Contributions and achievements on schistosomiasis control and elimination in China by NIPD-CTDR.

Being a zoonotic parasitic disease, schistosomiasis was widely spread in 12 provinces of Southern China in the 1950s, severly harming human health and hindering economic development. The National Institute of Parasitic Diseases at the Chinese Center for Diseases Control and Prevention, and Chinese Center for Tropical Diseases Research (NIPD-CTDR), as the only professional institution focussing on parasitic diseases at the national level, has played an important role in schistosomiasis control in the country. In this article, we look back at the changes of schistosomiasis endemicity and the contribution of NIPD-CTDR to the national schistosomiasis control programme. We review NIPD-CTDR's activities, including field investigations, design of control strategies and measures, development of diagnostics and drugs, surveillance-response of endemic situation, and monitoring & evaluation of the programme. The NIPD-CTDR has mastered the transmission status of schistosomiasis, mapped the snail distribution, and explored strategies and measures suitable for different types of endemic areas in China. With a good understanding of the life cycle of Schistosoma japonicum and transmission patterns of the disease, advanced research carried out in the NIPD-CTDR based on genomics and modern technology has made it possible to explore highly efficient and soft therapeutic drugs and molluscicides, making it possible to develop new diagnostic tools and produce vaccine candidates. In the field, epidemiological studies, updated strategies and targeted intervention measures developed by scientists from the NIPD-CTDR have contributed significantly to the national schistosomiasis control programme. This all adds up to a strong foundation for eliminating schistosomiasis in China in the near future, and recommendations have been put forward how to reach this goal.

Schistosomiasis in a migrating population in the lake region of China and its potential impact on control operation.

Coverage of migrating people in schistosomiasis control program is a growing concern in China. Schistosomiasis caused by Schistosoma japonicum is still one of the major infectious diseases of public health importance in China though tremendous efforts have been made to control the transmission over the past decades. Along with the rapid social-economic development, migrant population has been remarkably increasing across the country. The infected migrants may introduce a new souse of infection to endemic areas or the areas where the transmission had been controlled or interrupted but the intermediate host Oncomelania snail is still present. Preliminary studies for surveillance on schistosomiasis prevalence in migrants were reported, but there is little basic information provided. We carried out an investigation on the prevalence in immigrants, emigrants and permanent residents in three villages of Hunan province located in the main endemic area of lake region, and analyzed the potential impact of migration on control practice. In the study villages, the migrant population accounts for 53.6% of the total. Schistosoma infection was detected by modified Kato-Katz method and miracidium hatching test. Questionnaire survey was conducted comprising knowledge of disease and its transmission, water contact, personal protective measures, and whether examined and treated after water contact. The survey indicated that the migrants and permanent residents had similar life style, and the majority of them experienced water contact in agricultural work or routine life activities. However, the infection rate in immigrants was significantly higher than that in permanent residents. It was also found that the migrants had significantly less knowledge about the disease than the permanent residents, and took no personal protective measures. This is due to that the control program could not cover the migrants when they were absent at the time the program being implemented. The present study suggested that the surveillance and intervention for migrants, immigrants in particular, should be included and strengthened in schistosomiasis control program and a feasible scheme be developed.

Impact and cost-effectiveness of a comprehensive Schistosomiasis japonica control program in the Poyang Lake region of China.

Schistosomiasis japonica remains a significant public-health problem in China. This study evaluated cost-effectiveness of a comprehensive schistosomiasis control program (2003-2006). The comprehensive control program was implemented in Zhangjia and Jianwu (cases); while standard interventions continued in Koutou and Xiajia (controls). Incurred costs were documented and the schistosomiasis comprehensive impact index (SCI) and cost-effectiveness ratio (Comprehensive Control Program Cost/SCI) were applied. In 2003, prevalence of Schistosoma japonicum infection was 11.3% (Zhangjia), 6.7% (Jianwu), 6.5% (Koutou), and 8.0% (Xiajia). In 2006, the comprehensive control program in Zhangjia and Jianwu reduced infection to 1.6% and 0.6%, respectively; while Koutou and Xiajia had a schistosomiasis prevalence of 3.2% and 13.0%, respectively. The year-by-year SCIs in Zhangjia were 0.28, 105.25, and 47.58, with an overall increase in cost-effectiveness ratio of 374.9%-544.8%. The SCIs in Jianwu were 16.21, 52.95, and 149.58, with increase in cost-effectiveness of 226.7%-1,149.4%. Investment in Koutou and Xiajia remained static (US$10,000 unit cost). The comprehensive control program implemented in the two case villages reduced median prevalence of schistosomiasis 8.5-fold. Further, the cost effectiveness ratio demonstrated that the comprehensive control program was 170% (Zhangjia) and 922.7% (Jianwu) more cost-effective. This work clearly shows the improvements in both cost and disease prevention effectiveness that a comprehensive control program-approach has on schistosomiasis infection prevalence.

[Establishment and application of rapid assessment system of environment with high transmission risk of schistosomiasis in marshland and lake regions. I. Establishment of an index system with Delphi method].

OBJECTIVE: To establish an index system for rapid assessment of environment with high transmission risk of schistosomiasis in marshland and lake regions. METHODS: The alternative indices were established preliminarily by the documentary method, and then the Delphi method was used two rounds to select the indices and establish the index system. The degree of familiar and authority of the experts as well as the weights of all indices were assessed. RESULTS: A total of 3 primary indices namely morbidity in domestic animals, morbidity in humans and Oncomelania snail status were established, among which the weight of morbidity in domestic animals (0.68) was the highest. Totally 16 secondary indices were established, among which the combinative weights of the positive rate of wild feces (0.09), the infection rate of livestock (0.09), the infection rate of humans (0.07), the number of cases with acute schistosomiasis (0.07), the area with infected snails (0.07), and the density of infected snails (0.07) were the highest. The coefficients of familiar degree and authority degree of the experts of the primary indices were 0.79-0.85 and 0.88-0.91, and those of the secondary indices were 0.68-0.86 and 0.77-0.91, respectively. CONCLUSIONS: The index system for rapid assessment of environment with high transmission risk of schistosomiasis in marshland and lake regions is established preliminarily. Using this system, we can assess the key endemic indices of humans, domestic animals and snails to understand the endemic situation in the investigated sites.

[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.

[Cost-effectiveness evaluation and investigation of control measure changes in areas of schistosomiasis transmission control in hilly regions of mountain areas I epidemiological investigation and analysis of prevalence factors of schistosomiasis].

OBJECTIVE: To investigate and analyze the schistosomiasis endemic status and influencing factors in areas of schistosomiasis transmission control in hilly regions of mountain areas, so as to provide the reference for establishing the strategy and measures to achieve the target of schistosomiasis transmission-interrupted in the similar areas. METHODS: Dongpo District of Meishan City, Sichuan Province, which was appropriate to the standards of schistosomiasis transmission controlled by national evaluation in 2008, was selected as a study area. The data of schistosomiasis control from 2008 to 2010 were collected. A survey for epidemiological factors was carried out from April to November in 2011. The survey of Oncomelania snails was performed with the systematic sampling combined with environmental method. The schistosome infection status of residents was investigated by the seroimmunological test and fecal hatching examination. The schistosome infection status of cattle was investigated by the plastic cup with top tube hatching method. The infested water contact of residents was investigated with questionnaire. At the same time, in 2011, a simple random sampling combined with rapid field assessment method was used to investigate the distribution of outdoor feces, outdoor feces containing schistosome eggs, snails and infected snails in two spots of Jingyang District, Deyang City and Renshou County, Meishan City which had been appropriate to the standards of schistosomiasis transmission controlled in 2006 and 2007 respectively. RESULTS: From 2008 to 2010, 182.6 thousand-213.3 thousand local residents were examined in Dongpo District, the positive rate of sero-immunological tests of population was 6.30% - 6.81%, and the infection rate of population was 0.02% -0.07% by estimated calculation. Totally 2 835-7 260 heads of cattle were examined and no positive cases were found. The areas of snail habits were 190.00-232.00 hm2, the intensities of living snails were 0.02-0.19 snails/0.1 m2, and no infected snails were found. In 2011, totally 204.4 thousand residents were examined and the positive rate of sero-immunological tests of population was 4.98% but no positive cases were founded through the parasitological tests. A total of 1 735 heads of cattle were examined and no positive cases were found. The areas of snail habits were 99.00 hm2, the intensity of living snails was 0.18 snails/ 0.1 m2, and no infected snails were found. Questionnaire analyses of a total of 537 residents in 4 villages showed that ditch, channel, pond, and paddy field were the major environments of the infested water contact of the residents. In the ditches and paddy fields, the average annual median values of water contact of residents were 15 and 20 person-times respectively before the area was appropriate to the standards of schistosomiasis transmission controlled, and 20 and 30 person-times respectively after the area was appropriate to the standards of schistosomiasis transmission controlled, and there were no significant differences (chi(ditch2) = 1.61, chi(padd field2) = 0.03, both P > 0.05). Whereas, in the channels and ponds, the average annual median values of water contact were 15 and 30 person-times respectively before the area was appropriate to the standards of schistosomiasis transmission controlled, but they were significantly reduced after the area was appropriate to the standards of schistosomiasis transmission controlled (chi(channel2) =10.35, chi(pond2) =18.69, both P < 0.01). In 2011, the rapid field investigation and assessment showed that the average appearance rates of snails through screening were 60.15% and 12.12% respectively in the 2 villages. The average densities of living snails were 1.19 snails/0.1m2 and 0.20 snails/0.1m2 respectively in the 2 villages, and there were no infected snails. A total of 78 outdoor feces of cattle and sheep were collected and the fecal hatching examinations showed that there were no positives. CONCLUSIONS: After the schistosomiasis endemic areas in hilly regions of mountain areas are appropriate to the standards of schistosomiasis transmission controll, the achievements have been consolidated. However, the potential schistosomiasis endemic factors still exist, such as the high positive rate of schistosome sero-immunological tests in population, frequently bovine flowing, and no obviously decrease of the snail area and density of living snails. Therefore, it is an urgent need to develop more suitable new technologies and measures to accelerate the process of schistosomiasis prevention and control.

[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.

[Burden of disease in schistosomiasis japonica. I. Calculation and evaluation of years lived with disability of chronic schistosomiasis].

OBJECTIVE: To discuss the evaluation index of the disease burden of chronic schistosomiasis and its calculation methods. METHODS: The epidemiological data came from the thematic research carried out in two schistosome-endemic counties in lake areas between 2004 and 2005. The specific prevalence rates by age group, gender and endemic type were calculated. According to the age-specific disability weight obtained in the thematic research, the years lived with disability (YLDs) and the rates of YLD of stratified samples by age and gender, and the total YLDs of the two counties were calculated. RESULTS: The total YLDs were 1 056.26 and 3 967.43 person-years in Dangtu and Hanshou counties, respectively. The contributing rate of Grade I type village to the total YLDs of two counties was 37.95% (40.08% in Dangtu and 37.39% in Hanshou). For different stratums by age and gender, the older ones and male tended to have larger YLDs. Compared to the non-endemic areas, chronic schistosomiasis brought an average extra of 4.398 and 1.505 years per 1 000 person to population in Dangtu and Hanshou counties, respectively. CONCLUSION: The evaluation to YLDs of chronic schistosomiasis is helpful for prioritizing intervention areas and population, as well as providing a new index for the evaluation of effectiveness of control measures.

[Burden of disease in schistosomiasis japonica. II. Measurement of health inequalities due to chronic schistosomiasis].

OBJECTIVE: To measure and evaluate the health inequalities due to chronic schistosomiasis japonica. METHODS: Based on years lived with disability (YLD) caused by chronic schistosomiasis, a concentration index and Gini index, along with a concentration curve and Lorenz curve, the health inequalities between sexes, age groups or endemicities were identified and quantified. RESULTS: The age concentration index was 0.395 of females and 0.380 of males, with no significant difference between them. More than 60% of YLD was contributed by those aged > or = 45 years old who accounted for about a third of total population in both sexes. Gini index was 0.666 of Dangtu County and 0.451 of Hanshou County, and 60% of YLD was contributed by the highly endemic villages. CONCLUSIONS: The concentration index and Gini index could quantify the magnitude of health inequalities well. The priority of morbidity control should be given to those aged > or = 45 years old and living in highly endemic villages.

Tools to support policy decisions related to treatment strategies and surveillance of Schistosomiasis japonica towards elimination.

BACKGROUND: Appropriate diagnostics to monitor disease trends and assess the effectiveness and impact of interventions are essential for guiding treatment strategies at different thresholds of schistosomiasis transmission and for certifying elimination. Field validation of these assays is urgently needed before they can be adopted to support policy decisions of the national programme for control and elimination of schistosomiasis in P.R. China. We compared the efficacy and utility of different immunoassays in guiding control strategies and monitoring the endemic status of S. japonicum infections towards elimination. METHODOLOGY/PRINCIPAL FINDINGS: A cross-sectional survey was conducted in seven villages with different transmission intensities settings to assess the performance and utility of three immunoassays, e.g., an indirect hemagglutination assay (IHA_JX), an enzyme linked immunosorbent assay (ELISA_SZ), and a dot immunogold filtration assay (DIGFA_SH). 6,248 individuals aged 6-65 years old who gave consent and supplied their stool and blood samples were included for data analysis. Results showed that ELISA_SZ performed significantly higher sensitivity (95.45%, 95%CI: 92.94-97.97%) than IHA_JX (87.59%, 95%CI: 83.51-91.49%) and DIGFA_SH (79.55%, 95%CI: 74.68-84.41%), especially in subgroups with very low infection intensity. The specificity of ELISA_SZ, IHA_JX, DIGFA_SH in 6-9 year olds with occasional exposure was nearly 90%. DIGFA_SH performed the highest screening efficacy for patients among three assays with overall positive predicative value of 13.07% (95%CI: 11.42-14.72%). We found a positive correlation of antibody positive rate of IHA_JX with results of stool examination in age strata (r = 0.70, P<0.001). Seropositivity of IHA_JX in children aged 6-9 years old showed an excellent correlation with prevalence of schistosome infection in the seven communities (r = 0.77, P<0.05). CONCLUSIONS/SIGNIFICANCE: Studies suggest that ELISA_SZ could be used to guide selective chemotherapy in moderate or low endemic regions. IHA_JX could be used to as a surveillance tool and for certifying elimination of schistosomiasis through monitoring children as a sentinel population.

[Burden of disease in schistosomiasis japonica III household socioeconomic determinants of chronic schistosomiasis].

OBJECTIVE: To explore the socioeconomic determinants of chronic schistosomiasis japonica at household level. METHODS: The socioeconomic status of case and control families in lake and marsh schistosomiasis endemic areas were investigated by questionnaire, socioeconomic factors were analyzed by the principle components analysis, and the wealth index were calculated to evaluate the economic status at household level. Then the relation between schistosome infection and some influencing factors were analyzed by two-level Logistic regression model. RESULTS: A total of 2 716 households in 91 villages were investigated, among which 1 050 were case families and 1 666 were control families. The values of the first eigenvector of stone/brick house, house with > or = 2 floors, black/white TV, colour TV, washing machine, refrigerator, side occupation were -0.42, 0.46, -0.45, 0.46, 0.32, 0.24 and 0.16, respectively, which suggested that the first eigenvector was the comprehensive index reflecting family wealth. The results of Logistic regression model showed that there were 4 household factors significantly relating to chronic schistosomiasis, namely, the distance from residence to schistosome-infested water, source of washing water, economic status, and wet land area per capita, among which the factor that the distance from residence to schistosome - infested water < 100 m with the highest (OR = 12.590, P = 0). CONCLUSION: In the lake and marsh endemic areas, health education and other intervention to the poor family living along river or lake without safe water supply should be strengthened to control schistosomiasis.

A strategy to control transmission of Schistosoma japonicum in China.

BACKGROUND: Schistosoma japonicum causes an infection involving humans, livestock, and snails and is a significant cause of morbidity in China. METHODS: We evaluated a comprehensive control strategy in two intervention villages and two control villages along Poyang Lake in the southeastern province of Jiangxi, where annual synchronous chemotherapy is routinely used. New interventions, implemented from 2005 through 2007, included removing cattle from snail-infested grasslands, providing farmers with mechanized farm equipment, improving sanitation by supplying tap water and building lavatories and latrines, providing boats with fecal-matter containers, and implementing an intensive health-education program. During the intervention period, we observed changes in S. japonicum infection in humans, measured the rate of infection in snails, and tested the infectivity of lake water in mice. RESULTS: After three transmission seasons, the rate of infection in humans decreased to less than 1.0% in the intervention villages, from 11.3% to 0.7% in one village and from 4.0% to 0.9% in the other (P<0.001 for both comparisons). The rate of infection in humans in control villages fluctuated but remained at baseline levels. In intervention villages, the percentage of sampling sites with infected snails decreased from 2.2% to 0.1% in one grassland area and from 0.3% to no infection in the other (P<0.001 for both comparisons). The rate of infection in mice after exposure to lake water decreased from 79% to no infection (P<0.001). CONCLUSIONS: A comprehensive control strategy based on interventions to reduce the rate of transmission of S. japonicum infection from cattle and humans to snails was highly effective. These interventions have been adopted as the national strategy to control schistosomiasis in China.

An economic evaluation of the national schistosomiasis control programme in China from 1992 to 2000.

The World Bank Loan Project, by far the largest effort in China for schistosomiasis control since control activities were initiated in the mid 1950s, was carried out for a 9-year period commencing in 1992 in the 8 provinces where Schistosoma japonicum remained endemic when the project started. To evaluate its impact, a retrospective economic evaluation was done in 2001. Six representative counties, i.e. Huarong in Hunan province, Qianjiang in Hubei province, Yugan in Jiangxi province, Tongling in Anhui province, Xichang in Sichuan province and Dali in Yunnan province, were selected for the study. The total financial input in these counties from 1992 to 2000 was RMB Yuan 90.334 million with the World Bank loan accounting for 40.9%. Control efforts resulted in reduction of human prevalence rates in the six counties from 0.7-9.0% in 1992 to 0.1-2.7% in 2000. With regard to S. japonicum infection in bovines, a high reduction was observed in Qianjiang, and smaller decreases were noted in four counties, while there was an increase in Dali. In general, the areas infested by the intermediate host snail fluctuated around the initial level. The net benefit-cost ratio was 6.20, which means that this project gained US$ 6.20 for every dollar spent. The correlation coefficients of the net benefit-cost ratio to the human and bovine infection rates at the beginning of the project were 0.55 and 0.66, respectively. It is conceivable that further progress in schistosomiasis control is an important feature for sustained growth of the local economy, particularly in areas where control of the disease has been most challenging.

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.