Oncomelania Hupensis Snail Control Research Articles

Field validation of different intervention modes for the potential transmission risk of schistosomiasis during post-transmission interruption phase.

Precision interventions have been proposed in transmission-interrupted areas to further reduce the potential transmission risk of schistosomiasis. This study aimed to evaluate the effects of different interventions modes for potential transmission risk control. Three groups of schistosomiasis-endemic villages were selected in Jiangling county, Hubei province. After baseline surveys in 2020, three intervention models were employed in 2021 and 2022. In Model 1, Oncomelania hupensis snail control in key settings and an integrated strategy with an emphasis on the infectious sources managing was employed. In Model 2, an integrated health education-led strategy with an emphasis on infectious source management was employed. In Model 3, only the integrated strategy with an emphasis on infectious source management was employed. The effects of the different intervention models were examined with multiple indicators after 2 years of intervention using the entropy-weighted technique for order of preference by similarity to ideal solution (TOPSIS), rank-sum ratio (RSR) and fuzzy combination model of entropy-weighted TOPSIS and RSR. Entropy-weighted TOPSIS modeling showed that the Ci values of Model 2 were 0.4434, 0.2759, and 0.3069 in the three pilot villages, Ci values were larger, with top comprehensive ranking. The results of the RSR method showed that the RSR values of Model 2 were 0.75, 0.708, and 0.736 in the three pilot villages, with top comprehensive ranking. The results from the fuzzy combination model of entropy-weighted TOPSIS and RSR showed that implementation of Model 2 resulted in the highest comprehensive ranking among the three models in the three pilot villages under Ci: RSR = 0.1: 0.9, Ci: RSR = 0.5: 0.5 and Ci: RSR = 0.9: 0.1. The integrated health education-led strategy with an emphasis on infectious source management was the optimal model to manage the risk of transmission of schistosomiasis during the post-transmission interruption phase.

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.

Endemic situation of schistosomiasis in People's Republic of China from 2010 to 2017

To understand the epidemic trend of schistosomiasis in China from 2010 to 2017 so as to provide the scientific evidence for schistosomiasis elimination. The information of schistosomiasis control nationwide from 2010 to 2017 was collected, including the endemic of population, status of livestock control, and Oncomelania hupensis snail control. Microsoft Excel was applied for datum management and analysis. From 2010 to 2017, the epidemic of schistosomiasis in China dropped significantly. The decreasing amplitude of estimated number of patients nationwide was 88.46%. Seventy-one acute schistosomiasis patients were reported and 12.68% (9/71) of them were imported. The decreasing rate of cultivated cattle was 50.09%, and the accumulative number of schistosome-infected cattle was 17 239, and the average positive rate of stool examinations decreased from 1.04% to 0.000 22%. The area with snails nationwide was 373 596.18 to 363 068.95 hm2, and the new detected area with snails was 46.71 to 1 346.73 hm2. The area with schistosome-infected snails was 171.68 hm2 in 2012 and it was 9.25 hm2 in 2013. In 72 key monitoring points of 7 endemic provinces, there were 17 schistosome positive points of water body in 2010 and 6 points in 2016. There were some high risk-factors related to schistosomiasis transmission including schisto-some-infected cattle, dogs, and field rats, and the field stools, and the pasture in the area with snails in schistosomiasis monitoring points. The endemic status of schistosomiasis in China has dropped significantly, and the transmission level is very low. However, the infectious source and risk factors in the endemic environments have not be eliminated. Therefore, the infectious source control, health education, snail control, and transmission monitoring should be strengthened, so as to promote the progress of schistosomiasis elimination.

Effect of cutting beach group on Oncomelania hupensis snail control in south of Shaobo Lake, Jiangsu Province

To evaluate the effect of Oncomelania hupensis snail control of cutting the beach group in the south of Shaobo Lake. The general situation of the project of cutting the beach was surveyed, and the snail distribution was surveyed and the results were compared before and after cutting the beach in the beach group. The area of cutting beach was 928.33 hm2, the cubic meter of earthwork was 1 717.00 m3, the area of dumping ground was 425.76 hm2, the beach surface elevation was 3.2 m after cutting the beach, and the beach surface was fallen to 1.0 m under the ordinary water level. The area with snails was 44.69 hm2 before cutting the beach in 2011 but the area with snails was 1.78 hm2 after cutting the beach in 2018. The area with remaining snails was declined by 96.02% in 2018 as compared with that in 2011, and surviving snails were distributed on the uncut beach face. In Shaobo Lake, the O. hupensis snail breeding environment is eliminated by raising or lowering the beach, so it is an effective measure of snail control in lake regions.

Evaluation of implementation effect of schistosomiasis control program in Jiangsu Province from 2010 to 2015

To evaluate the actual effect of the schistosomiasis control program in Jiangsu Province from 2010 to 2015. A total of 67 schistosomiasis-endemic counties in 10 cities were selected, and a combination of retrospective investigation and on-site investigation was adopted to collect and record the epidemic data of the counties from 2010 to 2015, and a retrospective survey database of epidemic situation was established. The effects of integrated control strategies with both Oncomelania hupensis snail control and infection source control were evaluated. From 2010 to 2015, 2 465 911 persons who lived in endemic areas were detected for schistosomiasis, with 16 974 positive cases of blood examinations, and 8 positive cases of fecal examinations. Totally 5 145 people with advanced schistosomiasis were treated and 40 460 people with the history of schistosome cercarial-infested water contact received the expanded chemotherapy. A total of 127 636 cattle raised in the endemic areas were detected, and 51 619 cattle (head-times) with the history of cercarial-infested water contact also received the expanded chemotherapy. The area with snails control by molluscicides was 18 604.84 hm2. By the end of 2015, schistosomeinfected snails had not been found and there was no zoological schistosome infection for 5 consecutive years, and in addition, there had been no acute schistosome-infected persons for 6 consecutive years in the whole province. The area with snails dropped to 1 977.18 hm2, with a decreasing rate of 55.24% compared with that in 2010. After the implementation of the plan for the prevention and control of schistosomiasis in Jiangsu Province (2010-2015), the prevention and control of schistosomiasis has achieved remarkable effects and realized the goal of the plan.

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

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

Thinking on Oncomelania hupensis snail control by comprehensive control measures combined with "a total of five-water treatment"

Oncomelania hupensis is the only intermediate host of Schistosoma japonicum, and it has a significant influence on the transmission, control and elimination of schistosomiasis. In 2016, Zhejiang Province passed the national united assessment of "maintaining the schistosomiasis elimination status"; however, there are still O. hupensis snails remained in the very complicated environments. The breeding and spread of O. hupensis snails can be controlled for a long time with the environmental modification by adapting to local circumstance and scientific development, which can reduce the potential risk of schistosomiasis transmission and promote the development of local economy and society. This paper analyzes the working conditions of schistosomiasis prevention and control in Zhejiang Province and gives some relevant suggestions on how to guarantee the maintenance of the schistosomiasis elimination status in Zhejiang Province by the environmental modification combined with "a total of five-water treatment", which can effectively condense the local snail breeding environments in key schistosomiasis endemic regions.

Strategy and effect of Oncomelania hupensis snail control in inside-embankment areas in Junshan District, Hunan Province from 1998 to 2017

To explore the strategy and countermeasures of Oncomelania hupensis snail control and evaluate the effect in inside-embankment areas of lake-type schistosomiasis endemic area, for providing the effective method for controlling and interrupting the schistosomiasis transmission. The data of schistosomiasis epidemic and its control and prevention were collected in Junshan District, Hunan Province, and the effect of snail control countermeasures were evaluated and the trend of indexes of snails was drafted in the inside-embankment areas of Junshan District, Hunan Province from 1998 to 2007. The area with snails in the inside embankment areas of Junshan District decreased by 98.43%, from 1 496.66 hm2 in 1998 to 23.48 hm2 in 2017. The occurrence rate and average density of of living snails decreased from 20.61% and 0.45 snail/0.1 m2 in 2003 to 2.06% and 0.03 snail/0.1 m2 in 2017. The highest area with schistosome infected snails was found in 2001 and the total area was 79.36 hm2, however, no infected snails were found since 2007. The total fiscal investment for schistosomiasis prevention and control was 398.857 million RMB in Junshan District, including molluscicide (81.770 9 million RMB) and environment reform (213.5 million RMB) respectively. The comprehensive measures, mainly including the combination of molluscicide and environment reform have gotten a significant effect in snail control and elimination in the inside-embankment areas, but the snail surveillance still need to be strengthened in the historic areas with snails.

Dynamic simulation analysis of effects of project of ditching for drain on Oncomelania hupensis snail control and flood prevention security in Dongting Lake region

To evaluate the effects of the project of ditching for drain on Oncomelania hupensis snail control and flood prevention security and explore the optimal engineering design plan in Dongting Lake region. A retrospective study was performed on the previous studies about the project of ditching for drain. The reference values of project indices were determined. The outside levee of Nanhu New Distinct of Yueyang City in Dongting Lake region was selected as the study area, and the cross section of marshland perpendicular to the center line of the levee was extracted to research. According to the situations of various water levels, a dynamic simulation was performed on the effect and security of the project of ditching for drain through the software FLAC3D. The retrospective study showed that the project would be effective when the relatively subsoil water level decreased by 0.35 m, and the soil water content decreased correspondingly. The dynamic simulation by FLAC3D showed that the minimum safe distances between transverse ditch 1, vertical ditch and levee toe should be 25 m and 13 m respectively. The digging depth of transverse ditch and vertical ditch should be 1.2 m and 1.0 m respectively. If the width of marshland in drought period was less than 500 m, one transverse ditch was efficient. Otherwise, more transverse ditches should be set with the intervals of 300 m. The project of ditching for drain is an effective ecological snail elimination method. Optimizing the digging depth of ditches and distances between transverse ditches, vertical ditch and levee toe will ensure the effects and security of the project.

Practice of engineering management and its effect on schistosomiasis control in Hankou marshland, Wuhan City

To investigate the Oncomelania hupensis snail control effect of schistosomiasis control engineering in marshland within Wuhan City. The engineering measures including surface barrier removal, molluscicide, flatting surface, topsoil stripping, topsoil covering and ditch renovation were applied to transform Hankou marshland. Then the corresponding technical parameters of engineering measures were put forward. The situation of snails was analyzed before and after the transform project. The total length and area of the project were 6 015 m and 87.21 hm2, respectively, including 17.44 hm2 of topsoil landfill, 52.08 hm2 of topsoil covering and 23 new ditches. After the transformation, the average length of the new groove, the groove top width, groove depth, height difference, and the average values of slopes and ditch bottom slope were all increased, while the average values of the width and height of the ditch were decreased. At the same time, the marshland beach surface had a new slope that the embankment was higher than the river and no living O. hupensis snails were found then. The snail breeding environment in Hankou marshland has been effectively changed by the project. However, the constant monitoring and engineering management are still needed to consolidate the effect.

Challenges and countermeasures of forestry schistosomiasis control programs in ecological priority of Yangtze River economic belt development

Relevant projects carried out within the Yangtze River economic belt on the impact of schistosomiasis epidemic and transmission are important issues for "ecological priority" in the process of implementing the strategy. The key problems of schistosomiasis epidemic risk, epidemic happening repeatedly, difficulty of rehabilitating Oncomelania hupensis snail control and schistosomiasis prevention forest, lag of evaluation system and platform construction, lack of basic research, et al. were analyzed in the Yangtze River economic belt taking "ecological priority" as the basis in this paper. Then corresponding countermeasures to these challenges were put forward so as to provide the reference for the national forestry schistosomiasis control programs, which include: execution of the comprehensive prevention and control strategy, scheming of the new round of forestry schistosomiasis control programs, strengthening schistosomiasis prevention and control, promoting productivity in existing forestry to consolidate and improve the achievements of previous forestry schistosomiasis control programs, and promoting the intensity of technological innovation to improve the technological level of forestry schistosomiasis control programs.

Short - term effects of two kinds of plastic mulch on Oncomelania hupensis snail control in irrigation and drainage ditches in Yunnan Province

To evaluate and compare the short-term effects of two kinds of plastic mulch on Oncomelania hupensis snail control in irrigation and drainage ditches with snails in Yunnan Province. The irrigation and drainage ditches with high density of Oncomelania hupensis snails were chosen as the investigation sites, and then 4 groups were set, namely a colorless plastic mulch group, black plastic mulch group, colorless plastic mulch with molluscicide group and black plastic mulch with molluscicide group. The snail situation of the 4 groups was surveyed before the experiment and 7, 14, 21, 30 days after covering plastic mulch, and the snail death rates were compared among the 4 groups. Meanwhile, the hourly temperatures of soil surface, soil surface under plastic mulch and soil layer 5, 15 cm under the surface as well as the weather situation during the study period were measured and recorded. The average snail mortality rate of the colorless plastic mulch group was only 15.29% that was higher than that of the black plastic mulch group (6.56%) (P < 0.01). The average snail mortality rates of the colorless and black plastic mulch with molluscicide groups were 40.80% and 50.15%, respectively, and there was no statistic difference between them (P > 0.05). Both kinds of plastic mulches could raise the temperature of the soil surface under plastic mulch and the soil layer below it, and the temperature of soil under the mulches increased over the cover time, and the average temperature of the soil surface under the black mulch in 30 days was higher than that under the colorless mulch. It is not suitable to use plastic mulch only in irrigation and drainage ditches with snails widely in Yunnan Province because of its low effect, and if necessary, the molluscicide should be added.

Oncomelania hupensis snail control effects of molluscicides with different formulations in field in marshland and lake regions

To observe the Oncomelania hupensis snail control effects of molluscicides with different formulations in the ditch with unstable water level in field of marshland and lake areas, so as to provide the evidence for formulating the prevention strategies. A drainage channel with O. hupensis snails in Jiangling County, Jingzhou City were selected as the study field, then it was divided into 6 segments, except 1 segment was treated as the blank control group for observing the natural mortality rate of the snails, the other 5 segments were treated as observation groups, where 4% niclosamide ethanolamine salt powder, 5% niclosamide ethanolamine salt granule, 25% suspension concentrate of niclosamide ethanolamine salt, 26% suspension concentrate of metaldehyde and niclosamide ethanolamine salt, 50% niclosamide ethanolamine salt wettable powder were applied respectively. Before and after the mollusciciding, the snail surveys were carried out through the systematic sampling method, and the short- and long-term effects of snail control were observed, and the mortality rates of the snails on the slope above the water level and those below the water level were compared. When 7 d and 15 d after mullusciciding, the mortality rates of snails on the slope above the water level in each observation group were 79.52%-97.87% and 90.43%-96.30%, respectively, when compared with those before mollusciciding, all the differences were statistically significant (all P < 0.01). When 7 d after mullusciciding, the mortality rates of snails below the water level in each observation group were 17.11%-50.00%, which were all lower than those of the snails on the slope above the water level in the corresponding groups (all P ＜ 0.05); when 15 d after mullusciciding, the rates were 9.43%-95.24%, and those in 25% suspension concentrate of niclosamide ethanolamine salt, 26% suspension concentrate of metaldehyde and niclosamide ethanolamine salt, 50% niclosamide ethanolamine salt wettable powder groups were all lower than those of the snails on the slope above the water level in the corresponding groups (all P ＜ 0.01). Compared with the densities of living snails before mollusciciding, those 6 months after mollusciciding in each observation group decreased by 70.21%-78.98%. The molluscicides in the formulation of powders and granule are suitable for both the snail environment with or without water, while those in the formulation of suspension agents and wettable powders are suitable only for environments with water.