Snail Monitoring Research Articles

Unmanned Aerial Vehicle-Based Techniques for Monitoring and Prevention of Invasive Apple Snails (Pomacea canaliculata) in Rice Paddy Fields

The destructive impact of invasive apple snail (Pomacea canaliculata) on young rice seedlings has garnered global attention, particularly in warm regions where rice production occurs. The preventative application of insecticide, particularly in areas with young rice seedlings and water depths exceeding 4 cm, has proven effective in mitigating this damage. In line with this recommendation, our study investigates the efficacy of site-specific drone-based insecticide applications to mitigate snail damage in rice paddies. These site-specific drone applications were strategically executed as directed by a highly accurate prescription map indicating the required insecticide quantity at specific locations. The prescription map was automatically generated through an advanced data processing program that used the aerial images acquired by a Real-Time Kinematic (RTK)-Unmanned Aerial Vehicle (UAV) as the input. Criteria were established to select the treatment locations; a value of below 4 cm from the top 95% percentile in the histogram of ground elevation data was used as a threshold to identify areas with a high-density of snail damage. The results demonstrated reductions in both the rates of rice damage and chemical usage following site-specific drone applications compared with the control fields. The findings in this study contribute to the advancement of effective site-specific pest control in precision agriculture.

Exploring freshwater snail diversity and community structure in china's largest lake using eDNA technology

Freshwater snails are a crucial benthic animal group that plays a pivotal role in algae regulation and ecosystems while serving as intermediate hosts for certain parasites. Environmental DNA (eDNA) technology offers numerous advantages for biodiversity assessment. However, the utilization of eDNA techniques for freshwater snail monitoring remains limited. In this study, we screened primers for assessing freshwater snail diversity using eDNA technology and constructed a comprehensive database for Poyang Lake. Using eDNA technology, a total of 21 species of snails were detected in Poyang Lake, while traditional methods detected only 11 species. Notably, all species collected by traditional methods were also detected by eDNA technology. Additionally, environmental DNA methods detected the invasive snail Pomacea canaliculata, while traditional methods did not. In this study, eleven intermediate host snail species for parasitic disease were identified using eDNA methods, while six were detected through traditional sampling techniques. The eDNA metabarcoding analysis showed that the α and β diversity levels of snails in Poyang Lake did not vary significantly, indicating that results obtained by eDNA sampling are not influenced by the season in which samples were collected. The correlation analysis between the community structure of snails and environmental factors in Poyang Lake revealed significant impacts of total nitrogen, chlorophyll a, water depth, and water temperature on the snail community structure. These results confirm that eDNA technology can be exploited to monitor freshwater snail biodiversity.

Oncomelania hupensis Distribution and Schistosomiasis Transmission Risk in Different Environments under Field Conditions.

The goal of schistosomiasis prevention and control in China is shifting from transmission interruption to elimination. However, the area inhabited by the intermediate host, the snail Oncomelania hupensis, has not changed much in recent years. Different environmental types have different impacts on snail breeding, and understanding these differences is conducive to improving the efficiency of snail monitoring and control and to saving resources. Based on previous epidemiological data, we selected 199 villages in 2020 and 269 villages in 2021 from transmission control, transmission interruption, and elimination areas of snail breeding. Snail surveys were conducted in selected villages using systematic sampling and/or environmental sampling methods in six types of snail-breeding environments (canals, ponds, paddy fields, dry lands, bottomlands, and undefined environments). All live snails collected from the field were evaluated for Schistosoma japonicum infection using the microscopic dissection method, and a subsample of snails was subjected to loop-mediated isothermal amplification (LAMP) to assess the presence of S. japonicum infection. Snail distribution data and infection rate and nucleic acid positive rate of schistosomes in snails were calculated and analyzed. The 2-year survey covered 29,493 ha of the environment, in which 12,313 ha of snail habitats were detected. In total, 51.16 ha of new snail habitats and 107.76 ha of re-emergent snail habitats were identified during the survey. The occurrence rate of snails in canals (10.04%, 95% CI: 9.88-10.20%) and undefined environments (20.66%, 95% CI: 19.64-21.67%) was relatively high in 2020, and the density of snails in bottomlands (0.39, 95% CI: 0.28-0.50) and undefined environments (0.43, 95% CI: 0.14-1.60) was relatively high in 2021. Of the 227,355 live snails collected in this study, none were S. japonicum-positive as determined by microscopy. Of the 20,131 pooled samples, however, 5 were S. japonicum-positive based on LAMP analysis, and they were distributed in three environmental types: 3 in bottomland, 1 in dry land, and 1 in a canal. The bottomland environment has a high risk of schistosomiasis transmission because it contains a large area of newly emerging and re-emerging snail habitats, and it also had the most breeding snails infected with S. japonicum. Thus, this habitat type should be the key target for snail monitoring and early warning and for the prevention and control of schistosomiasis.

Population Genetics of Oncomelania hupensis Snails from New-Emerging Snail Habitats in a Currently Schistosoma japonicum Non-Endemic Area.

Schistosomiasis is still one of the most significant neglected tropical diseases worldwide, and China is endemic for Schistosoma japonicum. With its great achievement in schistosomiasis control, the government of China has set the goal to eliminate the parasitic disease at the country level by 2030. However, one major challenge is the remaining huge areas of habitats for the intermediate host Oncomelania hupensis. This is further exacerbated by an increasing number of new emerging snail habitats reported each year. Therefore, population genetics on snails in such areas will be useful in evaluation of snail control effect and/or dispersal. We then sampled snails from new emerging habitats in Taicang of Jiangsu, China, a currently S. japonicum non-endemic area from 2014 to 2017, and performed population genetic analyses based on nine microsatellites. Results showed that all snail populations had low genetic diversity, and most genetic variations originated from within snail populations. The estimated effective population size for the 2015 population was infinitive. All snails could be separated into two clusters, and further DIYABC analysis revealed that both the 2016 and the 2017 populations may derive from the 2015, indicating that the 2017 population must have been missed in the field survey performed in 2016. These findings may have implications in development of more practical guidelines for snail monitoring and control.

The Potential of Citizen-Driven Monitoring of Freshwater Snails in Schistosomiasis Research

Schistosomiasis is a tropical parasitic disease affecting more than 200 million people worldwide, predominantly in Africa. The World Health Organization recently highlighted the importance of targeted control of the freshwater snails acting as intermediate hosts for the parasites causing schistosomiasis. However, because of a shortage of trained experts and resources, detailed information on spatiotemporal snail distributions, which is needed for targeted control measures, is often missing. We explore the potential of citizen science to build these much-needed datasets through fine-grained, frequent snail sampling. We trained a network of 25 citizen scientists to weekly report on snail host abundances in 77 predefined water contact sites in and around Lake Albert (western Uganda). Snail abundance, together with marked GPS locations, water chemistry parameters, and photographs of the identified snails are recorded and submitted using the freely available mobile phone application KoBoToolbox. Trained researchers then engage in remote, semi-automatic validation of the submissions, after which there is an opportunity to provide targeted feedback to the citizen scientists. Five months after the operationalisation of the network, a total of 570 reports were submitted and personalized feedback was given, resulting in lasting improvements in subsequent reporting and snail genus identification. The preliminary results show the possibility of citizen science to independently obtain reliable data on the presence of schistosome snail hosts. We therefore argue that citizen-driven monitoring on a high spatiotemporal resolution could help to generate the much-needed data to support local targeted snail control measures in remote and/or resource-limited environments.

Evaluation of the effect of the water-saving irrigation project on Oncomelania hupensis control in hilly regions of Yixing City, Jiangsu Province

To evaluate the effect of the water-saving irrigation project on Oncomelania hupensis snail control in hilly regions of Yixing City, Jiangsu Province. A retrospective survey combined with cross-sectional investigation was employed. The implementation of the water-saving irrigation development project in Yixing City from 2005 to 2007 was retrospectively collected, and the snail status was collected in regions where the water-saving irrigation project was located and the project-affected regions from 2003 to 2018, to examine the effect of the project on snail control. In addition, a cross-sectional survey was performed to investigate the destruction of the water-saving irrigation project in 2018. A total of 22 water-saving irrigation projects were implemented in 5 townships in hilly regions of Yixing City from 2005 to 2007, where snail habitats were treated covering 266.97 hm2. Before the implementation of the project from 2003 to 2006, cumulative 47.87 hm2 snail habitats were detected in regions where the project was located, and no snails were found in regions where the project was located from the implementation of the project in 2006 to 2018. However, a few snails were found in the project-affected regions in 2017 and 2018. In addition, there were problems found in the later-stage maintenance and management of the project. The water-saving irrigation projects shows a high efficiency on snail control in hilly regions of Yixing City. The later-stage maintenance of the project and monitoring of snails remain to be intensified to enhance the snail control efficiency of the water-saving irrigation project.

SIPUT PROSOBRANCHIA (GASTROPODA, MOLUSKA) PADA RATAAN TERUMBU KARANG DI TELUK MANADO

Molluscs are marine organisms that do not have a backbone, these organisms are associated with coral reefs. This research was conducted with the aim of describing the density and diversity of Prosobranchia snails’ species on coral reef flats. By applying the belt transect method, the results show that the density of the four Mokupa stations has a relatively high density between Tongkeina, Malalayang and Bulo. While for species diversity, Mokupa and Bulo had the highest value than Tongkeina and Malalayang. According to the results of the belt transect method, is the concluded that stations close to people’s homes have the lowest density and species diversity values, this factor is influenced by anthropogenic activities or human activities. Therefore, it is recommended that there be monitoring of snails on coral reefs, especially reef flattening in order to provide information about Prosobranchia snails.Keywords: Prosobranchia, Density, diversity, belt transects, Reef Flats

Snail-Related Contributions from the Schistosomiasis Consortium for Operational Research and Evaluation Program Including Xenomonitoring, Focal Mollusciciding, Biological Control, and Modeling.

.The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) was created in 2008 to answer questions of importance to program managers working to reduce the burden of schistosomiasis in Africa. In the past, intermediate host snail monitoring and control was an important part of integrated schistosomiasis control. However, in Africa, efforts to control snails have declined dramatically over the last 30 years. A resurgence of interest in the control of snails has been prompted by the realization, backed by a World Health Assembly resolution (WHA65.21), that mass drug administration alone may be insufficient to achieve schistosomiasis elimination. SCORE has supported work on snail identification and mapping and investigated how xenomonitoring techniques can aid in the identification of infected snails and thereby identify potential transmission areas. Focal mollusciciding with niclosamide was undertaken in Zanzibar and Côte d’Ivoire as a part of elimination studies. Two studies involving biological control of snails were conducted: one explored the association of freshwater riverine prawns and snail hosts in Côte d’Ivoire and the other assessed the current distribution of Procambarus clarkii, the invasive Louisiana red swamp crayfish, in Kenya and its association with snail hosts and schistosomiasis transmission. SCORE also supported modeling studies on the importance of snail control in achieving elimination and a meta-analysis of the impact of molluscicide-based snail control programs on human schistosomiasis prevalence and incidence. SCORE’s snail control studies contributed to increased investment in building capacity, and specimens collected during SCORE research deposited in the Schistosomiasis Collections at the Natural History Museum (SCAN) will provide a valuable resource for the years to come.

Endemic situation of schistosomiasis in Jiangshan City from 2008 to 2018

To analyze the endemic situation of schistosomiasis in Jiangshan City from 2008 to 2018, so as to provide evidence for formulating the future control strategy. The data regarding Oncomelania snail survey and control, schistosomiasis examinations and environmental improvements were collected in Jiangshan City from 2008 to 2018. The changes in snail status and morbidity due to Schistosoma japonicum infections were analyzed to assess the effectiveness of comprehensive schistosomiasis control. From 2008 to 2018, a total of 61 220 person-times were examined for S. japonicum infections in Jiangshan City, and the overall seroprevalence of S. japonicum infections was 0.56% (343/61 220); however, no egg-positives were detected. Among 4 231 cattle screened for S. japonicum infections using blood tests in Jiangshan City during the period from 2008 to 2018, 12 were sero-positive, with sero-prevalence of 0.28% (12/4 231), and no egg-positives were identified. There were 422 snail habitats identified in Jiangshan City during the study period, covering an area of 46.915 hm2, and among the 31 686 snails dissected, no S. japonicum infections were detected. An area of 3 625.492 hm2 snail habitats were subjected to repeated snail control and 11 settings were given environmental improvements, covering snail habitats of 17.880 hm2 and historical snail habitats of 204.380 hm2. Following the implementation of environmental improvements-based comprehensive schistosomiasis control, the endemic situation of schistosomiasis is stable in Jiangshan City; however, there is still a risk of snail importation and re-emerging schistosomiasis. Therefore, the monitoring of snails and morbidity due to S. japonicum infections should be intensified in the city.

Administrative village-based spatial distribution specificity of Oncomelania hupensis and its relationship with water systems in Hubei Province

To investigate the spatial distribution of Oncomelania hupensis snail habitats at the administrative village scale in schistosomiasis-endemic areas of Hubei Province, so as to provide scientific bases for precise control of O. hupensis snails in the province. Data regarding snail distribution at the village level in Hubei Province in 2017 were collected to create a spatial analysis database of snail distribution in Hubei Province. The spatial aggregations of O. hupensis distribution were analyzed using Moran's I index and Local Moran's I index. In addition, the distances from schistosomiasis-endemic villages to the Yangtze River were captured using the software ArcGIS 13.0, and their correlations with area of snail habitats were examined with the Spearman correlation method. O. hupensis snails were mainly distributed in 5 450 endemic villages from 63 counties of 13 cities in Hubei Province in 2017. The global spatial autocorrelation analysis showed spatial aggregations in the areas of historically accumulated snail habitats, current areas of snail habitats, areas of snail habitats outside the embankment and snail habitats inside the embankment (all Z Scores > 0, all P values < 0.05), and no spatial aggregation was seen in the areas of snail habitats in hilly areas (Z Score > 0, P > 0.05). There were four types of spatial distribution of historically accumulated areas of snail habitats, areas of current snail habitats, areas of snail habitats outside the embankment and snail habitats inside the embankment, including the high-high type (H-H type), high-low type (H-L type), low-high type (L-H type) and random distribution type, and a high percentage of the H-H type was found. There were 340, 125 and 110 endemic villages with the H-H type of areas of historically accumulated snail habitats, current areas of snail habitats and areas of snail habitats outside the embankment, and these villages were mainly concentrated in Wuhan and Jingzhou cities, with almost consistent spatial aggregation locations. There were 319 endemic villages with the H-H type of distribution of snail habitats inside the embankment, which were mainly distributed in Jingzhou, Xiaogan and Huangshi cities. In addition, the areas of historically accumulated snail habitats, current areas of snail habitats and areas of snail habitats outside the embankment negatively correlated with the distance from the endemic villages to the Yangtze River (r = -0.094, P < 0.01; r = -0.225, P < 0.01; r = -0.177, P < 0.01). The clustering areas of snail habitats along the Yangtze River Basin, notably the villages near the Yangtze River are key regions for snail monitoring and control in Hubei Province.

Construction and application of the surveillance system for schistosomiasis transmission risk in Sichuan Province

To build a schistosomiasis transmission risk surveillance system in Sichuan Province, so as to provide technical support for facilitating the progress towards schistosomiasis elimination in the province. The surveillance sites for schistosomiasis transmission risk were assigned in 63 endemic counties (districts) of 11 cities (prefectures) in Sichuan Province. During the period from 2015 through 2018, wild feces contamination, the sources of Schistosoma japonicum infections (fever patients, livestock and wild animals), water infectivity in key settings, snail distribution in key settings, and snail breeding risk (snail importation and spread, floating debris carrying snails and snail breeding in ecological wetlands) were monitored in the surveillance sites. From 2015 to 2018, a total of 1 636 wild faces were detected in Sichuan Province, and 3 faces were positive for S. japonicum, with a 0.18% positive rate; among 3 995 livestock and 59 wild mice monitored, no S. japonicum infection was detected. A total of 49 414 fever patients were monitored in 2018, and 493 were seropositive for S. japonicum infection; then, 445 seropositives were subjected to stool examinations, and no egg-positives were found. From 2010 to 2018, a total of 93 sentinel sites were assigned, and 3 994 sentinel mice were placed for monitoring the water infectivity, with one S. japonicum-infected mouse detected. Between 2015 and 2018, a total of 4 156 key settings were investigated covering an area of 1 998.46 hm2, and 668 settings were detected with snails (16.07%), covering an area of 193.26 hm2; 497 suspected settings with a likelihood of snail importation with plant introduction were monitored from 2017 to 2018, and 65 settings with snails were found with 2 673 snails captured; 593 sites were assigned to collect the floating debris from 2017 to 2018, and 9 191.39 kg floating debris were collected with 186 snails captured; 4 wetlands were monitored for the risk of schistosomiasis transmission from 2013 to 2015, and snail breeding was found in 2 wetlands. No S. japonicum infection was identified in snails captured from all surveillance sites. A sensitive and effective schistosomiasis transmission risk surveillance system has been successfully established in Sichuan Province. There is still a risk of schistosomiasis transmission risk in local areas of Sichuan Province. Therefore, the integrated schistosomiasis control measures with emphasis on the control of the source of S. japonicum infections should be further intensified, and snail monitoring and control and monitoring and control of schistosomiasis in wetlands should be also intensified.

Investigation on current distribution of Oncomelania snails in schistosomiasis-endemic areas of Sichuan Province

To understand the current distribution of Oncomelania snails in Sichuan Province, so as to provide scientific evidence for formulating the schistosomiasis elimination strategy and implementing the precision schistosomiasis control measures in the province. According to the National Scheme on Oncomelania hupensis Snails in China and the Scheme on Oncomelania hupensis Snails in Sichuan Province, snail surveys were performed in current snail habitats, historical snail habitats and suspected snail habitats using systematic sampling in Sichuan Province from 2016 to 2017, and the survey results were analyzed. From 2016 to 2017, a total of 88 346 settings were surveyed in schistosomiasis-endemic areas of Sichuan Province, and 19 314 settings were detected with snails, covering an area of 4 829.25 hm2, with no Schistosoma japonicum infection identified in snails. A total of 3 017 915 frames were investigated in Sichuan Province, and 1 041 417 frames were found to have living snails, with totally 1 791 115 living snails captured. The mean density of living snails was 0.59 snails/0.1 m2, and the mean percentage of frames with living snails was 34.51% in Sichuan Province. The current snail habitats were mainly distributed in 1 704 villages, 377 townships, 54 counties (districts) of 9 cities (prefectures) across the schistosomiasis-endemic areas of Sichuan Province. Snail habitats were mainly found in ditches (70.22%), and weeds were the predominant vegetation in snail habitats (66.45%). Snails were firstly discovered in Sichuan Province in 1913, and S. japonicum-infected snails were firstly identified in 1956, with the latest identification of S. japonicum-infected snails in 2008. There are many settings suitable for snail breeding in Sichuan Province, and snail monitoring and control should be intensified in the future.

Integrating laboratory and field studies to assess impacts of discharge from a uranium mine and validate a water quality guideline value for magnesium.

Magnesium (Mg) is a primary contaminant in mine water discharges from the Ranger Uranium Mine (north Australia). Site-specific water quality guideline values (WQGVs) for Mg have been derived from laboratory and field studies. Contaminated groundwater with elevated electrical conductivity and metals (Mg, Mn, U, SO4 , and Ca) was detected flowing from the mine site into adjacent surface waters. This provided an opportunity to investigate the protectiveness of the Mg WQGV by conducting an integrated laboratory and field study. A direct toxicity assessment (DTA) of the groundwater was conducted with local tropical freshwater species: duckweed (Lemna aequinoctialis), green hydra (Hydra viridissima), and the aquatic snail Amerianna cumingi. An in situ toxicity assessment was carried out in the creek receiving diluted groundwater by use of the same species of snail, to aid interpretation of laboratory-derived data. The toxicity of the contaminated groundwater was higher than Mg-only toxicity testing for H. viridissima, with other elevated metals and major ions contributing to toxicity. However, for duckweed and snail, the contaminated groundwater was less toxic than the Mg-only testing. In situ snail monitoring supported laboratory exposures, showing no effect on reproduction of A. cumingi exposed to an average of approximately 5 mg/L Mg; however, a very small effect was noted closer to the groundwater source, probably associated with other contaminants. The minimal toxicity observed for L. aequinoctialis and A. cumingi, despite the elevated Mg, can be explained by the high calcium (Ca) concentration of the water and the potential amelioration of metal toxicity. The extent of Ca amelioration of Mg toxicity was organism dependent. This study affirms the proposed environmental rehabilitation standard of 3 mg/L Mg for surface waters with a Ca concentration typical of water from this mine site. Integr Environ Assess Manag 2019;15:64-76. © 2018 SETAC.

Endemic situation of schistosomiasis in surveillance sites of Jingzhou City, 2017

To grasp the endemic situation of schistosomiasis in Jingzhou City in 2017, so as to provide the evidence for formulating prevention strategies. According to the requirements of National Schistosomiasis Surveillance Program (2014), Hubei Schistosomiasis Surveillance Program (2015) and Jingzhou Schistosomiasis Surveillance Program, the local population infection monitoring, mobile population infection monitoring, livestock disease monitoring, snail monitoring, and wild manure monitoring were carried out at 71 monitoring sites throughout the city. Among the 71 surveillance sites, 44 118 local residents received the indirect hemagglutination test (IHA) for schistosomiasis and 1 925 persons were positive, with the positive rate of 4.36%, However, no stool examination positive cases were found. Totally 2 175 mobile people received the IHA for schistosomiasis and 93 persons were positive, with the positive rate of 4.28%, but no stool examination positive cases were found. A total of 1 937 head of cattle received the stool examination for schistosome infection, but no positives were found. Totally 1 302 Oncomelania hupensis habitats were found in 69 surveillance sites, with 1 923.64 hm2 area with snails. Totally 348 756 frames were surveyed, and the occurrence rate of snails was 17.19%. A total of 142 494 living snails were captured, with the average density of 0.41 snail/0.1 m2. No schistosome-infected snails were found. Totally 596 cases of wild manure were picked up in 41 environments with snails among 23 surveillance sites, but schistosome infested wild manure was not found. In 2017, the level of schistosomiasis epidemic was very low in Jingzhou City. However, the risk of epidemic rebound still exists, and therefore, it is necessary to strengthen the monitoring work to further consolidate the achievements of schistosomiasis control.

Implementation of Oncomelania hupensis monitoring system based on Baidu Map

To construct the Oncomelania hupensis snail monitoring system based on the Baidu Map. The environmental basic information about historical snail environment and existing snail environment, etc. was collected with the monitoring data about different kinds of O. hupensis snails, and then the O. hupensis snail monitoring system was built. Geographic Information System (GIS) and the electronic fence technology and Application Program Interface (API) were applied to set up the electronic fence of the snail surveillance environments, and the electronic fence was connected to the database of the snail surveillance. The O. hupensis snail monitoring system based on the Baidu Map were built up, including three modules of O. hupensis Snail Monitoring Environmental Database, Dynamic Monitoring Platform and Electronic Map. The information about monitoring O. hupensis snails could be obtained through the computer and smartphone simultaneously. The O. hupensis snail monitoring system, which is based on Baidu Map, is a visible platform to follow the process of snailsearching and molluscaciding.

Application of electronic fence technology based on GIS in Oncomelania hupensis snail monitoring

To study the application of Geographic Information System (GIS) electronic fence technique in Oncomelania hupensis snail monitoring. The electronic fence was set around the history and existing snail environments in the electronic map, the information about snail monitoring and controlling was linked to the electronic fence, and the snail monitoring information system was established on these bases. The monitoring information was input through the computer and smart phone. The electronic fence around the history and existing snail environments was set in the electronic map (Baidu map), and the snail monitoring information system and smart phone APP were established. The monitoring information was input and upload real-time, and the snail monitoring information was demonstrated in real time on Baidu map. By using the electronic fence technology based on GIS, the unique "environment electronic archives" for each snail monitoring environment can be established in the electronic map, and real-time, dynamic monitoring and visual management can be realized.

Oncomelania hupensis status monitoring in Changzhou City, Jiangsu Province from 2013 to 2016

Objective To analyze the Oncomelania hupensis snail distribution and the changes of snail situation in Changzhou City from 2013 to 2016, so as to provide the evidence for formulating the schistosomiasis prevention and control interventions. Methods The data of snail monitoring in Changzhou City from 2013 to 2016 were collected and statistically analyzed. Results The total area with snails was 40.17 hm2 and the newly discovered area was 30.63 hm2 in Changzhou City from 2013 to 2016. In the four years, 3 454 snails were dissected, and no schistosome infected snails were found. There were totally 51 spots with snails, and the areas with snails of different types of marshland, inland and mountain were 12.13 (30.19%), 25.54 hm2 (63.57%) and 2.51 hm2 (6.24%), respectively. In the newly discovered snail environment, the areas of types of marshland and inland were 8.00 hm2 (26.12%) and 22.63 hm2 (73.88%), respectively. The main causes for snail existence were external input and adjacent diffusion. In the past four years, the total snail control area with molluscicides was 71.74 hm2, the consolidated snail control area with molluscicides was 155.15 hm2, and the total environmental modification areas in the current snail spots and historic snail spots were 15.90 hm2 and 11.30 hm2 respectively. Conclusion The diffusion of snails in inland rivers is the key of the newly discovered snail areas in Changzhou City in recent years, and the snail monitoring and control measures should be strengthened in the future.

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.

A Refinement of an International Standard Method (ISO/TS 15216–2:2013) to Allow Extraction and Concentration of Human Enteric Viruses from Tissues of Edible Snail Species

In the recent years, a revival in interest in snail meat consumption has promoted a rapid development of snail farming systems to cover an increasing consumer demand and to protect the free-living snail population. Snail meat, like other types of food intended for human consumption, should be free from any microbiological hazards before being placed on the market. Snail meat may contain bacteria, but little is known about the possibility of contamination with human enteric viruses. Therefore, to test snail tissues for viruses, a suitable virus detection method is needed. Up to now, many methods for virus extraction and concentration from molluscan shellfish have been published, but only one has been adopted as an international standard procedure. In this study, a refinement of an ISO method (ISO/TS 15216–2:2013) was conducted to make it suitable for processing of edible snail tissues. The digestive glands from three edible snail species (Helix pomatia, Cornu aspersum maxima, Cornu aspersum aspersum) were used as samples, and method performance was assessed on the basis of murine norovirus RNA detection in spiked samples using a one-step real-time reverse transcription-PCR. The mean percentage of virus recovery from tissues of C. a. maxima was 5.71 %, 0.31 % for C. a. aspersum and 1.28 % for edible snail. As demonstrated here, this method was successfully applied for virus detection in snail samples, and its use can be recommended in monitoring of snails for virus contamination.

Differentiating Schistosoma haematobium from Schistosoma magrebowiei and other closely related schistosomes by polymerase chain reaction amplification of a species specific mitochondrial gene.

Introduction:Schistosoma haematobium infection afflicts about 150 million people in 53 countries in Africa and the Middle East. In many endemic areas, S. haematobium is sympatric with Schistosoma bovis, Schistosoma mattheei, Schistosoma curassoni, Schistosoma intercalatum and Schistosoma magrebowiei, its closely related species. In addition, they also develop in the same intermediate snail hosts. Since these schistosome species often infect snails inhabiting the same bodies of water, examining cercariae or infected snails for estimating transmission of S. haematobium is always confounded by the need to differentially identify S. haematobium from these other species. Recently, differentiating S. haematobium by polymerase chain reaction (PCR) from S. bovis, S. mattheei, S. curassoni and S. intercalatum, but not from S. magrebowiei was reported. However, to be able to evaluate residual S. haematobium transmission after control interventions in areas where S. haematobium may be sympatric with S. magrebowiei, a differential tool for accurate monitoring of infected snails is needed.Materials and Methods:Thus in this study, we developed a new PCR assay using a pair of primers, ShND-1/ShND-2, to amplify a target sequence of 1117 bp (GenBank accession number KF834975) from S. haematobium mitochondrion complete genome (GenBank accession number DQ157222). Sensitivity of the assay was determined by PCR amplification of different concentrations of S. haematobium gDNA serially diluted from 10ng to 0.1pg. For assay specificity, different concentrations of gDNA from S. haematobium and the other schistosome species, 20 positive urine samples and five controls as well as 20 infected snails were subjected to PCR amplification, while some of the PCR products were sequenced.Results:The assay detected up to 1pg of S. haematobium gDNA, while a differential identification of S. haematobium DNA content from other closely related species was achieved when applied to urine and naturally infected snails. When a protein-protein blast search was carried out using Blastp, the amplified sequence was found to encode a protein that shows a 100% similarity with S. haematobium nicotinamide adenine dinucleotide dehydrogenase subunit 3 (GenBank accession number YP_626524.1).Conclusion:The PCR assay was sensitive, specific and was able to successfully differentiate S. haematobium from S. magrebowiei, in addition to its other closely related animal infective schistosome species.