus truncatus.

BACKGROUND: Control of snail intermediate hosts has been proved to be a fast and efficient approach for interrupting the transmission of schistosomiasis. Some plant extracts have shown obvious molluscicidal activity, and a new compound Luo-Wei, also named tea-seed distilled saponin (TDS), was developed based on the saponins extracted from Camellia oleifera seeds. We aimed to test the molluscicidal activity of 4% TDS against the intermediate host snails in China and Egypt, and evaluate its environmental safety to non-target organisms. METHODS: In the laboratory, Oncomelania hupensis, Biomphalaria alexandrina and Bulinus truncatus were exposed to 4% TDS, and the median lethal concentration (LC50) was estimated at 24, 48 and 72 h. In the field, snail mortalities were assessed 1, 2, 3 and 7 d post-immersion with 2.5 g/m3 4% TDS and 1, 3, 7 and 15 d post-spraying with 5 g/m2 4% TDS. In addition, the acute toxicity of 4% TDS to Japanese quail (Coturnix japonica), zebrafish (Brachydanio rerio) and freshwater shrimp (Macrobrachium nipponense) was assessed by estimations of LC50 or median lethal dose (LD50). RESULTS: In the laboratory, the LC50 values of 4% TDS for O. hupensis were 0.701, 0.371 and 0.33 mg/L at 24, 48 and 72 h, respectively, and 4% TDS showed a 1.975 mg/L [corrected] 24 h LC50 against B. alexandrina, and a 1.396 mg/L 24 h LC50 against B. truncatus. Across all study regions, the pooled mortalities of O. hupensis were 72, 86, 94 and 98% at 1, 2, 3 and 7 d, following field immersion of 4% TDS at a dose of 2.5 g/m3, and were 69, 77, 85 and 88% at 1, 3, 7 and 15 d, following field spraying at 5 g/m2, respectively. 4% TDS had moderate toxicity to Japanese quail (7 d LD50 > 60 mg/kg) and to shrimp (96 h LC50 = 6.28 mg/L; 95% CI: 3.53-11.2 mg/L), whereas its toxicity to zebrafish was high (96 h LC50 = 0.15 mg/L; 95% CI: 0.14-0.17 mg/L). CONCLUSIONS: 4% TDS is active against O. hupensis, B. alexandrina and B. truncatus under laboratory and field conditions, and it may be a candidate molluscicide of plant origin.

Eco-social determinants of Schistosoma japonicum infection supported by multi-level modelling in Eryuan county, People's Republic of China.

Schistosomiasis remains of considerable public health concern in many tropical and subtropical regions of the world, including the People's Republic of China (P.R. China). The effectiveness of schistosomiasis control interventions are, among other factors, governed by the social-ecological context. However, eco-social determinants of schistosomiasis are poorly understood, particularly at the household or village levels. In the current study, residents in 26 villages of Eryuan county, Yunnan province, P.R. China, were screened for Schistosoma japonicum infection with a serological assay that was followed by stool examination for sero-positive individuals. Bayesian multilevel models with spatial random effects were employed to profile the S. japonicum infection risk based on known transmission sites of S. japonicum that are scattered across individual land parcels in this part of the country. The key risk factors identified with this approach were the absence of a sanitary stall house for livestock and presence of living and infected intermediate host snails in close proximity. We conclude that a spatially explicit Bayesian multilevel approach can deepen our understanding of eco-social determinants that govern schistosomiasis transmission at a small geographical scale.

[Academic influence of institutes in field of schistosomiasis control and research in China].

OBJECTIVE: To assess the academic influence of schistosomiasis control and research institutions in China. METHODS: The papers (including original articles and reviews) pertaining to schistosomiasis in Science Citation Index Expanded (SCIE) of Web of Science (WOS) during the period from 2002 to 2012 were searched. The number of published papers, h index and citation frequencies of the papers of Chinese institutes and authors were analyzed by a bibliometric method, and the academic influences of the institutes and authors were assessed according to the number of published papers and h index. In addition, the scientific knowledge network map was plotted by using the CiteSpace II software to analyze the inter-institution academic collaboration network. RESULTS: From 2002 to 2012, totally 610 papers pertaining to schistosomiasis were published by Chinese scholars, accounted for 16.7% of the published papers in global, and the quantity increased year by year. The number of published papers and h index of the National Institute of Parasitic Diseases (NIPD), China Center for Disease Control and Prevention (China CDC) were 114 and 27, respectively, both of which were ranked at the first position among all the Chinese institutes, and in the academic collaboration network, the NIPD played a central and dominate part. Xiao-Nong Zhou with the h index of 17 became the outstanding academic leader in the research field of schistosomiasis control. CONCLUSIONS: Both number of published papers in SCIE and h index of the Chinese institutes for schistosomiasis control are far inferior to the leading institutions in the world. It suggests that when strengthening the research and control of schistosomiasis, we should pay an attention to the output and sharing of the control experience and achievements.

[Assessment on the effect of joint effort for schistosomiasis control in Hubei Province].

OBJECTIVE: To analyze the progress of implementation of integrated strategy with emphasis on the control of infectious sources and effectiveness for joint-project of schistosomiasis control in Hubei province. METHODS: Data on the endemic status and implementation of each integrated intervention in 6 collaborated counties including Gongan, Hanchuan, Honghu, Jiangling, Xiantao and Yangxin during 2009-2013 were collected and analyzed. 18 administrative villages with a history of endemic schistosomisis from 6 counties were selected for field survey. Individuals aged 6-65 years received screening test by IHA, and feces of antibody positive inhabitants were collected and tested by miracidia hatching technique. Hatching technique was conducted to determine the infection rate of schistosomiasis in cattle if there was any cattle existed. RESULTS: Various interventions were conducted with adaption to the local situation by the Departments of Agriculture, Water Conservancy, Forestry, and Health. The total number of cattle decreased from 75 388 at the beginning of 2009 to 1 805 at the end of 2013 in 6 counties with a reduction rate of 97.5%, while the prevalence in cattle reduced to 0-0.3% in 2013. Snail-infested areas were stable but areas with infected snails decreased significantly, and no infected snails were found in 2012-2013. Meanwhile, the infection rate of human beings on county level were less than 1%. No infected snails and cattle were found in 18 selected villages and the prevalence in inhabitants was in the range of 0-0.8%. CONCLUSION: Cooperation between provincial government and the Ministries of Health and Agruiculture accelerates the process to reach the criteria of transmission control of schistosomiasis in Hubei Province. However, sustainable effort in needed as the current endemic situation of schistosomiasis is stillunstable.

[Assessing the correlation between international collaboration and academic influence in parasitic diseases: a case study of National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention].

OBJECTIVE: To investigate the activity of scientific research and international collaboration in National Institute of Parasitic Diseases (NIPD), Chinese Center for Disease Control and Prevention (China CDC) from 2002 to 2012, and assess the relationship between international collaboration and academic influence at an individual level. METHODS: Non-bibliometric indicators including number and structure of scientific research personnel, number of projects and funds, visiting frequency, etc, were used to assess the activity of scientific research and international collaboration, and bibliometric indicators including publications and h index, were employed to estimate the academic influence of senior professionals in NIPD, China CDC. The relationship between the international collaboration and international academic influence in the control and research of parasitic diseases was evaluated by using analysis of covariance and generalized linear models. RESULTS: There was an increase tendency of the number of projects, funds and visiting frequency in NIPD, China CDC since the foundation of the institute in 2002, notably after 2011. The h2 index of NIPD, China was 7. Analysis of covariance and generalized linear model analysis revealed that the number of international partners (F = 81.75, P < 0.0001) , number of international projects (F = 22.81, P < 0.0001) , number of national projects (F = 7.30, P = 0.0110), and academic degree (F = 3.80, P = 0.0330) contributed greatly to individual academic influence, while visiting frequency, professional title and length of service had no significant association with h index. CONCLUSION: Elevation of international collaboration projects and development of long-term, stable international partnership may enhance the institutional and individual international academic influence in the field of parasitic diseases.

[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 rapid assessment system of environment with high transmission risk of schistosomiasis in marshland and lake regions II establishment and application of measures for field survey].

OBJECTIVE: To establish the measures of schistosomiasis field survey and evaluate the efficacy of their application according to the content of indexes of rapid assessment system to high transmission risks in schistosomiasis endemic areas of lake regions. METHODS: In 2012, based on the analysis of Oncomelania hupensis snail situation, and schistosomiasis epidemic data of human and cattle from 2008-2010, 60 villages from Hunan, Hubei, Jiangxi and Anhui provinces were selected and investigated, and the content of the investigation included the field feces, snail status, and epidemic situation of human and cattle. The systemic sampling was applied for snail investigation; the feces collected from snail investigation field were examined by the hatching test (3 bottles for 1 sample). A cluster random sampling was carried out with more than 300 people in each village. By using the hatching test (3 bottles for 1 sample) , the human stool examination was carried out for the identification of the infected persons who were positive in the immunity test screening. The hatching test was applied for cattle of all the villages (3 bottles for 1 sample). RESULTS: A total of 65 field feces spots were surveyed in 60 villages, field feces were found in 78.46% (51/65) of spots, and the positive rate of field feces was 1.07% (9/842). There were 73.33% (44,160)of villages with cattle, and the largest amount cattle with 329 was found in Wufeng Village, Jiangxi Province. The cattle infection rate was 1.5 1% (4,913,242) in 3242 investigated cattle. The highest cattle infection rate was 4% in Tongxin Village, Jiangxi Province. The population of 47 099 was surveyed, the infection rate was 0.77% (364/47 099), and the highest was 4.37% in Xumuchang Village, Hunan Province. The infection rate was 0 in 43.33% (26/60) of villages. No acute schistosomiasis cases were reported in all the villages in 2011 and 2012. Totally, 77 snail spots in 60 villages were investigated, and 51 spots were marshland and 26 spots were ditches. The schistosome-infected snails were detected in 5.88% (3/51 )of the marshland spots and the living snails were found in 80.39%(41/51) of the spots. The highest density of living snails was 3.20/0.1 m2 in Xumuchang Village, Hunan Province. The average density of infected snails was 0.00045/0.1 m2 (4/8942). The infected snail spots were distributed in Liujiadi Village and Liuhe Village of Hubei Province, and Jiangkou Village of Anhui Province. No infected snails were detected in 26 ditches spots. The living snails were detected in 53.85% (14/26) of the ditches spots. The highest average density of living snails was 3.76/0.1 m2 in Huakou Village, Hubei Province. CONCLUSIONS: The measures of field survey for rapid assessment system of high transmission risks in schistosomiasis endemic areas of lake regions are established and applied with scientific, impersonal and rapid characteristics.

[Field evaluation of a novel plant molluscicide "Luo-wei" against Oncomelania hupensis snails II molluscicidal effect in the field of lake areas in Hanchuan City, Hubei Province].

OBJECTIVE: To evaluate the effect of a novel plant molluscicide "Luo-wei" (Tea-seed distilled saponins, TDS) against Oncomelania hupensis in the field of lake areas in Hanchuan City, Hubei Province. METHODS: Immersing experiment and spraying experiment were carried out in 5 ditches and a beach land respectively in Hanchuan City, Hubei Province to compare the molluscicidal effects among 4% TDS, 50% wettable powder of niclosamide ethanolamine salt (WPN), and 26% suspension concentrate of metaldehyde and niclosamide (MNSC) by different dosages and time. The chi2 test or Fish's exact test was used to examine the differences of snail death rates among them. RESULTS: After 72 h of immersing experiment, the snail death rates in the 2.5 g/m3 TDS group, 3.0 g/m3 TDS group, 2.0 g/m3 WPN group and 2.0 g/m3 MNSC group were 99.33%, 100%, 100%, and 100%, respectively, and there was no significant difference among them (P > 0.05). By the end of 15 d after the spraying experiments, the snail death rates were 91.86% in the 2.0 g/m2 MNSC group, 90.26% in the 5.0 g/m2 TDS group, 87.45% in the 2 g/m2 WPN group, and 86.10% in the 3 g/m2 TDS group. The differences between the 5.0 g/m2 TDS group and 2.0 g/m2 MNSC group, as well as the 3.0 g/m2 TDS group and the 2.0 g/m2 WPN group had no statistical significance (both P > 0.05). CONCLUSIONS: The molluscicidal effect of TDS is similar to that of WPN or MNSC. The recommended dosage of TDS is 2.5 g/m3 for immersing or 5 g/ m2 for spraying in the field.

[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.

[Effect of a novel plant molluscicide "Luo-wei" against Oncomelania hupensis in plateau mountain areas].

OBJECTIVE: To evaluate the effect of a novel plant molluscicide, 4%"Luo-wei" (Tea-seed distilled saponins, TDS) against Oncomelania hupensis snails in plateau mountain areas in Yunnan Province. METHODS: The immersing and spraying experiments were carried out in the ditches and grassland of Xiaolian Administrative Village in Heqing County, Yunnan Province, to assess the molluscicidal effect of 4% TDS comparing with 50% wettable powder of niclosamide ethanolamine salt (WPN) in different environments and time. RESULTS: After immersion for 24, 48 h and 72 h, the snail death rates were 70.67%, 87.33% and 98.67% in the TDS group, whereas being 77.33%, 96.67% and 100.00% in the WPN group, respectively. The differences of the death rates between the two groups 24 h and 72 h after immersing were not statistically significant ( chi2(24h) =1.73, chi2(72h) = 2.01, both P values > 0.05). Seven days after the immersing experiments, the occurrence rate of frames with living snails and the death rate of snails were 20.00% and 93.03% in the TDS group, while those were 13.33% and 95.76% in the WPN group, and there were no significant differences of the 2 indexes between the 2 groups ( chi(2)(Occurrence rate) = 2.27, chi(2)(Death rate) = 0.94, all P values > 0.05). After spraying for 1, 3, 7 d and 15 d, in both groups, the occurrence rates of frames with living snails and the average densities of living snails gradually declined, while the death rates of snails gradually increased with the extension of time. There were no statistically significant differences of the above 3 indexes between the 2 groups (all P values > 0.05). Fifteen days after the spraying experiment, the occurrence rate of frames with living snails and the adjusted death rate of snails were 15.00% and 87.39% in the TDS group and those were 16.67% and 89.32% in the WPN group, respectively. CONCLUSION: The molluscicidal effect of TDS is satisfying in plateau mountain areas, and the molluscicide is worthy of further extension and application.

[Field evaluation of a novel plant molluscicide "Luo-wei" against Oncomelania hupensis IV molluscicidal effect in field of river beach in Dongzhi County, Anhui Province].

OBJECTIVE: To evaluate the field effect of the plant molluscicide "Luo-wei" (tea-seed distilled saponins, TDS) against the snail Oncomelania hupensis in the river beach in Anhui Province. METHODS: The immersing and spraying experiments were carried out in the river beach in Dongzhi County, Anhui Province, to assess the molluscicidal effect of 4% TDS comparing with 50% wettable powder of niclosamide ethanolamine salt (WPN). The chi(2) test or Fish's exact test was used to examine the differences between or among the molluscicidal effects by different environments, molluscicides, application methods, or days after the intervention. Meanwhile, the cost-effectiveness of the two molluscicides was analyzed. RESULTS: After 1, 2 , 3 d and 7 d of the immersion, the snail death rates in both TDS group and WPN group increased gradually, the snail death rates in the two groups after immersing for 7 d were 94.62% and 99.24%, respectively, and there was no significant difference between them ( chi(2) = 3.30, P > 0.05). After 1 , 3 , 7 d and 15 d of spraying, the snail death rates were 70.82%, 79.75%, 85.11% and 91.65% in the TDS group, and 77.71%, 84.27%, 91.90% and 95.58% in the WPN group, respectively, and the differences among the snail death rates of the two groups at each time point were statistically significant (all P values < 0.05). The costs of spraying were 316.71 yuan per 100 m2 for TDS and 309.71 for WPN. CONCLUSIONS: The molluscicidal effect of TDS has reached the requirements of national standard on nature source pesticides in the river beach of the middle and lower reaches of the Yangtze River. It is necessary to further evaluate its cost-effectiveness in large-scale field experiments in the future.

Soil-transmitted helminth reinfection after drug treatment: a systematic review and meta-analysis.

BACKGROUND: Soil-transmitted helminth (STH) infections (i.e., Ascaris lumbricoides, hookworm, and Trichuris trichiura) affect more than a billion people. Preventive chemotherapy (i.e., repeated administration of anthelmintic drugs to at-risk populations), is the mainstay of control. This strategy, however, does not prevent reinfection. We performed a systematic review and meta-analysis to assess patterns and dynamics of STH reinfection after drug treatment. METHODOLOGY: We systematically searched PubMed, ISI Web of Science, EMBASE, Cochrane Database of Systematic Reviews, China National Knowledge Infrastructure, WanFang Database, Chinese Scientific Journal Database, and Google Scholar. Information on study year, country, sample size, age of participants, diagnostic method, drug administration strategy, prevalence and intensity of infection pre- and posttreatment, cure and egg reduction rate, evaluation period posttreatment, and adherence was extracted. Pooled risk ratios from random-effects models were used to assess the risk of STH reinfection after treatment. Our protocol is available on PROSPERO, registration number: CRD42011001678. PRINCIPAL FINDINGS: From 154 studies identified, 51 were included and 24 provided STH infection rates pre- and posttreatment, whereas 42 reported determinants of predisposition to reinfection. At 3, 6, and 12 months posttreatment, A. lumbricoides prevalence reached 26% (95% confidence interval (CI): 16-43%), 68% (95% CI: 60-76%) and 94% (95% CI: 88-100%) of pretreatment levels, respectively. For T. trichiura, respective reinfection prevalence were 36% (95% CI: 28-47%), 67% (95% CI: 42-100%), and 82% (95% CI: 62-100%), and for hookworm, 30% (95% CI: 26-34%), 55% (95% CI: 34-87%), and 57% (95% CI: 49-67%). Prevalence and intensity of reinfection were positively correlated with pretreatment infection status. CONCLUSION: STH reinfections occur rapidly after treatment, particularly for A. lumbricoides and T. trichiura. Hence, there is a need for frequent anthelmintic drug administrations to maximize the benefit of preventive chemotherapy. Integrated control approaches emphasizing health education and environmental sanitation are needed to interrupt transmission of STH.

[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.

[Establishment and application of spatio-temporal model of schistosomiasis japonica in a county in marshland region].

OBJECTIVE: To develop a spatio-temporal model of schistosomiasis japonica based on Bayesian model, and to analyze the spatio-temporal pattern of schistosomiasis, as well as to evaluate the impact of environment changes on schistosomiasis endemic. METHODS: Different Bayesian models were established by employing the data of the periodical surveillance on schistosomiasis during 1996-2005 period by taking into account of the uncertainty in sensitivity and specificity of diagnostic test, then the best fitness model was selected to analyze the spatio-temporal pattern of schistosomiasis and evaluate the impact of environment changes on schistosomiasis. RESULTS: The model with space-time interaction was a better fitting model. No significant temporal correlation was found in human infection rate of Schistosoma japonicum, and the difference of spatial structure between human infection rates of each year was significant. The prediction map of S. japonicum infection showed the changes of infection in the south areas of the Yuan River were not significant, while the prevalence increased significantly in the north areas of the river, which indicated that the impact of the implementation of project on partial abandon areas for water storing on prevalence of S. japonicum was stronger than that of the project on completed abandon areas for water storing. CONCLUSIONS: It is feasible to develop the spatio-temporal model of schistosomiasis japonica based on Bayesian model, and this inetegrated Bayesian model approach may become a powerful and statistically robust tool for estimating and evaluating the control strategy.