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Objective To understand the current status of capacity building in schistosomiasis control institutes in schistosomiasis-endemic provinces (municipality, autonomous region) of China. Methods The responsibilities and construction requirements of various schistosomiasis control institutions were surveyed by expert discussions, and field interviews and visits during the period between May and June, 2023, and the questionnaire for capacity maintenance and consolidation in schistosomiasis control institutions was designed. An online questionnaire survey was conducted in county-, municipal-, and provincial-level institutions that undertook schistosomiasis control and surveillance activities through the Wenjuanxing program. The distribution of schistosomiasis control institutions, the status of institutions, departments and staff undertaking schistosomiasis control activities and the translation of scientific researches on schistosomiasis control in China were analyzed. The laboratories accredited by China National Accreditation Service for Conformity Assessment (CNAS) were considered to be capable for testing associated with schistosomiasis control, and the testing capability of schistosomiasis control institutions was analyzed. Results A total of 486 valid questionnaires were recovered from 486 schistosomiasis control institutions in 12 endemic provinces (municipality, autonomous region) of China, including 12 provincial-level institutions (2.5%), 77 municipal-level institutions (15.8%) and 397 county-level institutions (81.7%). Of all schistosomiasis control institutions, 376 (77.4%) were centers for disease control and prevention or public health centers, 102 (21.0%) were institutions for schistosomiasis, endemic disease and parasitic disease control, and 8 (1.6%) were hospitals, healthcare centers or others. There were 37 713 active employees in the 486 schistosomiasis control institutions, including 5 675 employees related to schistosomiasis control, and the proportions of employees associated with schistosomiasis control among all active employees were 5.9% (231/3 897), 5.5% (566/10 134), and 20.6% (4 878/23 682) in provincial-, municipal-, and county-level institutions, respectively. There were 3 826 full-time employees working in schistosomiasis control activities, with 30.5% (1 166/3 826), 34.6% (1 324) and 34.9% (1 336/3 826) at ages of 40 years and below, 41 to 50 years and over 50 years, and there were 1 571 (41.0%) full-time schistosomiasis control employees with duration of schistosomiasis control activities for over 25 years, and 1 358 (35.5%) employees with junior professional titles and 1 290 with intermediate professional titles (35.5%), while 712 (18.6%) full-time employees working in schistosomiasis control activities had no professional titles. The three core schistosomiasis control activities included snail control (26.3%, 374/1 420), epidemics surveillance and management (25.4%, 361/1 420) and health education (18.8%, 267/1 420) in schistosomiasis control institutions. The Kato-Katz method, miracidium hatching test with nylon gauzes, and indirect haemagglutination assay (IHA) were the most commonly used techniques for detection of schistosomiasis, and there were less than 50% laboratories that had capabilities or experimental conditions for performing enzyme-linked immunosorbent assay (ELISA), dipstick dye immunoassay (DDIA), dot immunogold filtration assay (DIG-FA), loop-mediated isothermal amplification (LAMP) and polymerase chain reaction (PCR) assays. During the period from 2018 to 2022, schistosomiasis control institutions had undertaken a total of 211 research projects for schistosomiasis control, with a total funding of 18.596 million RMB, published 619 articles, participated in formulation of 13 schistosomiasis control-related criteria, and applied for 113 schistosomiasis control-related patents, including 101 that were granted, and commercialized 4 scientific research outcomes. Conclusions The proportion of independent specialized schistosomiasis control institutions is low in schistosomiasis control institutions in China, which suffers from problems of unsatisfactory laboratory testing capabilities, aging of staff and a high proportion of low-level professional titles. More investment into and intensified schistosomiasis control activities and improved capability building and talent cultivation in schistosomiasis control institutions are recommended to provide a powerful support for high-quality elimination of schistosomiasis in China.
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Objective To establish a snail control approach for spraying chemicals with drones against Oncomelania hupensis in complex snail habitats in hilly regions, and to evaluate its molluscicidal effect. Methods The protocol for evaluating the activity of spraying chemical molluscicides with drones against O. hupensis snails was formulated based on expert consultation and literature review. In August 2022, a pretest was conducted in a hillside field environment (12 000 m2) north of Dafengji Village, Dacang Township, Weishan County, Yunnan Province, which was assigned into four groups, of no less than 3 000 m2 in each group. In Group A, environmental cleaning was not conducted and 5% niclosamide ethanolamine salt granules were sprayed with drones at a dose of 40 g/m2, and in Group B, environmental cleaning was performed, followed by 5% niclosamide ethanolamine salt granules sprayed with drones at a dose of 40 g/m2, while in Group C, environmental cleaning was not conducted and 5% niclosamide ethanolamine salt granules were sprayed with knapsack sprayers at a dose of 40 g/m2, and in Group D, environmental cleaning was performed, followed by 5% niclosamide ethanolamine salt granules sprayed with knapsack sprayers at a dose of 40 g/m2. Then, each group was equally divided into six sections according to land area, with Section 1 for baseline surveys and sections 2 to 6 for snail surveys after chemical treatment. Snail surveys were conducted prior to chemical treatment and 1, 3, 5, 7 days post-treatment, and the mortality and corrected mortality of snails, density of living snails and costs of molluscicidal treatment were calculated in each group. Results The mortality and corrected mortality of snails were 69.49%, 69.09%, 53.57% and 83.48%, and 68.58%, 68.17%, 52.19% and 82.99% in groups A, B, C and D 14 days post-treatment, and the density of living snails reduced by 58.40%, 63.94%, 68.91% and 83.25% 14 days post-treatment relative to pre-treatment in four groups, respectively. The median concentrations of chemical molluscicides were 37.08, 35.42, 42.50 g/m2 and 56.25 g/m2 in groups A, B, C and D, and the gross costs of chemical treatment were 0.93, 1.50, 0.46 Yuan per m2 and 1.03 Yuan per m2 in groups A, B, C and D, respectively. Conclusions The molluscicidal effect of spraying 5% niclosamide ethanolamine salt granules with drones against O. hupensis snails is superior to manual chemical treatment without environmental cleaning, and chemical treatment with drones and manual chemical treatment show comparable molluscicidal effects following environmental cleaning in hilly regions. The cost of chemical treatment with drones is slightly higher than manual chemical treatment regardless of environmental cleaning. Spraying 5% niclosamide ethanolamine salt granules with drones is recommended in complex settings with difficulty in environmental cleaning to improve the molluscicidal activity and efficiency against O. hupensis snails.
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Objective To analyze the distribution characteristics of emerging and reemerging Oncomelania hupensis snails after the criteria for transmission control of schistosomiasis were achieved in China, so as to provide insights into assessment of schistosomiasis transmission risk and formulation of snail control strategies during the elimination phase. Methods O. hupensis survey data in China from 2015 to 2021 were collected from the National Schistosomiasis Pevention and Control Information Management System, and the distribution characteristics of emerging and reemerging O. hupensis snails were descriptively analyzed. Results Emerging and reemerging O. hupensis snails were identified in China each year from 2015 to 2021, with relatively larger areas with emerging and reemerging O. hupensis snail habitats in 2016 and 2021, and relatively higher numbers of counties (districts) where emerging and reemerging O. hupensis snails were detected in 2016 and 2021. A total of 4 586.30 hm2 of emerging O. hupensis snail habitats were found in 10 schistosomiasis-endemic provinces of China (except Fujian and Yunnan Provinces) from 2015 to 2021, with 96.80% in Anhui, Hunan and Hubei provinces, where marshland and lake endemic foci were predominant. A total of 21 023.90 hm2 of reemerging O. hupensis snail habitats were found in 12 schistosomiasis-endemic provinces of China from 2015 to 2021, with 97.67% in six provinces of Hubei, Sichuan, Jiangxi, Jiangsu, Yunnan and Anhui, where marshland and lake and hilly endemic regions were predominant. Emerging snail habitats were found in 15.08% of all schistosomiasisendemic counties (districts) in China from 2015 to 2021, and 78.75% of all emerging snail habitats were identified in 11 schistosomiasis-endemic counties (districts), with the largest area of emerging snail habitats found in Lixian County, Hunan Province (645.00 hm2). Reemerging snail habitats were found in 47.67% of all schistosomiasis-endemic counties (districts) in China from 2015 to 2021, and 43.29% of all reemerging snail habitats were identified in 11 schistosomiasis-endemic counties (districts), with the largest area of reemerging snail habitats found in Weishan Li and Hui Autonomous County of Hunan Province (1 579.70 hm2). Conclusions Emerging and reemerging O. hupensis snails were identified in China each year from 2015 to 2021, with much larger areas of reemerging snail habitats than emerging snail habitats, and larger numbers of schistosomiasis-endemic provinces and counties (districts) with reemerging snails were found that those of provinces and counties (districts) with emerging snails. Specific snail control interventions are required tailored to the causes of emerging and reemerging snail habitats. Both emergence and reemergence of O. hupensis snails should be paid attention to in marshland and lake endemic areas, and Guangxi Zhuang Autonomous Region, Shanghai Municipality and Zhejiang Province where schistosomiasis had been eliminated, and reemergence of O. hupensis snails should be given a high priority in hilly areas. In addition, monitoring of O. hupensis snails should be reinforced in snail-free areas after flooding.
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This report presented the endemic status of schistosomiasis and analyzed the data collected from the national schistosomiasis prevention and control system and national schistosomiasis surveillance program in the People’s Republic of China in 2022. Among the 12 provinces (municipality and autonomous region) endemic for schistosomiasis, Shanghai Municipality, Zhejiang Province, Fujian Province, Guangdong Province and Guangxi Zhuang Autonomous Region continued to maintain the achievements of schistosomiasis elimination, and Sichuan and Jiangsu provinces maintained the criteria of transmission interruption, while Yunnan, Hubei, Anhui, Jiangxi and Hunan provinces maintained the criteria of transmission control by the end of 2022. A total of 452 counties (cites, districts) were found to be endemic for schistosomiasis in China in 2022, with 27 434 endemic villages covering 73 424 400 people at risk of infections. Among the 452 endemic counties (cities, districts), 75.89% (343/452), 23.45% (106/452) and 0.66% (3/452) achieved the criteria of elimination, transmission interruption and transmission control of schistosomiasis, respectively. In 2022, 4 317 356 individuals received serological tests for schistosomiasis, and 62 228 were sero-positive. A total of 208 646 individuals received stool examinations for schistosomiasis, with one positive and another two cases positive for urine microscopy, and these three 3 cases were imported schistosomiasis patients from Africa. There were 28 565 cases with advanced schistosomiasis documented in China by the end of 2022. Oncomelania hupensis snail survey was performed in 18 891 endemic villages in China in 2022 and O. hupensis snails were found in 6 917 villages (36.62% of all surveyed villages), with 8 villages identified with emerging snail habitats. Snail survey was performed at an area of 655 703.01 hm2 and 183 888.60 hm2 snail habitats were found, including 110.58 hm2 emerging snail habitats and 844.35 hm2 re-emerging snail habitats. There were 477 200 bovines raised in the schistosomiasis endemic areas of China in 2022, and 113 946 bovines received serological examinations for schistosomiasis, with 204 sero-positives detected. Among the 131 715 bovines received stool examinations, no positives were identified. In 2022, there were 19 726 schistosomiasis patients receiving praziquantel chemotherapy, and expanded chemotherapy was performed in 714 465 person-time for humans and 234 737 herd-time for bovines in China. In 2022, snail control with chemical treatment was performed at an area of 119 134.07 hm2, and the actual area of chemical treatment was 65 825.27 hm2, while environmental improvements were performed at an area of 1 163.96 hm2. Data from the national schistosomiasis surveillance program of China showed that the mean prevalence of Schistosoma japonicum infections was both zero in humans and bovines in 2022, and no S. japonicum infection was detected in O. hupensis snails. These data demonstrated that the endemic status of schistosomiasis continued to decline in China in 2022, with 3 confirmed schistosomiasis patients that had a foreign nationality and all imported from Africa, and the areas of snail habitats remained high. Further improvements in the construction of the schistosomaisis surveillance and forecast system, and reinforcement of O. hupensis survey and control are required to prevent the re-emerging schistosomiasis.