Dataset Information

Schistosomiasis in the People's Republic of China - down but not out.

ABSTRACT: Schistosomiasis has been subjected to extensive control efforts in the People's Republic of China (China) which aims to eliminate the disease by 2030. We describe baseline results of a longitudinal cohort study undertaken in the Dongting and Poyang lakes areas of central China designed to determine the prevalence of Schistosoma japonicum in humans, animals (goats and bovines) and Oncomelania snails utilizing molecular diagnostics procedures. Data from the Chinese National Schistosomiasis Control Programme (CNSCP) were compared with the molecular results obtained.Sixteen villages from Hunan and Jiangxi provinces were surveyed; animals were only found in Hunan. The prevalence of schistosomiasis in humans was 1.8% in Jiangxi and 8.0% in Hunan determined by real-time polymerase chain reaction (PCR), while 18.3% of animals were positive by digital droplet PCR. The CNSCP data indicated that all villages harboured S. japonicum-infected individuals, detected serologically by indirect haemagglutination assay (IHA), but very few, if any, of these were subsequently positive by Kato-Katz (KK).Based on the outcome of the IHA and KK results, the CNSCP incorporates targeted human praziquantel chemotherapy but this approach can miss some infections as evidenced by the results reported here. Sensitive molecular diagnostics can play a key role in the elimination of schistosomiasis in China and inform control measures allowing for a more systematic approach to treatment.

SUBMITTER: Gordon CA

PROVIDER: S-EPMC11010531 | biostudies-literature | 2022 Feb

REPOSITORIES: biostudies-literature

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Schistosomiasis in the People's Republic of China - down but not out.

Gordon Catherine A CA Williams Gail M GM Gray Darren J DJ Clements Archie C A ACA Zhou Xiao-Nong XN Li Yuesheng Y Utzinger Jürg J Kurscheid Johanna J Forsyth Simon S Addis Alene Kefyalew K Zhou Jie J Li Zhaojun Z Li Guangpin G Lin Dandan D Lou Zhihong Z Li Shengming S Ge Jun J Xu Jing J Yu Xinling X Hu Fei F Xie Shuying S Chen Jie J Shi Tao T Li Chong C Zheng Huajun H McManus Donald P DP

Parasitology 20211103 2

Schistosomiasis has been subjected to extensive control efforts in the People's Republic of China (China) which aims to eliminate the disease by 2030. We describe baseline results of a longitudinal cohort study undertaken in the Dongting and Poyang lakes areas of central China designed to determine the prevalence of Schistosoma japonicum in humans, animals (goats and bovines) and Oncomelania snails utilizing molecular diagnostics procedures. Data from the Chinese National Schistosomiasis Control ...[more]

PMID: 35234601

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Project description:BackgroundAsian schistosomiasis is projected to be eliminated by 2030 according to World Health Organization road map for neglected tropical diseases 2021-2030. Snail control is an important measure but has not yet been systematically evaluated at a country scale. Here, we report the findings from a nationwide survey to demonstrate the dynamics of Oncomelania and its potential role in transmission interruption of schistisomiasis in the People's Republic of China (P.R. China).MethodsBetween March 2016 and December 2017, we conducted a nationwide census on Oncomelania snail habitats in P.R. China. All historically recorded snail habitats were identified and reviewed. Information on habitat attributes, including the infestation of snails, was collected. The shape of habitats was determined using global positioning system and geographical information system technologies. The relationship between snail control and schistosomiasis elimination was established in 378 endemic counties. The comparison of accumulated snail-infested range (ASR) and the median ratio of eliminated ASR between the transmission-interrupted and endemic counties was tested by a non-parametric test (Mann-Whitney) with a significance level of 0.05.ResultsOverall, 15,377.7 million m2 of potential snail habitats with a total of 356,550 snail habitats were identified in P.R. China. The ASR amounted to 86.0% of the total area. Most of the ASR (94.9%) and habitats (68.5%) were distributed in the middle and lower reaches of the Yangtze River. Snail habitats were found up to an altitude of 2859 m above the mean sea level. By 2017, 85.1% of habitats (73.0% of the ASR) had been eliminated with almost half of them eliminated between 1965 and 1982. The elimination of snail habitats promoted transmission interruption of schistosomiasis, but showed variable patterns in different landscapes. The ratio of eliminated ASR was 99.6 and 91.4% in water network and hilly areas, respectively, while it was only 64.8% in marshland areas, particularly in Hunan and Jiangxi where the two largest freshwater lakes of P.R. China are located. Marshland habitats were seen as the most difficult for transmission interruption, which calls for additional control measures in these settings.ConclusionsOur results support recent recommendations by the World Health Organization to implement snail control and demonstrate that schistosomiasis elimination can be achieved. The nationwide, high-resolution map of Oncomelania snail habitats in P.R. China will support further efforts to eliminate schistosomiasis.

Project description:BackgroundSnail control is an important component in the national schistosomiasis control programme in China, by application of chemical molluscicides, forestry projects, agriculture projects and water conservancy projects in recent decades. However, there are still wide areas of snail inhabited in China which remains a great challenge to achieve the goal of schistosomiasis elimination by 2025. Therefore, a SWOT (strengths, weaknesses, opportunities and threats) analysis on snail control measures is required for precision schistosomiasis control.MethodsThe SWOT approach, which is a well-known structured analysis tool, was used to identify and evaluate the specific characteristics of four types of snail control measures in China, including chemical mollusciciding, forestry, agriculture, and water conservancy projects. The analysis were carried out based on the information collection from literature review, of research papers, books, annual report database of national schistosomiasis control programme in China, reports from the academic forums, and so on.ResultsFor chemical mollusciciding, application strategy needs to focus on specific local settings, such as stage of schistosomiasis control, environmental factors, and limitations from external policies and internal deficiencies. Regarding forestry projects, the optimal strategies are to cooperate with other national forestry programmes to share the investment costs and pay attention on wetland protection. In agriculture projects, it is necessary to develop related cash crop industries and combine with national farmland consolidation projects simultaneously to increase the total economic benefits. Concerning water conservancy projects, the main purpose is to control snail migration from snail area to snail-free areas nationwide.ConclusionsIntegrated strategies for various measures application and a top-level designed cooperation mechanism will be the necessary to eliminate snail and schistosomiasis in China.

Project description:BackgroundThe People's Republic of China (P. R. China) has made significant progress on schistosomiasis control. Among the 12 provincial-level administrative divisions (PLADs) with schistosomiasis endemic in P. R. China, Guangdong, Shanghai, Fujian, Guangxi and Zhejiang PLADs (following as five PLADs) had successively eliminated schistosomiasis during 1985-1995. However, consolidation of the schistosomiasis elimination in these five PLADs remains challenging. In the current study, we sought to understand the epidemic situation in these post-elimination areas and their surveillance capabilities on schistosomiasis.MethodsAnnual data reflecting the interventions and surveillance on human beings, cattle and snails based on county level from 2005 to 2016 were collected through the national schistosomiasis reporting system and the data were analyzed to understand the epidemic status of schistosomiasis in the five PLADs. A standardized score sheet was designed to assess the surveillance capacity for schistosomiasis of selected disease control agencies in five PLADs and ten counties. Assessment on surveillance capacity including schistosomiasis diagnostic skills, identification of snails' living and infection status and knowledge about schistosomiasis and its control were made. Descriptive analysis was used to analyze the epidemic status and evaluation results on surveillance capacities.ResultsThe assessments showed that no local cases in humans and cattle or infected snail were found in these five PLADs since 2005. However, from 2005 to 2016, a total of 221 imported cases were detected in Zhejiang, Shanghai and Fujian, and 11.98 hm2 of new snail habitats were found in Zhejiang, Shanghai and Guangxi. In addition, snail infestation reoccurred in 247.55 hm2 of former snail habitats since 2011. For the surveillance capacity assessment, the accuracy rate of IHA and MHT were 100 and 89.3%, respectively. All participants could judge the living status of snails accurately and 98.1% on the infection status of snails. The accuracy rate of the questionnaire survey was 98.0%.ConclusionsElimination of schistosomiasis was consolidated successfully in five PLADs of P. R. China due to effective and strong post-elimination surveillance. Comprehensive consolidation strategies should be focused on the elimination of residual snails and the prevention of imported infection sources to consolidate the achievements of schistosomiasis control.

Project description:Despite significant progress, China faces the challenge of re-emerging schistosomiasis transmission in currently controlled areas due, in part, to the presence of a range of animal reservoirs, notably water buffalo and cattle, which can harbor Schistosoma japonicum infections. Environmental, ecological and social-demographic changes in China, shown to affect the distribution of oncomelanid snails, can also impact future schistosomiasis transmission. In light of their importance in the S. japonicum, lifecycle, vaccination has been proposed as a means to reduce the excretion of egg from cattle and buffalo, thereby interrupting transmission from these reservoir hosts to snails. A DNA-based vaccine (SjCTPI) our team developed showed encouraging efficacy against S. japonicum in Chinese water buffaloes. Here we report the results of a double-blind cluster randomized trial aimed at determining the impact of a combination of the SjCTPI bovine vaccine (given as a prime-boost regimen), human mass chemotherapy and snail control on the transmission of S. japonicum in 12 selected administrative villages around the Dongting Lake in Hunan province. The trial confirmed human praziquantel treatment is an effective intervention at the population level. Further, mollusciciding had an indirect ~50% efficacy in reducing human infection rates. Serology showed that the SjCTPI vaccine produced an effective antibody response in vaccinated bovines, resulting in a negative correlation with bovine egg counts observed at all post-vaccination time points. Despite these encouraging outcomes, the effect of the vaccine in preventing human infection was inconclusive. This was likely due to activities undertaken by the China National Schistosomiasis Control Program, notably the treatment, sacrifice or removal of bovines from trial villages, over which we had no control; as a result, the trial design was compromised, reducing power and contaminating outcome measures. This highlights the difficulties in undertaking field trials of this nature and magnitude, particularly over a long period, and emphasizes the importance of mathematical modeling in predicting the potential impact of control intervention measures. A transmission blocking vaccine targeting bovines for the prevention of S. japonicum with the required protective efficacy would be invaluable in tandem with other preventive intervention measures if the goal of eliminating schistosomiasis from China is to become a reality.

Project description:BackgroundSchistosomiasis japonica is still endemic in the People's Republic of China (P.R. China) in five provinces of lake and marshland regions and in two provinces of mountainous regions. Studies elucidated that individual and community perception, attitudes towards schistosomiasis, and hygiene behaviors were crucial factors for preventing schistosomiasis. This study sought to assess the knowledge of, attitudes towards, and practices (KAP) relating to schistosomiasis in two subtypes of a mountainous region in Eryuan County, Yunnan Province, P.R. China. The study's aim is to make suggestions for establishing more specific and effective control measures for disease transmission and interruption in two subtypes of a mountainous region with low-level infection rates.MethodsA cross-sectional study of 3,000 inhabitants was carried out in the Yongle (plateau basin) and Xinzhuang (plateau canyon) communities of Eryuan County, Yunnan Province in November and December 2011. Stratified cluster random sampling was undertaken using a uniform set of quantitative questionnaires administered by trained assistants. This was further supported with qualitative data from in-depth interviews (IDIs) conducted with ten farmers and ten students. All participants were examined for schistosomiasis using both a serological test (indirect hemagglutination assay [IHA]) and a stool examination (Kato-Katz).ResultsThe total schistosomiasis knowledge rate in Yongle (83.4%) was significantly lower than that in Xinzhuang (95.5%). In both communities, among the respondents aged 15 years or below, more than one third didn't know the name, endemic areas, and animal reservoirs of schistosomiasis. The majority of respondents in Eryuan acquired their schistosomiasis knowledge from doctors, followed by handouts and hearing from others. The infection rate was once the highest in Yongle, but is now the highest in Xinzhuang, where there are more risk factors for schistosomiasis, such as frequently grazing cattle, digging vegetables or cutting grass in the field, as well as raising cattle by free grazing.ConclusionIn short, Eryuan County's overall knowledge rate of schistosomiasis was found to be high. Due to various dominating risk factors, different control strategies should be designed keeping in mind the two different subtypes of endemic areas for schistosomiasis in mountainous regions, namely plateau basins and plateau canyons.

Dataset Information

Schistosomiasis in the People's Republic of China - down but not out.

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Schistosomiasis in the People's Republic of China - down but not out.

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