The golden apple snail Pomacea canaliculata is an invasive pest that causes extensive damage to agricultural production. P. canaliculata is also an intermediate host of Angiostrongylus cantonensis, which causes human eosinophilic meningitis. In this study, the molluscicidal activity and safety profile of a novel molluscicide PBQ [1-(4-chlorophenyl)-3-(pyridin-3-yl)urea] were evaluated. PBQ exhibited strong molluscicidal potency against adult and juvenile snails (LC 50 values of 0.39 and 0.07 mg/L, respectively). In field trials, PBQ killed 99.42% of the snails at 0.25 g a.i./m 2 . An acute toxicity test in rats demonstrated that PBQ is a generally nonhazardous chemical. PBQ is also generally safe for nontarget organisms including Brachydanio rerio, Daphnia magna, and Apis mellifera L. Transcriptomics analysis revealed that PBQ had a significant impact on the carbohydrate and lipid metabolism pathways, which provided insights into its molluscicidal mechanism. These results suggest that PBQ could be developed as an effective and safe molluscicide for P. canaliculata control.

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BackgroundThe prevalence of schistosomiasis remains a key public health issue in China. Jiangling County in Hubei Province is a typical lake and marshland endemic area. The pattern analysis of schistosomiasis prevalence in Jiangling County is of significant importance for promoting schistosomiasis surveillance and control in the similar endemic areas.MethodsThe dataset was constructed based on the annual schistosomiasis surveillance as well the socio-economic data in Jiangling County covering the years from 2009 to 2013. A village clustering method modified from the K-mean algorithm was used to identify different types of endemic villages. For these identified village clusters, a matrix-based predictive model was developed by means of exploring the one-step backward temporal correlation inference algorithm aiming to estimate the predicative correlations of schistosomiasis prevalence among different years. Field sampling of faeces from domestic animals, as an indicator of potential schistosomiasis prevalence, was carried out and the results were used to validate the results of proposed models and methods.ResultsThe prevalence of schistosomiasis in Jiangling County declined year by year. The total of 198 endemic villages in Jiangling County can be divided into four clusters with reference to the 5 years’ occurrences of schistosomiasis in human, cattle and snail populations. For each identified village cluster, a predictive matrix was generated to characterize the relationships of schistosomiasis prevalence with the historic infection level as well as their associated impact factors. Furthermore, the results of sampling faeces from the front field agreed with the results of the identified clusters of endemic villages.ConclusionThe results of village clusters and the predictive matrix can be regard as the basis to conduct targeted measures for schistosomiasis surveillance and control. Furthermore, the proposed models and methods can be modified to investigate the schistosomiasis prevalence in other regions as well as be used for investigating other parasitic diseases.Electronic supplementary materialThe online version of this article (doi:10.1186/s40249-017-0303-5) contains supplementary material, which is available to authorized users.

The molluscicidal activity of a novel molluscicide (niclosamidate) was evaluated in field trials against Oncomelania hupensis, the intermediate host of Schistosoma japonicum. The environmental safety of niclosamidate for local fishes was also studied under field conditions. The results showed that, at the dosages of 8.0 g/m and 4.0 g/m, niclosamidate exhibits highly potent molluscicidal activity in the spraying and immersion trials, resulting in mortality rates of up to 81.8 and 72.7%, respectively. Its performance seems to be target-specific, with good molluscicidal ability observed for Oncomelania hupensis snails, but very low toxicity for local fishes and other aquatic organisms. The results suggest that niclosamidate can be used as an alternative molluscicide for snail control, which would be particularly applicable in semi-commercial or commercial aquaculture ponds.

Background Schistosomiasis japonica remains an important public health concern due to its potential to cause severe outcomes and long-term sequelae. An integrated control strategy implemented in the Peoples’ Republic of China has been shown to be effective to control or interrupt the transmission of schistosomiasis. The objective of this study is to estimate the disease burden of schistosomiasis and assess the cost-effectiveness of the integrated control strategy focused on different major interventions at three stages for schistosomiasis control in a lake setting, to provide reference for policy making or planning. Methods Annual cost data of schistosomiasis control during 2009–2019 were obtained from the control program implementers in Jiangling County, Hubei Province, China. Economic costs are provided in constant 2009 Chinese Yuan (CNY). Epidemiological data of schistosomiasis were collected from the Jiangling county station for schistosomiasis control. Disease burden of schistosomiasis was assessed by calculating years of life lost (YLLs) owing to premature death, years lived with disability (YLDs) and disability-adjusted life years (DALYs). DALYs were calculated as the sum of YLLs and YLDs. We then conducted a rudimentary cost-effectiveness analysis by determining the ratio by dividing the difference between the average cost of integrated control strategy at transmission control (2013–2016) or transmission interruption (2017–2019) and the average cost at stage of infection control (2009–2012) with the difference between the DALYs of schistosomiasis at different control stages. Descriptive statistics on the costs and DALYs were used in the analysis. Results The total economic costs for schistosomiasis control in Jiangling County from 2009 to 2019 were approximately CNY 606.88 million. The average annual economic costs for schistosomiasis prevention and control at stages of infection control (2009–2012), transmission control (2013–2016), and transmission interruption (2017–2019) were approximately CNY 41.98 million, CNY 90.19 million and CNY 26.06 million respectively. The overall disease burden caused by schistosomiasis presented a downward trend. Meanwhile, the disease burden of advanced cases showed an upward trend with the DALY increased from 943.72 to 1031.59 person-years. Most disease burden occurred in the age group over 45 years old (especially the elderly over 60 years old). Taking the infection control stage as the control, the incremental cost-effectiveness ratio of integrated control strategy was CNY 8505.5 per case averted, CNY 60 131.6 per DALY decreased at transmission control stage and CNY −2217.6 per case averted, CNY −18 116.0 per DALY decreased at transmission interruption stage. Conclusions The disease burden of schistosomiasis decreased significantly with the implementation of the integrated prevention and control strategy. Surveillance and management on elder population should be strengthened to decrease diseases burden. There remains a need for well-conducted studies that examine the long-term cost-effectiveness of the integrated control strategy for schistosomiasis. Graphic Abstarct