ABSTRACT
Objective To evaluate the methods in early warning of schistosomiasis and elimination of snails in an ecological public forest in Yexie Town of Songjiang District, and provide the basis for monitoring and controlling snails in forest land in the future. Methods The monitoring data of snails, schistosomiasis and snail elimination in the public forest were collected to evaluate the effect of controlling snails. Results The area with existence of snails was found to be 10.47 hm2, and it was decreased by 98.28% after three times of snail elimination.A total of 1 904 serological tests was performed (test rate of 88.76%) with the positive rate of 0.16%.Pathogenic test result was negative in 3 subjects examined.Serological samples of 11 dogs and 1 sheep were all negative for the test.None of the 1 480 live snails tested was found to be positive in infection.The awareness rate of schistosomiasis control knowledge and behavior formation in 275 students were 98.2% and 95.3%, respectively. Conclusion The snails in the public forest in Yexie Town have been effectively controlled, but there are still scattered living snails.The measures in eliminating and monitoring of snails should be continued and strengthened.
ABSTRACT
Based on the literature research, this paper states the mechanism and measures of the Oncomelania snail control by the schistosomiasis prevention forests, reviews the development process of forestry schistosomiasis control programs, analyzes the new situation and problems, and then puts forward some countermeasures and suggestions about the national forestry program for schistosomiasis control in order to provide new ideas for the goal of schistosomiasis elimination in China in 2025 and the construction of national forestry program for schistosomiasis control.
ABSTRACT
Objective To evaluate the effects of the strategy of transmission interruption of schistosomiasis in Runzhou Dis-trict,Zhenjiang City,Jiangsu Province.Methods The comprehensive prevention and control strategy was carried out in Run-zhouDistrict,Zhenjiang City,Jiangsu Province.The strategy was relied mainly on the Oncomelania hupensis snail control,ex-tended 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 evalua-tion indexes.Results The area with snails controlled was 7 091.50 hm2in 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 schis-tosomiasis in the permanent residents from 2001 to 2016.These serum and fecal positive people of schistosomiasis were all treat-ed 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 Dis-trict,Zhenjiang City in 2016.Conclusion The comprehensive prevention and control strategy including mainly the snail con-trol,extended chemotherapy of schistosomiasis and health education could achieve the goal of transmission interruption of schis-tosomiasis in the areas of marshland along the Yangtze River.
ABSTRACT
Objective 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. Methods The data of schistosomiasis epidemic and its control and preven-tion 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. Results The area with snails in the inside embankment areas of Junshan District decreased by 98.43%,from 1496.66 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 pre-vention and control was 398.857 million RMB in Junshan District,including molluscicide(81.7709 million RMB)and environ-ment reform(213.5 million RMB)respectively. Conclusion 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.
ABSTRACT
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 ana-lyzed in the Yangtze River economic belt taking ecological priority as the basis in this paper. Then corresponding countermea-sures to these challenges were put forward so as to provide the reference for the national forestry schistosomiasis control pro-grams,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 forest-ry to consolidate and improve the achievements of previous forestry schistosomiasis control programs,and promoting the intensi-ty of technological innovation to improve the technological level of forestry schistosomiasis control programs.
ABSTRACT
Objective 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. Methods 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. Results 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 0.05). Both kinds of plastic mulches could raise the temperature of the soil surface under plas-tic mulch and the soil layer below it,and the temperature of soil under the mulches increased over the cover time,and the aver-age temperature of the soil surface under the black mulch in 30 days was higher than that under the colorless mulch. Conclu-sion It is not suitable to use plastic mulch only in irrigation and drainage ditches with snails widely in Yunnan Province be-cause of its low effect,and if necessary,the molluscicide should be added.
ABSTRACT
@#Oncomelania hupensis is the only intermediate host of Schistosoma japonicum. The elimination of Oncomelania snails is the key technique step for schistosomiasis control. This paper summarizes the progress of the techniques of snail control，including the methods of ecology engineering，biology，molluscicides and the study on novel molluscicides，and reviews their features. In addition，this paper explores the appropriate approach to control the snails.
ABSTRACT
Objective To analyze the Oncomelania hupensis snail distribution and the changes of snail situation in Chang-zhou City from 2013 to 2016,so as to provide the evidence for formulating the schistosomiasis prevention and control interven-tions. Methods The data of snail monitoring in Changzhou City from 2013 to 2016 were collected and statistically analyzed. Re-sults 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,3454 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.
ABSTRACT
This article summarized the history, achievements and experiences in controlling and eradicating schistosomiasis in Shanghai under the concerning of Chairman Mao, described the damage of schistosomiasis endemic and decision making as well as the achievement for elimination.The first tide of schistosomiasis elimination (1956-1969) was to mobilize people to involve into detection and treatment of disease.Combined with farmland renovation, snails were controlled in water conservancy facilities.By repeated molluscacide spraying, the snail density reduced remarkably.The second tide of schistosomiasis elimination was carried out during the difficult periods ( 1960-1975 ) . Snail control continued until schistosomiasis eliminated.New methods of detection and snail control were improved.Areas with snails were cleaned one by one until completely eliminated.The third tide of elimination was consolidation and surveillance (1975-1990).After repeated detection and surveillance, in total 30 000 oncomelania were captured in 22 towns, among which none was positive.Detection to 150 000 people was carried out, and no new infectious case was found.No new infectious case was found in middle school students, recruit workers and new students.After 35 years of efforts to the successful elimination of schistosomiasis in Shanghai, both the production of the farmlands and life expectancy increased.
ABSTRACT
Objective: To evaluate the predatory capacity of the Odonata, Hemianax ephippiger nymph as a biocontrol agent for the freshwater snail Lymnaea natalensis, intermediate host of Fasciola gigantica. Methods: Observations on the searching, attacking and devouring of the snails with a series of laboratory-based predation experiments, whose aims were to determine daily predation rate, differential predation on small-, medium- and large-sized snails were carried out. Results: Laboratory evaluation revealed that, the Odonata nymph could kill and consume all three sizes of snails. Searching and handling time of the predator differed depending on snail size and predator vulnerability. The predation rate varied also with respect to snail size and density. Conclusions: Our observations suggested that the predator Hemianax ephippiger may be a suitable bio-control agent of Lymnaea natalensis snail population.
ABSTRACT
Objective To explore a high molluscicidal efficient method in special Oncomelania hupensis snail environments. Methods In 2005 and 2006,in large special environments(rubble creek beaches and seepage barren hills with snails),the me-chanical soil-buried method(excavator digging to bury deep snails)and manual soil-buried method were used respectively,and the results were compared for the cost-effectiveness. Results With the mechanical soil-buried method in 2006,the investment was 0.78 yuan/m2,and the compression rate of snail areas was 100%;with the manual soil-buried method in 2005,the investment was 1.34 yuan/m2,and the compression rate of snail areas was 20.26%. The former was much better than the latter. Conclusion In the large special environments with snails,the mechanical soil-buried method is superior to manual soil-buried method.
ABSTRACT
Objective To evaluate the effects of continuous application of niclosamide ethanolamine salt on Oncomelania hu-pensis snail control in a marshland,river and channel. Methods The Beiwei marshland in Houxiang Town,the Xiaoliang River in Lingkou Town and Laomiao channel in Yunyang Town in Danyang City were selected as study sites,and 4%niclosamide etha-nolamine salt and 26%niclosamide powder were used to kill the snails. Based on the historical records and field investigations, the effects of continuous application of niclosamide ethanolamine salt on snail control were evaluated. Results Compared with the first time of snail repetition,the snail areas decreased by 82.80%,63.14%and 70.00%in the Beiwei marshland,Xiaoliang River and Laomiao channel,respectively,in 2013. There was a positive correlation between the area and density of snails(r=0.931, 0.975 and 0.916,respectively;all P values < 0.05). The average densities of living snails decreased significantly by 92.34%, 87.91%and 97.66%,respectively. There was a negative correlation between the corrected mortality of snails and the average densi-ty of living snails in the following year,and a negative correlation between the reduction rate of living snail density and the average density of living snails in the following year. Conclusion Molluscicides plays an important role in compressing the snail area,re-ducing the snail density,and controlling the schistosomiasis transmission.
ABSTRACT
Objective To analyze the concentration, distribution and decreasing trend of niclosamide in soil through soil heaping mixed with niclosamide and the effect of Oncomelania control, and to explore the appropriate dosage for the 'heaping' method. Methods The soil samples were collected from six groups in Tezi township, Puge county, Sichuan Province, and the dosages were 16, 8, 4, 2, 1 and 0 g/m~2, respectively. After ultrasonic extraction, centrifugence and concentration, the samples were finally determined by high-performance liquid chromatography (HPLC). The mortality rate of snails was observed after 3 days and 7 days. Results The standard error and range of niclosamide in soil were large. There was no significant difference in concentration of niclosamide between the surface layer and deep layer of soil (P>0.05). After 5 months, niclosamide still could be determined in groups of 4 g/m~2. The mortality rate of snails decreased as the concentration of niclosamide decreased (P<0.05). After 5 months, in the group of 4 g/m~2 dosage, the 3 and 7 days mortality rate of snails were 5.33% and 9.33% in the surface layer, higher than the control group (P<0.05). Conclusions The heaping method is an efficacious measure of controlling snails and its recommended dosage is 4 g/m~2.
ABSTRACT
A comprehensive strategy for snail control, including environmental modification and mollusciciding, was implemented in Ya-he River, Changsha County of Hunan Province from 2003 to 2004. The snail status declined significantly in 2005 and 2006, and no snailswere found since 2007. It is indicated that the environmental modification combined with mollusciciding is an effective approach for snailcontrol so as to control the transmission of schistosomiasis.
ABSTRACT
Objective To evaluate the eff ec t of snail control with niclosamide ethanolamine salt dustable powder (DP) in th e marshland of the Yangtze River ahead of the schedule in spring, and to underst and the impact of the low temperature to molluscicidal effect of the dusting. Methods The snail control test with niclosamide ethanolamine salt dustable powder was carried out under different te mperatures in laboratory. Then the snail control was undertaken in the marshland of the Yangtze River ahead of the schedule in spring, and the molluscicidal ef fect was observed and the temperature changes were also considered. Results When the temperature was 15 ℃ and 25 ℃ respectively, there was no significant difference on the molluscicidal effec t of niclosamide ethanolamine salt DP in laboratory. The average atmosphere temp erature in each day was 8.9-16.3 ℃ from the last ten-day of March to the fir st ten-day of April in Nanjing regions. The corrected mortality of snails and the r educed rates of density of snails were 95.38% and 99.97% respectively on the s ur face of the soil in the marshland field. The corrected mortality and the reduced rates of density of snails were 79.30% and 70.59% respectively in the surface l ayer of the soil. Conclusion The impact of air t emperature is little to the molluscicidal effect of niclosamide ethanolamine sal t DP when the average atmosphere temperature in each day was 10-15 ℃ in the ma r shland of the Yangtze River. If the snail control is undertaken ahead of the sch edule in spring, the reproduction of snails will be suppressed and the infection of Schistosma japonicum will be controlled. [
ABSTRACT
Objective To validate the molluscicidal effect of magnesium borate ore powder (MBOP), and explore the mechanism for providing the scientific basis for the field use. Methods The experiments were performed by the Copper Coin method, Volatilization method and Immersion and Sprinkle methods recommended by WHO. Results The MBOP can't kill the snail by the volatilization. The molluscicidal effect was well by the Immersion and Sprinkle methods. The acted effect was quick by using the Immersion method while the effect was more stable by using the Sprinkle method.LD_(50) of the Sprinkle method (27℃,4 days) was 4.07 g/m2. Conclusion MBOP's molluscicidal effectiveness is well, the action appears gradually and the effect is stable. The possible mechanism of MBOP might act through some dissolved components.
ABSTRACT
Objective To evaluate the effectiveness of the current measure of Oncomelania hupensis control in Jiangsu Province. Methods The snail control was carried out with molluscicides in the high transmission areas every year. Some snail habitat areas were modified. The snail areas within three years were re-treated with molluscicides in the maintenance phase. The snail survey was carried out every spring, and the data were analysed with SAS software. Results From 1995 to 2001, 14519.17 hm 2 of snail habitats were molluscicided, 2768.57 hm 2 were modified, and 8803.64 hm 2 were re-treated with molluscicides in the maintenance phase. The coverage rates of snail control areas dropped by 19.14% every year. The snail areas increased by 6.25% every year from 1995 to 2002. In which, the areas of infected snails increased by 18.52% every year. The correlation analysis showed that the areas of infected snails increased with the increasing of the total snail areas. At the same time, the areas of infected snails increased with the fall of the coverage rates of snail control areas. The analysis of the snail distribution showed that the main problem was poor snail control. Conclusion In recent years, the rise of area of snail habitats is serious in Jiangsu Province. The present measures of the snail control have not effectively stopped the spreading and increasing of snails. The research on the new molluscicides, the new methods of snail control and the better policies are very important.