Schistosomiasis Control In China Research Articles

The National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention: a new administrative structure for schistosomiasis control

Since more than 5 decades, the overall responsibility for the national programme on schistosomiasis control in China resides at the government level, i.e. Ministry of Health. Day-to-day activities are carried out by independent provincial parasitic institutes situated in the endemic areas. Along with the general economic development and the steady progress in the medical sciences, successful developments in control and research of the parasitic diseases in the country were achieved. This necessitated a corresponding reorganization of the administrative structures which has taken place at several levels. In January 2002, the Chinese Centre for Disease Control and Prevention was reorganized and the Institute of Parasitic Diseases in Shanghai became part of this new organization under the name of the National Institute of Parasitic Diseases to better reflect its new role. By assigning all administrative tasks regarding research and control of parasitic diseases under the umbrella of one administrative central laboratory, the new task force for epidemiological surveys and direction of parasitic control programmes is well suited to respond to the daunting challenges of the future. The new institution has only existed for a few years but has already become a well-functioning force with a broad contact net of national and international experts on research and control of parasitic diseases.

Optimal combined approaches of field intervention for schistosomiasis control in China

Before the mid 1980s, the emphasis in schistosomiasis control in China was on transmission control. Thus, the aim was to eliminate the intermediate host snail by environmental management, combined with chemotherapy, water supply and sanitation, and hygiene improvement. During the last 20 years, however, control approaches mainly consisting of large-scale praziquantel-based chemotherapy and health education started to be advocated and also increasingly applied. Here, we review the literature with an emphasis on combined approaches of field interventions that have been implemented for schistosomiasis control in China over the past 50 years. The interventions consist of both pilot studies and large-scale implementation during different historical periods. The feasibility and effectiveness of the various combined approaches are examined and analysed in relation to local economic conditions and the prevailing scientific and technical expertise. Finally, a set of recommendations is put forward for contemporary schistosomiasis control readily adapted to different eco-epidemiological settings in China.

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.

A review of geographic information system and remote sensing with applications to the epidemiology and control of schistosomiasis in China

Geographic information system (GIS) and remote sensing (RS) technologies offer new opportunities for rapid assessment of endemic areas, provision of reliable estimates of populations at risk, prediction of disease distributions in areas that lack baseline data and are difficult to access, and guidance of intervention strategies, so that scarce resources can be allocated in a cost-effective manner. Here, we focus on the epidemiology and control of schistosomiasis in China and review GIS and RS applications to date. These include mapping prevalence and intensity data of Schistosoma japonicum at a large scale, and identifying and predicting suitable habitats for Oncomelania hupensis, the intermediate host snail of S. japonicum, at a small scale. Other prominent applications have been the prediction of infection risk due to ecological transformations, particularly those induced by floods and water resource developments, and the potential impact of climate change. We also discuss the limitations of the previous work, and outline potential new applications of GIS and RS techniques, namely quantitative GIS, WebGIS, and utilization of emerging satellite information, as they hold promise to further enhance infection risk mapping and disease prediction. Finally, we stress current research needs to overcome some of the remaining challenges of GIS and RS applications for schistosomiasis, so that further and sustained progress can be made to control this disease in China and elsewhere.

The role of ‘passive chemotherapy’ plus health education for schistosomiasis control in China during maintenance and consolidation phase

In order to explore the possibility of further optimising schistosomiasis control during the maintenance and consolidation phase in China, two highly endemic villages were selected to compare the strategy of ‘passive chemotherapy’ plus health education to that of mass chemotherapy singly. Emphasis was placed on treatment coverage with praziquantel among individuals infected with Schistosoma japonicum and costs incurred for treating an infected person. The results show that the former strategy was almost as good as the latter producing treatment coverage rates among egg-positives of 96.2–97.1% during 2 years, while corresponding rates of 100% were achieved in the village where mass chemotherapy was employed. Importantly, the cost of the former strategy was only about half that of mass chemotherapy, i.e. 49.0% in the first year and 54.6% in the following. Moreover, ‘passive chemotherapy’ together with health education can conveniently be integrated into the primary health care system making it an attractive strategy for schistosomiasis control during the maintenance and consolidation phase.

Development of antischistosomal drugs in China, with particular consideration to praziquantel and the artemisinins

Remarkable achievements have been made in the control of schistosomiasis in China, with chemotherapy playing a seminal role. From the early 1950s through the early 1980s, Chinese scientists made considerable progress in discovery and development of compounds with antischistosomal properties, including antimonials, non-antimonials and various effective principles stemming from traditional herbs. However, only few compounds entered clinical testing, while others were abandoned mainly due to their toxicity and poor efficacy. The advent of praziquantel in the 1970s changed the landscape of research and development of drugs for treatment and morbidity control of schistosomiasis. The main Chinese contributions to enhance the understanding of the antischistosomal drug praziquantel are reviewed here, including issues of metabolism, antibody-dependency, host immune factors, stage-specific susceptibility and resistance. Over the past 25 years, researchers from China successfully developed artemether and artesunate, two derivatives from the antimalarial artemisinin, as promising drugs against Schistosoma japonicum. Laboratory investigations showed that the artemisinins display their highest activity against the juvenile stages of the parasite. These findings were consistently confirmed in randomised controlled trials; repeated oral administration of artemether or artesunate was safe and efficacious in the prevention of patent S. japonicum infections. The key findings are reviewed here, and emphasis is placed on how it stimulated research outside of China on other human schistosome species.

Prospects for development of a transmission blocking vaccine against Schistosoma japonicum

Despite intensive long-term control programmes, schistosomiasis japonica remains a serious public health problem in China and the Philippines. The termination of mass praziquantel-treatment has seen a dramatic recent rebound in both its prevalence and associated morbidity. Schistosomiasis japonica is a zoonosis but, despite complicating control efforts, this feature provides a practical method for attacking Schistosoma japonicum through development and deployment of a transmission blocking veterinary vaccine. A recently completed bovine drug intervention trial and mathematical modelling of the transmission of S. japonicum underpin the concept that such a vaccine, targeting water buffalo, would have major implications for future integrated schistosomiasis control in China. A major block to success is the low ceiling efficacy achieved with current vaccine molecules. To solve this challenge, an antigen discovery pipeline needs to be established for identification of new vaccine targets that induce greater potency than the current anti-S. japonicum candidate vaccines. Excretory-secretory products and molecules exposed on epithelial surfaces (including receptors) which interact directly with the host immune system warrant especial attention. Extensive schistosome genomics programmes currently underway coupled with new advances in proteomics and microarray technology provide an unparalleled opportunity to identify new molecules exploitable as vaccine targets. These will then need to be produced in quantity and rigorously tested first in the laboratory and then the field. If a transmission blocking veterinary vaccine developed for bovines can be put into practice in combination with other control strategies such as human chemotherapy, elimination of S. japonicum from China may be achievable.

Market reform: a challenge to public health?the case of schistosomiasis control in China

This study examines how the provision of schistosomiasis control has adapted to increased exposure to market forces which has occurred in China over the past decades with the main emphasis on contemporary performance of the services. Financial and service data were collected and analysed from ten schistosomiasis stations in the Hunan province. A document and literature review, key informant interviews, as well as two focus group discussions were conducted to establish their context. The study found that the schistosomiasis control stations had shifted their emphasis from prevention to clinical services and that 62% of the stations' total income now comes from charging for individual clinical services, while 90% of the total costs was related to providing these services. The study found that revenue generation had become the primary motive, and that over-treatment and prescription had become an accepted practice for all the stations. The study concludes that a combination of lax supervision and accountability, and a greater reliance on user-payment and market mechanisms has severely compromised the provision of the public goods elements of the schistosomiasis control programme.

Is equity being sacrificed? Willingness and ability to pay for schistosomiasis control in China.

Decentralization of the health care system in China has led to an increasing need for income generation at all operational levels, both for curative services and for public health programmes. In general, people have accepted the costs of curative services, although the impact of charges on health-seeking behaviour has yet to be assessed. Public health programmes present particular problems in terms of revenue generation, however, because of the less direct impact of these activities on individual health and well-being. In this paper, we report the results of a cross-sectional study of willingness and ability to pay for schistosomiasis control. Questionnaires were administered to household heads of six representative villages in the Dongting Lake Region of Hunan Province, China. A total of 628 valid questionnaires were analyzed. The yearly mean household expenditure on schistosomiasis diagnosis and treatment was RMB 59.50 +/- 146.04 Yuan (US$1 = 8 RMB Yuan), accounting for 0.94% of the total yearly household income. Most household heads (514, 82%) thought schistosomiasis was the greatest health threat in their communities, but only 30.9% of them were willing to pay for screening, diagnosis and treatment of the infection. On the other hand, 72.3% of the respondents were willing to undertake volunteer work for control.

Schistosomiasis control in China

This review on the control of schistosomiasis in China consists of the disease in the past, epidemiology, control programme, control approaches, achievements, problems existed and an appendix: the criteria for control and elimination of schistosomiasis in China.

Financing changes of schistosomiasis control programmes in China 1980-1995: a case study in Songzi county.

To assess the financing changes of schistosomiasis control programmes in China and estimate the impact of these changes on patients' treatment-seeking behaviour and control of schistosomiasis, a survey was conducted in five schistosomiasis-endemic areas of the lake regions, Hubei province, in 1996. This paper reports financing changes and their impact on the incidence and prevalence of schistosomiasis from one of the five areas as a case study. By examining the surveillance and financial data from 1980 to 1995, and through focus group discussions we found that the schistosomiasis control programmes in People's Republic of China have gone through dramatic financing changes from 1980 to 1995, when the transitions of China's social, economic, and political systems happened. The proportions of funding to schistosomiasis control programmes from high level governmental agencies, county budgets, and services revenue changed from 60%, 23%, and 17%, respectively, in 1980-1987 to 0.7%, 22.3%, and 72% in 1995. The percentages of expenditure of schistosomiasis control activities, salaries and bonuses, and other activities unrelated to schistosomiasis control, were 53.5%, 14.4, and 17.2% in 1980. These percentages changed to 7.7%, 33.3%, and 53.3%, respectively, in 1995. The preponderant role of the state in organizing, financing, and delivery of the services was replaced with the new system which is more influenced by the market economy. The incidence and the prevalence of schistosomiasis in the study area have increased year by year from 1980 to 1990, although there has been a tendency to decrease after 1991 but not to the low pre1980 levels. The collapse of the community-based medical system in rural areas and the dramatic financing changes of schistosomiasis control programmes have created major difficulties for schistosomiasis control in China.

Epidemiological features and control of schistosomiasis japonica in China

Achievements and successes have been obtained in schistosomiasis control in China. An epidemic survey was carried out and its results analyzed.

Farewell to the God of plague—The control of schistosomiasis in China

The anti-schistosomiasis campaign in China is traced through the various stages of economic and political development from pre 1949 Revolution up to the Cultural Revolution. The campaign was transformed from being essentially independent in organisation and staffed by mainly western trained experts to one that was to be closely integrated with rural commune development. With this change, there was less emphasis upon the use of chemical molluscicides and western drugs favoured by the majority of other affected countries. Instead, much greater reliance was placed upon decentralization of the medical service so that administration by health auxiliaries of labour intensive snail eradication techniques, public health control over sanitation and traditional treatment of patients suffering from the disease predominated. The campaigns were undertaken to fit in with the slack periods of the agricultural year so as to minimize the disturbance to productive work. The side-product of fertilizers, resulting from measures aimed at both snail eradication and environmental sanitation, was also an important input for agriculture. The decentralization of health services facilitated the mobilization and education of the mass population that is so important in dealing with diseases such as schistosomiasis which are largely consequent upon poverty and ignorance. The achievements in schistosomiasis control, especially in Yükiang, have also been used as a political lever to illustrate the importance of socialism, mass cooperation and self reliance in tackling the problems of disease.

Schistosomiasis in Mainland China

This article is based on a review of about 250 published reports, largely in Chinese biomedical journals, on interviews with Chinese expatriates and Japanese scientists, and on news reports from communist, noncommunist, and neutral sources. It relates the progress made toward the control of schistosomiasis in mainland China during the past 20 years. In 1949, as a result of more than a half century of neglect of the public health, central China was ravaged by schistosomiasis japonica. In 11 provinces comprising 324 districts and some of the best rice-growing lands, villages were abandoned, fields lay fallow, famine was rife, and the surviving population was ill. Surveys showed that about 10.5 million persons had schistosomiasis and another 100 million were exposed constantly to the danger of infection; also, 1.5 million cattle were infected. A national campaign against the disease utilized the abundant manpower to destroy the snail host by cleaning irrigation ditches and streams and to reclaim lands by earth fills. Preventive measures have included storage of human feces to destroy eggs. Treatment of patients has relied upon traditional galenical drugs and a 3-day treatment with tartar emetic, with a maximum dosage of 700 mg. Research has produced a series of nitrofuran compounds, some of which have given promising results. There is little doubt that great progress has been made toward the control of schistosomiasis in China. Recently, owing at least in part to the Cultural Revolution, a 7-year plan to eradicate schistosomiasis has fallen behind schedule.