[Effects of nitroquine on the development of Plasmodium yoelii at different stages in Anopheles stephensi]

OBJECTIVE

To investigate the effects of nitroquine on the development of different stages of Plasmodium yoelii in Anopheles stephensi.

METHODS

An. stephensi mosquitoes were fed with conventional sucrose water or sucrose water containing 100 μmol/L nitroquine one day prior to P. yoelii infection. Following starvation for 24 hours, mosquitoes were fed with the blood of Kunming mice infected with P. yoelii, and the number of oocysts was observed in the stomach of An. stephensi. After 6 days and 14 days of infection, the mosquitoes were starved for 24 hours, and then fed with conventional sucrose water or nitroquine treated sucrose water. The An. stephensi mosquitoes were starved for 24 hours 6 and 14 days post-infection with P. yoelii, and then fed with conventional sucrose water or nitroquine-containing sucrose water, the numbers of P. yoelii sporozoites were examined in the hemolymph and salivary glands of An. stephensi.

RESULTS

Following exposure to nitroquine-containing sucrose water one day prior to P. yoelii infections, the number of P. yoelii oocysts was significantly lower in the An. stephensi stomach on day 7 (119.2 ± 16.1 vs. 207.3 ± 21.8; t = 3.207, P < 0.05). After conventional sucrose water was ceased for 24 hours on day 6, and An. stephensi was fed with nitroquine-containing sucrose water, the number of P. yoelii sporozoites peaked in the hemolymph on day 14 in the nitroquine treatment group (952.3 ± 22.7) and on day 12 in the sucrose water treatment group (1 287.0 ± 39.0), and there was a significant difference in the number of sporozoites in the salivary glands between the nitroquine treatment group and the sucrose water treatment group (9 467.0 ± 1 304.0 vs. 10 533.0 ± 758.7; t = 0.707, P = 0.506) on day 17. After conventional sucrose water was ceased for 24 hours on day 14, and An. stephensi was fed with nitroquine-containing sucrose water, the number of sporozoites in the salivary glands was significantly greater in the nitroquine treatment group than in the sucrose water treatment group (21 900.0 ± 2 613.0 vs. 10 533.0 ± 732.3; t = 4.188, P < 0.05).

CONCLUSIONS

Nitroquine treatment exhibits diverse effects the development of different stages of P. yoelii, and nitroquine treatment may reduce the transmission of P. yoelii in uninfected An. stephensi.

[Performance of loop-mediated isothermal amplification (LAMP) assay for detection of Schistosoma japonicum infection in Oncomelania snails in schistosomiasis transmission-interrupted regions]

OBJECTIVE

To compare the effectiveness of loop-mediated isothermal amplification (LAMP) assay and microscopic examinations for detection of Schistosoma japonicum infections in Oncomelania hupensis in transmission-interrupted regions, so as to provide insights into the optimization of snail surveillance tools in these regions.

METHODS

Four hilly schistosomiasis-endemic villages where transmission interruption was achieved were selected in Heqing County of Yunnan Province as the study villages, including Xinzhuang and Gule villages in hilly regions and Lianyi and Yitou villages in dam regions. Snail survey was performed by means of systematic sampling combined with environmental sampling in July 2018. All captured snails were identified for S. japonicum infections using microscopy. In addition, 10 to 20 snails were randomly sampled from each snail habitat following microscopy, numbered according to environments and subjected to LAMP assay. The positive rate of settings with S. japonicum-infected snails was compared among villages.

RESULTS

A total of 7 949 living snails were captured from 83 snail habitats in 4 villages, and no S. japonicum infection was detected in snails. There were 226 mixed samples containing 1 786 snails subjected to LAMP assay, and positive LAMP assay was found in 3 mixed samples from 3 snail habitats in 2 dam villages. The positive rates of settings with S. japonicum-infected snails were comparable between Lianyi Village (one setting) and Yitou Village (2 set tings) (5.89% vs. 14.29%, P = 0.344). However, the overall positive rate of settings with S. japonicum-infected snails was significantly higher in dam villages (9.67%, 3/31) than in hilly villages (0) (P = 0.048).

CONCLUSIONS

LAMP assay is more sensitive to detect S. japonicum infections in O. hupensis than conventional microcopy method, which may serve as a supplementary method for detection of S. japonicum infections in O. hupensis in high-risk snail habitats in hilly transmission-interrupted regions.

[Expert consensus on the strategy and measures to interrupt the transmission of schistosomiasis in China]

Since 2015 when the transmission of schistosomiasis was controlled in China, the country has been moving towards elimination of schistosomiasis, with the surveillance-response as the main interventions for schistosomiasis control. During the period of the 13th Five-Year Plan, the transmission of schistosomiasis had been interrupted in four provinces of Sichuan, Jiangsu, Yunnan and Hubei and the prevalence of schistosomiasis has been at the historically lowest level in China. As a consequence, the goal set in The 13th Five-Year National Schistosomiasis Control Program in China is almost achieved. However, there are multiple challenges during the stage moving towards elimination of schistosomiasis in China, including the widespread distribution of intermediate host snails and complicated snail habitats, many types of sources of Schistosoma japonicum infections and difficulty in management of bovines and sheep, unmet requirements for the current schistosomiasis control program with the currently available tools, and vulnerable control achievements. During the 14th Five-Year period, it is crucial to consolidate the schistosomiasis control achievements and gradually solve the above difficulties, and critical to provide the basis for achieving the ultimate goal of elimination of schistosomiasis in China. Based on the past experiences from the national schistosomiasis control program and the challenges for schistosomiasis elimination in China, an expert consensus has been reached pertaining to the objectives, control strategy and measures for The 14th Five-Year National Schistosomiasis Control Program in China, so as to provide insights in to the development of The 14th Five-Year National Schistosomiasis Control Program in China.

Forecasting the effectiveness of the DeWorm3 trial in interrupting the transmission of soil-transmitted helminths in three study sites in Benin, India and Malawi

Background

The DeWorm3 project is an ongoing cluster-randomised trial assessing the feasibility of interrupting the transmission of soil-transmitted helminths (STH) through mass drug administration (MDA) using study sites in India, Malawi and Benin. In this article, we describe an approach which uses a combination of statistical and mathematical methods to forecast the outcome of the trial with respect to its stated goal of reducing the prevalence of infection to below 2%.

Methods

Our approach is first to define the local patterns of transmission within each study site, which is achieved by statistical inference of key epidemiological parameters using the baseline epidemiological measures of age-related prevalence and intensity of STH infection which have been collected by the DeWorm3 trials team. We use these inferred parameters to calibrate an individual-based stochastic simulation of the trial at the cluster and study site level, which is subsequently run to forecast the future prevalence of STH infections. The simulator takes into account both the uncertainties in parameter estimation and the variability inherent in epidemiological and demographic processes in the simulator. We interpret the forecast results from our simulation with reference to the stated goal of the DeWorm3 trial, to achieve a target of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\le 2\%$$\end{document}≤2% prevalence at a point 24 months post-cessation of MDA.

Results

Simulated output predicts that the two arms will be distinguishable from each other in all three country sites at the study end point. In India and Malawi, measured prevalence in the intervention arm is below the threshold with a high probability (90% and 95%, respectively), but in Benin the heterogeneity between clusters prevents the arm prevalence from being reduced below the threshold value. At the level of individual study arms within each site, heterogeneity among clusters leads to a very low probability of achieving complete elimination in an intervention arm, yielding a post-study scenario with widespread elimination but a few ‘hot spot’ areas of persisting STH transmission.

Conclusions

Our results suggest that geographical heterogeneities in transmission intensity and worm aggregation have a large impact on the effect of MDA. It is important to accurately assess cluster-level, or even smaller scale, heterogeneities in factors which influence transmission and aggregation for a clearer perspective on projecting the outcomes of MDA control of STH and other neglected tropical diseases.

[A high-quality driver to accelerate the progress towards schistosomiasis elimination by science and technology-led innovation in Jiangsu Province]

Schistosomiasis was once hyper-endemic in Jiangsu Province. During the past seven decades, the professionals working in schistosomiasis control from Jiangsu Province insisted on scientific and precision control all the time, created a series of replicable and generalizable "Jiangsu experiences". These practices have developed a number of tools and approaches that have been employed in schistosomiasis control programs in main endemic foci of China. More importantly, the successful experiences from national schistosomiasis control programs of China have been firstly transferred to Africa by professionals from Jiangsu Province, and remarkable achievements have been obtained for the control of schistosomiasis haematobia in Zanzibar.

[Progress of interruption of schistosomiasis transmission in Jiangsu Province]

Schistosomiasis was once heavily endemic in Jiangsu Province. Following the control efforts for several decades, schistosomiasis was almost eradicated in all endemic counties in Jiangsu Province in 1980, and transmission control was achieved in the province in 2011. According to the principle of "implementing the control measures with adaptation to local circumstances and guiding the control programs with classified interventions", an integrated strategy with emphasis on the management of both infectious sources and snails has been recently employed for schitsosomiasis control in Jiangsu Province. In addition, a sensitive and highly effective surveillance system has been built and the application of novel techniques and information construction has been intensified to effectively interrupt the transmission of schistosomiasis in the Province. Transmission interruption of schistosomiasis was achieved in all endemic counties in Jiangsu Province. The paper summarizes the endemic situation of schistosomiasis, progress of schistosomiasis control, and major schistosomiasis control measures implemented during the stage of transmission interruption in Jiangsu Province.

[Surveillance of schistosomiasis 34 years after transmission interruption in Songjiang District, Shanghai City]

OBJECTIVE

To analyze the surveillance data after schistosomiasis transmission interruption from 1985 to 2018, so as to provide scientific basis for the future prevention and control of schistosomiasis.

METHODS

The data pertaining to snail survey, surveillance of schistosomiasis in humans and livestock, and health education were collected and analyzed in Songjiang District after schistosomiasis transmission interruption from 1985 to 2018.

RESULTS

From 1985 to 2018, there were 8 townships, 68 villages and 1 462 settings with snails in Songjiang District, covering an area of 96.399 hm². There were 4 townships and 59 villages with snails newly identified in previously schistosomiasis non-endemic areas, with emerging snail habitats of 60.161 hm². A total of 26 148 snails were captured, and no infections were detected. The snail habitats were mainly distributed in the river course, ditches and farmlands, which accounted for 45.28%, 33.17% and 21.55% of total snail habitats, respectively. A total of 245 955 humans were subjected to the serological test, with a positive rate of 0.03%, and 37 humans were subjected to the parasitological test, with 3 positives detected. These three egg-positives were all imported chronic cases with schistosomiasis. A total of 9 109 livestock were detected using the serological test, and no infection was found. Most of the awareness rate of schistosomiasis control knowledge and the rate of correct behavior formation were over 80% in residents and students.

CONCLUSIONS

The achievements of schistosomiasis control are consolidated in Songjiang District; however, there are still risk factors of schistosomiasis transmission, including residual snails, snail diffusion and importation of external source of infection. The future surveillance of schistosomiasis should focus on snails and sources of infection.

[Emergency treatment of schistosomiasis outbreaks in transmission - interrupted mountainous and hilly areas]

In China, the mountainous and hilly schistosomiasis-endemic areas are mainly distributed in 2 provinces of Sichuan and Yunnan. Although great success has been achieved in schistosomiasis control in mountainous and hilly areas, there is a risk of re-emerging schistosomiasis in local areas. Hereby, we described the emergency treatment of two schistosomiasis outbreaks that occurred in transmission-interrupted areas of Yunnan Province in 2011 and 2013, pointed out the risk of schistosomiasis rebounding in mountainous and hilly areas and proposed some suggestions.

[Strategy of schistosomiasis elimination and its effects in Jinhu County, Jiangsu Province]

OBJECTIVE

To understand the strategy of schistosomiasis elimination and its effects in Jinhu County, Jiangsu Province.

METHODS

The data of schistosomiasis control in Jinhu County at different stages from 1970 to 2017 were collected and analyzed.

RESULTS

From 1970 to 2017, there were three stages of schistosomiasis control, including transmission control, transmission interruption, and monitoring and elimination stages in Jinhu County. The main measures included Oncomelania hupensis snail control, infectious source control, and health education. A total of area of 290 691.78 hm² was detected in Jinhu County, and the area with snails was 3 420.98 hm². There were 8 729.37 hm² area with snails was controlled. Since 2014, no O. hupensis snails were found. A total of 525 377 person-times were examined for schistosomiasis, with 2 815 schistosomiasis patients identified, and 2 844 person-times were treated by chemotherapy. In addition, 977 cases received the expand chemotherapy. Since 1990, no local schistosome-infected persons were found. In 2017, the awareness rate of schistosomiasis control knowledge and the correct rate of health behavior were increased by 54.59% and 14.23% respectively compared with those in 1992.

CONCLUSIONS

The comprehensive schistosomiasis control measures implemented in Jinhu County at different periods have achieved remarkable outputs and accelerated the schistosomiasis elimination process. However, the precise control measures should be implemented in the future to consolidate the prevention and control achievements.

[Application and effect of integrated control model of schistosomiasis interruption in mountainous and hilly endemic regions]

OBJECTIVE

To explore the integrated schistosomiasis control model in mountainous and hilly endemic regions, so as to provide insights into the development of the schistosomiasis elimination strategy.

METHODS

Five hilly and mountainous areas endemic for schistosomiasis were selected as the integrated control demonstration areas in Sichuan Province from 2011 to 2015. According to the epidemic characteristics, economic levels and overall development planning of the demonstration areas, the goals, strategies and measures were developed, and the effectiveness of schistosomiasis control was evaluated following implementation of the integrated control.

RESULTS

The support system of the integrated schistosomiasis control model was built in the integrated control demonstration areas in Sichuan Province from 2011 to 2015, and five ecological, industrialized and sustainable development models of integrated schistosomiasis control were developed, including integration of balancing rural and urban development, systematic ecological improvement, intensified ecological agriculture, scientific management and health education of schistosomiasis control and ecological ethnic circular economy. Since the implementation of the integrated schistosomiasis control model, the snail habitats were completely changed. Until 2015, 92.0% of all historical areas with snails were managed, the coverage of safe drinking water was 100.0%, and more than 95.0% of the livestock were fenced. The coverage of sanitary toilets increased by 93.0%, 96.8%, 78.8%, 87.1% and 82.0% from 2011 to 2015, respectively, and the farmers'mean yearly income increased by 32.7% in the demonstration areas. From 2011 to 2015, the seroprevalence of human Schistosoma japonicum infections reduced from 3.1% in 2011 to 1.6% in 2015 in the demonstration areas, and no egg-positives were identified. In addition, the number of fenced bovines reduced year by year, and no egg-positives were detected. The areas of snail habitats were 398.7, 108.2 hm² and 52.9 hm² in the demonstration areas from 2011 to 2013, with no infected snails found, and no snails were detected since 2014. The awareness of schistosomiasis control knowledge and percentage of correct behavior formation increased year by year among residents in the demonstration areas from 2011 to 2015.

CONCLUSIONS

The five integrated schistosomiasis control models meet the needs of the current schistosomiasis control activities in mountainous and hilly endemic areas of Sichuan Province, and achieve the goals of controlling the sources of S. japonicum infections, economic development, social progress and improving the ecological environment, which provides new insights into schistosomiasis elimination in the country.

[Progress and challenges of schistosomiasis elimination in China]

Schistosomiasis is an old and geographically widespread parasitic disease that severely damages human health and affects socioeconomic development in China. The implementation of the integrated strategy with emphasis on controlling the source of Schistosoma japonicum infection and the National Mid- and Long-Term Plan for Schistosomiasis Prevention and Control (2004-2015) in China greatly facilitated the progress towards the elimination of schistosomiasis in China. Since transmission control of schistosomiasis was achieved in 2015, the goal of the national schistosomiasis control program has moved to transmission interruption and elimination in China. Because of the impacts of natural and social factors, and the new situation, new task and new demands following the continuous decline in the endemic situation of schistosomiasis, several challenges exist to achieve the goal of schistosomiasis elimination nationwide. This paper analyzed the current endemic status of schistosomiasis, progress and challenges of schistosomiasis elimination, and proposed some suggestions for the national chistosomiasis elimination program in China.

Integrating ecological approaches to interrupt schistosomiasis transmission: opportunities and challenges

Background

The development of agenda for global schistosomiasis elimination as a public health problem generates enthusiasms among global health communities, motivating great interests in both research and practice. Recent China-Africa schistosomiasis control initiatives, aiming to enhance collaboration on disease control in African countries, reflect in part that momentum. Yet there is a pressing need to know whether the Chinese experiences can be translated and applied in African settings.

Main body

China’s remarkable achievements in schistosomiasis control programme, associated experiences and lessons, have much to offer to those combating the disease. Central to the success of China’s control programmes is a strategy termed “integrated control” – integrating environmental approaches (e.g. improved sanitation, agricultural and hydrological development and management), which target different phases of the parasite transmission system, to chemical-based drug treatment and mollusciciding. Yet, despite significant measurable public health benefits, such integration is usually based on field experience and remains largely uncharacterized in an ecological context. This has limited our knowledge on relative contributions of varying components of the integrated control programme to the suppression of disease transmission, making it challenging to generalize the strategy elsewhere. In this opinion article, we have described and discussed these challenges, along with opportunities and research needs to move forward.

Conclusions

There is an urgent need to formalize an ecological framework for the integrated control programme that would allow research towards improved mechanistic understanding, quantification, and prediction of the control efforts.

Electronic supplementary material

The online version of this article (10.1186/s40249-018-0506-4) contains supplementary material, which is available to authorized users.

[Study on interventions based on systematic ecological system construction to interrupt transmission of schistosomiasis in hilly endemic regions]

OBJECTIVE

To study the effectiveness of comprehensive control measures based on systematic ecological system construction to interrupt the transmission of schistosomiasis in hilly endemic regions in Sichuan Province, so as to provide the evidence for adjustment of schistosomiasis prevention and control strategies.

METHODS

A high endemic area of schistosomiasis, Panao Township of Dongpo District in Meishan City, was selected as a demonstration area. The comprehensive measures for schistosomiasis control with focus on systematic ecological management were implemented, and the income of residents, indexes of schistosomiasis control effect and so on were investigated before and after the intervention and the results were compared.

RESULTS

The project based on systematic ecological system construction started in 2009 and 317.351 million Yuan was put into the construction. The construction included economic forest plant base (1 866.68 hm², 72.66% of the total farmland areas), ecological protection gardens (585.35 hm²) and so on. Totally 97.04% of historical areas with Oncomelania hupensis snails were comprehensively improved. In 2015, the peasants´ pure income per capita increased 4 938 Yuan, with the average annual growth rate of 14.69%. All the farm cattle were replaced by the machine. The benefit rate of water improvement was increased by 52.84% and the coverage rate of harmless toilets increased by 18.30%. The positive rate of serological tests for schistosomiasis decreased from 7.69% to 3.50%, and the positive rate of parasitological tests decreased from 1.18% to 0. The area with snails was decreased from 23.33 hm² to 0. The awareness rate of schistosomiasis control knowledge and correct behavior rate of the residents increased from 85.50% and 82.60% to 95.70% and 93.90% respectively.

CONCLUSIONS

The comprehensive schistosomiasis control measures based on systematic ecological management are conform to the currently actual schistosomiasis prevention and control work in hilly endemic regions, and have good ecological economic benefit and schistosomiasis control effectiveness, which provide an effectively new model of prevention and control for advancing process, consolidating the effect, finally realizing goal of interruption and elimination of schistosomiasis in hilly endemic regions.

[Strategy of transmission interruption of schistosomiasis and its effects in Runzhou District, Zhenjiang City, Jiangsu Province]

OBJECTIVE

To evaluate the effects of the strategy of transmission interruption of schistosomiasis in Runzhou District, Zhenjiang City, Jiangsu Province.

METHODS

The comprehensive prevention and control strategy was carried out in RunzhouDistrict, Zhenjiang City, Jiangsu Province. The strategy was relied mainly on the Oncomelania hupensis snail control, extended chemotherapy of schistosomiasis in residents and the health education. The infection rate of schistosomiasis in residents, area with snails, area with snails controlled, and the rates of awareness and correct behavior of schistosomiasis were as evaluation indexes.

RESULTS

The area with snails controlled was 7 091.50 hm² in Runzhou District, Zhenjiang City from 2001 to 2016. The area with snails reduced year by year from 2001 to 2016. There was a negative correlation between the coverage intensity of snail control and the area with snails (r = -0.874, P = 0). There were 1 703 serum positive and 199 fecal positive people of schistosomiasis in the permanent residents from 2001 to 2016. These serum and fecal positive people of schistosomiasis were all treated with praziquantel. The serum positive rate of schistosomiasis in the permanent residents dropped to below 1.0% after 2005. The fecal positive patients were not found in 2004 and later. Totally 189 639 people received the questionnaire survey for the knowledge of schistosomiasis control from 2001 to 2016. The rates of awareness and correct behavior of schistosomiasis were raised in the residents year by year. The goal of the transmission interruption of schistosomiasis came to true in Runzhou District, Zhenjiang City in 2016.

CONCLUSIONS

The comprehensive prevention and control strategy including mainly the snail control, extended chemotherapy of schistosomiasis and health education could achieve the goal of transmission interruption of schistosomiasis in the areas of marshland along the Yangtze River.

Helminth lifespan interacts with non-compliance in reducing the effectiveness of anthelmintic treatment

Background

The success of mass drug administration programmes targeting the soil-transmitted helminths and schistosome parasites is in part dependent on compliance to treatment at sequential rounds of mass drug administration (MDA). The impact of MDA is vulnerable to systematic non-compliance, defined as a portion of the eligible population remaining untreated over successive treatment rounds. The impact of systematic non-compliance on helminth transmission dynamics - and thereby on the number of treatment rounds required to interrupt transmission - is dependent on the parasitic helminth being targeted by MDA.

Results

Here, we investigate the impact of adult parasite lifespan in the human host and other factors that determine the magnitude of the basic reproductive number R₀, on the number of additional treatment rounds required in a target population, using mathematical models of Ascaris lumbricoides and Schistosoma mansoni transmission incorporating systematic non-compliance. Our analysis indicates a strong interaction between helminth lifespan and the impact of systematic non-compliance on parasite elimination, and confirms differences in its impact between Ascaris and the schistosome parasites in a streamlined model structure.

Conclusions

Our analysis suggests that achieving reductions in the level of systematic non-compliance may be of particular benefit in mass drug administration programmes treating the longer-lived helminth parasites, and highlights the need for improved data collection in understanding the impact of compliance.

[Study of schistosomiasis transmission interruption based on intensive agriculture]

Objective To study the effect of schistosomiasis transmission interruption model based on intensive agriculture in hilly endemic areas, so as to provide the reference for the similar endemic areas. Methods Based on the development of intensive agriculture in Guanghan City, a comprehensive demonstration area of schistosomiasis control with measures such as new rural construction, hardening ditches, the adjustment of industrial structure and water remediation measures was constructed. Jinhua, Shiguan and Hongyan villages were chosen as the evaluation sites to comparatively analyze the indexes of intensive agriculture and schistosomiasis control effects. Results Compared with the demonstration area before construction, in 2014, the harden rates of ditches and village roads were increased by 49.57% and 39.33% respectively; and the proportion of agricultural machinery increased by 25%. The positive rate of serological tests of schistosomiasis was decreased by 81.74%. The Oncomelania hupensis snail area was decreased from 2.44 hm² (2007) to 0 (2014). The awareness rate of schistosomiasis control knowledge and correct behavior rate of the residents were increased from 51.28% and 90.85% to 91.29% and 97.69% respectively. The experience of the demonstration area ensured the entire Guanghan District achieved the schistosomiasis transmission interruption criterion at the end of 2014. Conclusions The schistosomiasis control model of intensive agriculture combined with other comprehensive measures has a good effect on interrupting the endemic of schistosomiasis, and it can realize the sustainable development of the agricultural economy and schistosomiasis control.

[Study on risk assessing indicator system after schistosomiasis transmission interruption in Wuxi City]

OBJECTIVE

To establish a risk assessing indicator system after the transmission interruption of schistosomiasis in Wuxi City, so as to provide evidences for formulating strategies on schistosomiasis control and prevention.

METHODS

A primary risk assessing indicator system was established based on the literature review. Alternative indicators were scored and screened to establish a final indicator system through two rounds of Delphy method and the related normalized weights and combined weights were also calculated.

RESULTS

The risk assessing indicator system was established through two rounds of expert consultation including 3 first grade indicators and 15 second grade indicators. Among the first grade indicators, the normalized weights of natural environment, key populations and social environment were 0.370 6, 0.292 9 and 0.336 5, respectively. Among the second grade indicators, the migrant population accounted for the highest combined weight of 0.125 2 compared to domestic animal of 0.037 1. The authority degree among the first grade indicators was between 0.91 and 0.93, while the authority degree among the second grade indicators was between 0.79 and 0.92.

CONCLUSIONS

The scientific and authoritative risk assessing indicator system after the transmission interruption of schistosomiasis is established, which provides the evidences for risk assessment on schistosomiasis transmission in Wuxi City.

Interruption of schistosomiasis transmission in mountainous and hilly regions with an integrated strategy: a longitudinal case study in Sichuan, China

Background

Schistosomiasis remains a major public health concern in China. Since 2004, an integrated strategy was developed to control the transmission of Schistosoma japonicum in China. However, the long-term effectiveness of this integrated strategy for the interruption of schistosomiasis transmission remains unknown in the mountainous and hilly regions of China until now. This longitudinal study aims to evaluate the effectiveness of the integrated strategy on transmission interruption of schistosomiasis in Sichuan Province from 2005 through 2014.

Methods

The data regarding replacement of bovines with machines, improved sanitation, access to clean water, construction of public toilets and household latrines, snail control, chemotherapy, and health education were captured from the annual report of the schistosomiasis control programmes in Sichuan Province from 2005 to 2014, and S. japonicum infection in humans, bovines and snails were estimated to evaluate the effectiveness of the integrated strategy.

Results

During the 10-year period from 2005 through 2014, a total of 536 568 machines were used to replace bovines, and 3 284 333 household lavatories and 15 523 public latrines were built. Tap water was supplied to 19 116 344 residents living in the endemic villages. A total of 230 098 hm² snail habitats were given molluscicide treatment, and 357 233 hm² snail habitats received environmental improvements. There were 7 268 138 humans and 840 845 bovines given praziquantel chemotherapy. During the 10-year study period, information, education and communication (IEC) materials were provided to village officers, teachers and schoolchildren. The 10-year implementation of the integrated strategy resulted in a great reduction in S. japonicum infection in humans, bovines and snails. Since 2007, no acute infection was detected, and no schistosomiasis cases or infected bovines were identified since 2012. In addition, the snail habitats reduced by 62.39% in 2014 as compared to that in 2005, and no S. japonicum infection was identified in snails since 2007. By 2014, 88.9% of the endemic counties achieved the transmission interruption of schistosomiasis and transmission control of schistosmiasis was achieved in the whole province in 2008.

Conclusion

The government-directed and multi-department integrated strategy is effective for interrupting the transmission of schistosomiasis in the mountainous and hilly regions of China.

[Schistosomiasis control progress and endemic situation in Sichuan Province]

OBJECTIVE

To understand the schistosomiasis control progress and endemic situation, so as to provide the evidence for formulating the strategy of schistosomiasis elimination in Sichuan Province.

METHODS

The schistosomiasis history data, working reports of schistosomiasis prevention and control, schistosomiasis surveillance data, and data of schistosomiasis prevention and control capacity were collected and analyzed for the schistosomiasis control progress and epidemic situation in Sichuan Province from 2004 to 2015.

RESULTS

There were 63 schistosomiasis endemic districts in 11 cities in Sichuan Province, and the standard of schistosomiasis transmission interruption was achieved in the whole province in 2015. Currently, the area with Oncomelania hupensis snails was 2 537.54 hm², and there were 1 769 advanced schistosomiasis patients. From 2004 to 2015, the accumulated survey area with snails was 433 065.80 hm², and the area of snail control by molluscicides was 251 259 hm². There were 26.017 144 million person-times of schistosomiasis blood tests and 7.89 million person-times of chemotherapy. There were 1.276 117 million head-times of cattle that received the schistosomiasis examinations. The schistosomiasis patients and livestock and the area with snails were decreased year by year. Since 2010, there were no local schistosome-infected residents and livestock and since 2004, there were no schistosome-infected snails. However, in some area, the professional personnel were less, the technology and hardware lagged behind, and the schistosomiasis prevention and control capacity was weak.

CONCLUSIONS

Sichuan Province achieved the standard of schistosomiasis transmission interruption in 2015. In the future, the comprehensive schistosomiasis prevention and control strategy still should be strengthened, including the promotion of schistosomiasis prevention and control capacity, establishment of sensitive early-warning surveillance system, and implementation of accurate schistosomiasis prevention and control, in order to consolidate the control achievements and realize the aim of schistosomiasis elimination as soon as possible.

[Surveillance on schistosomiasis after its transmission interruption in Baoying County, Jiangsu Province]

OBJECTIVE

To understand the endemic situation of schistosomiasis after its transmission interruption in Baoying County, so as to provide the evidence for adjusting the prevention and control strategy.

METHODS

The data of schistosomiasis surveillance in Baoying County from 1988 to 2015 were collected and retrospectively analyzed.

RESULTS

The schistosomiasis surveillance has been established since it was interrupted in Baoying County in 1987. The total surveyed area with Oncomelania hupensis snails was 21 269.95 hm², but no living snails were found. The number of schistosomiasis examinations of residents was 163 196 person-times, and 270 person-times were positive in serum test, 26 person-times were positive in stool test. No positive cases were found since 1997. The number of schistosomiasis tests of livestock was 2 180 cattle-times but no infection was found.

CONCLUSIONS

No schistosome infected snails or livestock are founded in Baoying County for last 28 years, and no patients are founded for last 11 years. The effect of schistosomiasis control is steady.

[Status and challenges for schistosomiasis in transmission-interrupted areas in Jiangxi Province]

This report analyzes the status of schistosomiasis epidemic, surveillance and challenges in transmission-interrupted areas of Jiangxi Province. There are 24 schistosomiasis transmission interrupted counties (cities, districts) among 39 endemic counties (cities, districts). Among the 24 counties, there are 6 counties with Oncomelania hupensis snails and 461 villages endemic, with 1.29 million residents. Since 2009, there have not been acute and chronic cases of schistosomiasis and all the patients are historical advanced schistosomiasis cases. The area with snail habitats is 37.02 hm². Since 2015, the schistosomiasis surveillance has covered the entire transmission interrupted areas. However, there are still many challenges, such as endemic instability, weak surveillance capacity, lack of surveillance awareness and other issues. Towards the schistosomiasis elimination, the surveillance should be based on the snail monitoring mainly, supplemented by the mobile population monitoring, and in addition, the capacity building, standardized report of endemic, and snail habitat reform should also be further strengthened.

[Schistosomiasis surveillance after interruption of schistosomiasis transmission in Xiuzhou District, Jiaxing City]

OBJECTIVE

To analyze the endemic situation of schistosomiasis after its interruption of transmission in Xiuzhou District, Jiaxing City, Zhejiang Province, so as to provide the references for future surveillance work.

METHODS

The data of schistosomiasis and Oncomelania hupensis snails in Xiuzhou District were collected and analyzed statistically.

RESULTS

From 1994 to 2015, totally 975 village-times were investigated for O. hupensis snails, and the accumulated area of 4 385.31 hm² was surveyed. Twenty former snail sites were reoccurring, with an area of 32.61 hm². An area of 57.71 hm² was supplied with snail eradication measures. Totally 11 941 snails were dissected and no schistosome infected snails were found. The serum and stool tests were performed to 221 794 and 3 731 residents respectively, and no local infection cases but four imported cases were found.

CONCLUSIONS

The endemic situation of schistosomiasis in Xiuzhou District is stable after the transmission was interrupted. However, there are imported schistosomiasis cases, and therefore, the prevention of imported infection source is the focus of surveillance work.