Schistosomiasis remains one of the most prevalent parasitic diseases in the world with more than 200 million individuals infected, of whom over half suffer from related morbidity 14. Whilst the global burden of schistosomiasis has been estimated at 1.7 to 4.5 million disability-adjusted life years 1516, new research suggests this is a considerable underestimation of the 'true' burden of schistosomiasis 1718. However, schistosomiasis is a so-called neglected tropical disease, because it primarily affects poor rural communities in developing countries 1920.

Schistosomiasis japonica has been known in China for over two millennia, but the first case report from China was not published until 1905 21. Towards the end of the 1940s, the central government of China recognized the intolerable burden of schistosomiasis and initiated a national control programme 1112. The third national sampling survey, completed in 2004, enrolled more than 250,000 individuals from 239 villages from the seven provinces where Schistosoma japonicum remains endemic. Human prevalence ranged from 0.3% in Jiangsu province to 4.2% in Hunan province. Extrapolating these data, the total number of infected individuals in China was estimated at 726,112 in 2004 22. This estimate translates to a reduction of 16.1% when compared with the previous national survey carried out in 1995, and dramatically lower than the 10 million Chinese estimated to be infected in the mid-1950s 1112.

To illustrate how to search and make use of the Chinese scientific databases, we provide the following example. The keyword "Schistosoma" () was used to search the CNKI and VIP databases. Publication dates were set from 1990 to 2006. The results were imported into the reference management programme EndNote version 9 (Thomson ResearchSoft, Stamford, USA). The articles were stratified by journals, and sorted in descending order, i.e. number of articles published in the specified time frame. The journals were subdivided into core and non-core journals. The name, year when the journal was launched, language (abstract and main text) and open access status were recorded.

Additionally, we performed a content analysis and grouped the identified articles according to the following categories: (i) development, validation and application of new tools, (ii) epidemiology, (iii) control, and (iv) other schistosomiasis-related research. This analysis was stratified into two time periods: (i) 1990–1999 and (ii) 2000–2006.

For the period 1990–2006, we obtained 10,244 hits in the CNKI and 5,975 hits in the VIP databases when using the keyword "Schistosoma" (). Figure 1 shows the number of hits per year for the two bibliographic databases. Three points are worth highlighting. First, more references were retrieved by the CNKI database compared with VIP in each year, but this gap has narrowed over time. Second, after a sharp increase in the number of hits on the CNKI database from 1993 (n = 255) to 1994 (n = 645), the annual number of hits in subsequent years remained relatively stable (602–838). Third, there was a gradual increase in the number of hits per year in the VIP database from 96 hits in 1990 to 585 hits in 2006.

In the 17-year period we examined, the 10 leading Chinese journals publishing original research on schistosomiasis were (i) Chinese Journal of Schistosomiasis Control (Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi), (ii) Journal of Tropical Diseases and Parasitology (Re Dai Bing Yu Ji Sheng Chong Xue), (iii) Chinese Journal of Parasitology and Parasitic Diseases (Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi), (iv) Parasitoses and Infectious Diseases (Ji Sheng Chong Bing Yu Gan Ran Xing Ji Bing, as well as its former title between 1994–2002, Journal of Practical Parasitic Diseases, Shi Yong Ji Sheng Chong Bing Za Zhi), (v) Journal of Pathogen Biology (Zhongguo Bing Yuan Sheng Wu Xue Za Zhi, as well as its former title between 1988–2005, Chinese Journal of Parasitic Disease Control, Zhongguo Ji Sheng Chong Bing Fang Zhi Za Zhi), (vi) Chinese Journal of Zoonoses (Zhongguo Ren Shou Gong Huan Bing Xue Bao, as well as its former title between 1985–2005, Zhongguo Ren Shou Gong Huan Bing Za Zhi), (vii) International Journal of Medical Parasitic Diseases (Guo Ji Yi Xue Ji Sheng Chong Bing Za Zhi, as well as its former title between 1994–2005, Foreign Medicine Sciences Parasitic Diseases, Guo Wai Yi Xue Ji Sheng Chong Bing Fen Ce), (viii) Journal of Public Health and Preventive Medicine (Gong Gong Wei Sheng Yu Yu Fang Yi Xue, as well as its former title between 1994–2004, Hubei Journal of Preventive Medicine, Hubei Yu Fang Yi Xue Za Zhi), (ix) Practical Preventive Medicine (Shi Yong Yu Fang Yi Xue), and (x) China Tropical Medicine (Zhongguo Re Dai Yi Xue). The cumulative numbers of Schistosoma-specific articles that were published by these journals were 2,954, 858, 674, 607, 458, 354, 262, 217, 180 and 82, respectively. Original research articles accounted for 70.8–90.8% of the total share of published work in nine of the 10 examined journals, whereas in the International Journal of Medical Parasitic Diseases the respective fraction was only 30.2%. China Tropical Medicine was launched in 2001, which partly explains its lower quantity of published papers. These 10 journals except the International Journal of Medical Parasitic Diseases and the Journal of Public Health and Preventive Medicine are all core journals and they comply with high academic standards. Submitted manuscripts, particularly original research and reviews, are usually peer-reviewed by at least two external referees. The Chinese Journal of Parasitology and Parasitic Diseases, which is hosted by the National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention in Shanghai, for example, convenes six editorial meetings per year to come forward with final editorial decisions on which manuscripts to publish in the six issues per year. Articles usually contain Chinese and English summaries. Commencing in 2005, the International Journal of Medical Parasitic Diseases routinely publishes full-text English articles. The main body of some articles in Chinese Journal of Parasitic Disease Control, Chinese Journal of Parasitology and Parasitic Diseases and China Tropical Medicine are also published in English. The main body of articles published in the remaining six journals are usually only available in Chinese 1.

At present, only one of these 10 journals is indexed in PubMed under its Chinese name, Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi (Chinese Journal of Parasitology and Parasitic Diseases; indexed on PubMed since 1987). China Tropical Medicine is indexed on PubMed under its English name. Moreover, the following four journals are available from the 'Journals Database' in NCBI: (i) Chinese Journal of Schistosomiasis Control (Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi); (ii) Chinese Journal of Parasitology and Parasitic Diseases (Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi); (iii) Journal of Pathogen Biology (Zhongguo Bing Yuan Sheng Wu Xue Za Zhi) and (iv) Chinese Journal of Zoonoses (Zhongguo Ren Shou Gong Huan Bing Xue Bao). When searching PubMed for the term "Schistosoma" and restricting the search to the journal "Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi" and setting the temporal limits to 1990–2006, the total number of articles retrieved was 302, which translates to 44.8% of those found on the Chinese databases. None of the 10 Chinese journals examined here are yet included in the ISI Web of Knowledge. However, since the 1990s China has developed a similar citation database, namely the Chinese Science Citation Database, which contained already approximately 1,000 Chinese journals in 2001 23. With regard to open access, this feature was available for China Tropical Medicine in 2005 and 2006 via the website 24. The Chinese Journal of Parasitology and Parasitic Diseases allowed open access sine 2003 directly on the journal website 25.

The retrieved Schistosoma-specific articles from the 10 leading Chinese journals were classified into four main groups, namely (i) new tools (e.g. development, validation and application of novel diagnostics, drugs and vaccines), (ii) epidemiology (e.g. epidemiological surveys, monitoring and surveillance), (iii) control (e.g. chemotherapy, health education, water supply and sanitation, and integrated control measures), and (iv) other research. Moreover, a temporal analysis was carried out, and we compared the relative frequencies of different research topics between the time periods 1990–1999 and 2000–2006.

Table 2 shows that in the 1990s, a total of 3,240 papers pertaining to different aspects of schistosomiasis were published in the 10 journals. One of the selected journals (China Tropical Medicine) was only launched in the new millennium, so the analysis of publications in the 1990s was based on nine rather than 10 journals. The development, validation and application of new tools and epidemiological research were the most important fields of endeavour, accounting for 26.8% and 29.5% of the original research articles published, respectively. With regard to new tools, diagnostics (11.9%) and drugs (9.7%) had a considerably higher share of the total publications than vaccines (5.2%). Publications with a focus on control accounted for 21.2%. The remaining publications (22.4%) pertained to other aspects of schistosomiasis research. Between journals, the proportions of each field of Schistosoma-related publications varied. For example, the Chinese Journal of Zoonoses published a large number of schistosomiasis- research articles that pertained to new tools (49.0%). Parasitoses and Infectious Diseases had the highest proportion of epidemiological research on schistosomiasis (45.2%). The two journals Practical Preventive Medicine and Journal of Public Health and Preventive Medicine had the highest share of articles dealing with schistosomiasis control: 39.2% and 38.6%, respectively.

In the period 2000–2006, a total of 2,448 articles with an emphasis on schistosomiasis had been published in the 10 selected Chinese journals (Table 3). We found slightly higher proportions of published research pertaining to the development, validation and application of new tools (30.5%) and epidemiology (26.6%) when compared with the 1990s. On the other hand, the frequency of articles that focused on schistosomiasis control issues had not changed much (21.2% in the 1990s and 21.7% in 2000 – 2006). Generally, the proportion of articles on different aspects of schistosomiasis published by the individual journals were similar between the 1990s and the new millennium. Our results suggest that the journals examined here place particular emphasis on specific topics, and hence develop specific niches. Parasitoses and Infectious Diseases, for example, primarily covered epidemiological research on schistosomiasis (56.6%), whereas in the Chinese Journal of Zoonoses and China Tropical Medicine, more than half of the schistosomiasis-related articles focused on the development, validation and application of new tools.

A total of 328 articles were retrieved in the CNKI database when we searched for publications pertaining to the discovery, development and use of antischistosomal drugs. A significant amount of research focused on praziquantel, an antischistosomal drug discovered in the mid-1970s by Bayer in Germany 2627. The first clinical use of praziquantel in China dates back to the late 1970s 28. Since then, praziquantel has become the drug of choice for the control of schistosomiasis worldwide 1529. More than 50 million treatment courses have been administered in China and comprehensive reviews have recognised the significant contributions from Chinese clinicians and scientists towards the optimization of praziquantel use for individual treatment and community-based morbidity control 3031. The large-scale deployment of praziquantel, particularly during the 10-year World Bank Loan Project (WBLP) (1992–2001) to control schistosomiasis in China, significantly reduced the morbidity due to S. japonicum 32. To date, there is no clear evidence of clinically relevant resistance to praziquantel and there are basically no alternative drugs available, although perhaps praziquantel analogues could be developed. An important limitation of praziquantel is that it lacks activity against the young developing stages of S. japonicum 33.

In 1980, Chinese scientists discovered that artemisinin, in addition to its antimalarial activity, also exhibited antischistosomal properties 34. Studies suggested that artemisinin and its derivatives (artemether and artesunate) could kill the early developmental stages of the parasite, thus preventing the development of egg-laying adult worms, and hence preventing the associated morbidity from the immunological reactions to schistosome eggs trapped in the host tissue. In 2000, the key findings of 20 years of laboratory research and the evidence generated from clinical trials were published in English in one of the leading international parasitology journals 35. Subsequently, the data were also reviewed and published in the Chinese Journal of Schistosomiasis Control, of course in Chinese 36. In view of the artemisinins exhibiting highest activity against juvenile S. japonicum worms, ensuing research was aimed at developing the artemisinins as chemoprophylactic agents against schistosomiasis. Early administration of artemether was highly efficacious in preventing patent infections among flood relief workers exposed to schistosome-infested water 37. Importantly, this body of research stimulated scientists outside China to assess the effect of the artemisinins on the other two major human schistosome species, i.e. S. haematobium and S. mansoni, first in the laboratory, followed by clinical trials (for a recent review see 38).

From the CNKI database, a total of 290 articles pertaining to molluscicides and environmental management for schistosomiasis control were retrieved. Different approaches regarding the possible elimination of the intermediate host snail (genus: Oncomelania) have been reported, including biological methods (e.g. introduction of competitor snails), chemical control (e.g. use of molluscicides) and environmental management. With regard to molluscicides, niclosamide is the most widely used product in China 394041. A number of new compounds have been developed in China and their molluscicidal properties evaluated in the laboratory and in small pilot studies but, thus far, these compounds have not been applied on a wider scale in the field. The compounds include bromoacetamide, nicotinanilide, metaldehyde, thiocyclohexane oxalate and l,3-bis-sodium thiosulfate-2-dimethylaminopropane 424344. One of the compounds, namely 40% META liquid (a metaldehyde product licensed by Lonza Ltd., Basel, Switzerland) shows a promising molluscicidal effect against Oncomelania with low toxicity to fish. Hence this compound holds particular promise for the control of intermediate host snails, and thus warrants further investigation 45. Moreover, some compounds impede the snail's sensory system and permit an increased area of softbody exposure, thus enhancing molluscicidal activities when combined with other agents 46. Therefore, several new molluscicide formulations, including powder formulations and suspension concentrate formulations were developed to increase the efficacy of niclosamide.

Chinese researchers have also tested plant extracts from Arca catectu, Camellia oleosa, Eucalyptus camaldulensis, Jatropha curcas, Leonurus artemisia, Rhododendron sinensis, among others, for their molluscicidal properties 474849. Most of these plant extracts showed potential effect against Oncomelania, but due to low yields extracted from raw plant material, it is unlikely that these compounds will play an important role for mollusciciding programmes in the near future unless the active ingredient can be isolated and synthesized 4849.

A considerable number of articles focused on environmental management and their role for enhancing the national schistosomiasis control programme in China. Prominent examples are integration of environmental management with agriculture activities, e.g. alteration of crops planted, reclamation of land and plantations to eliminate snail habitats 50. Integration of environmental management with water resources development projects has also been carried out, e.g. cement lining of irrigation canals, installation of sinks to obstruct snail dispersal, and construction of flood gates in the connection areas of main irrigation canals or rivers. Integration of environmental management with forestry projects is another example, e.g. planting trees in the marshlands to change the ecology of snail habitats and to discourage buffaloes from grazing on the marshland, and establishing new forests in the mountainous areas 5152. Finally, integration of environmental management with agricultural projects has also been implemented, e.g. construction of fish ponds, rearrangement of irrigation systems and establishment of drainage systems.

In the lake regions of Anhui, Hubei, Hunan, Jiangsu and Jiangxi provinces, a diversity of ecological and environmental measures were employed and their effect on reducing or even eliminating the intermediate host snails and interrupting the transmission of S. japonicum was assessed. The interventions consisted of (i) constructing fish ponds, (ii) digging new ditches and filling of infested ones, (iii) reclaiming land and planting trees, (iv) earth burying, (v) concreting over ditches and (vi) combining different environmental management interventions 5354. The results of these investigations suggested that environmental management provides effective measures not only for in reducing or even eliminating snail habitats, but also for in markedly reducing the prevalence of human schistosomiasis. Comprehensive agricultural development and environment modifications as described, in conjunction with chemotherapy targeting both humans and domestic animals, demonstrated success in significantly reducing the prevalence of human schistosomiasis in China 50515253. In particular, new hydraulic technologies for preventing the spread of Oncomelania during flooding have been explored and integrated into the local control programmes in the lake region, based on an enhanced understanding of snail ecology and hydrology 515556575859.

In the mountainous areas of Sichuan and Yunnan provinces, environmental control measures such as constructing reservoirs, and modifying the complex environment showed some success in reducing the number of intermediate host snails and lowering the human infection prevalence. However, there is considerable concern that the damming of the Yangtze River, particularly due to the Three Gorges Dam, will lead to the emergence or re-emergence of schistosomiasis 54. This once again calls for rigorous monitoring and surveillance.

The development of special types of latrines with three sinks for the treatment of 'night-soil' and the production of biogas, as well as issuing new national guidelines for drinking water supply are also worth noting. Indeed, Chinese research has shown that setting aside human faecal matter intended for 'night-soil' for at least 15 days reduced miracidia hatching of schistosome eggs by up to 99.8% 50.