ABSTRACT
Objective To observe the Oncomelania hupensis snail control effects of molluscicides with different formula?tions 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. Methods 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 ethanol?amine 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. Results 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 ethanol?amine 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%. Conclusions 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.
ABSTRACT
Objective To develop a Jingcen DY?1 type spraying tanker for Oncomelania hupensis snail control and evaluate its effect of field application as well as the cost. Methods The currently available tractor was used as a vector,and the mechan?ical and electrical equipments and containers were integrated with shafts,pipelines and electric lines to produce a spraying tank?er for snail control,with the functions of carrying people and molluscicides,generating electric power and getting water,mixing stocking solutions,adjusting molluscicide solutions evenly,and spraying drugs. The volume of the molluscicide solution,flow rate of water injection,and the flow rate,range and advance speed of the spray gun were tested,and the solution concentrations of molluscicide in the tanker and at the muzzle of the spray gun at different time were detected. Meanwhile,the molluscicidal ef?fect and cost of the spraying tanker were analyzed by the field test. Results The volume of the liquid storage pot of the Jingcen DY?1 type spraying tanker was 1 800 L,the flow rate of water injection was 400 L/min,the flow rate and the spray range of the standard spray gun were 110-200 L/min and 19.70-23.50 m,respectively,the efficiency of drug spraying of the spraying tanker was 6 000 m2/h,and the ratio of spray width(m)to march speed(m/min)was 1∶200. When 5 min post mother liquid recirculat?ing ,the average concentration of the molluscicide at the upper? ,middle? and lower?layers of the liquid storage pot was (1 030.39 ± 43.00)mg/L,with a variation coefficient of 4.17%. The average concentration of the molluscicide in the spraying process(spraying for 2,4,6,8,9 min)was(953.00 ± 68.87)mg/L,with a variation coefficient of 7.22%. The concentration of the residual drug in the liquid storage pot post spraying was 1 000.43 mg/L,which reached the effect concentration for snail con?trol. After spraying for 7 days in the field,the average density of living snails reduced by 88.20% as compared to that before spraying,and the adjusted mortality of snails was 87.65%. The unit cost of Jingcen DY?1 spraying tanker was 0.086 7 Yuan/m2, which reduced by 58.20% as compared to that of the conventional spraying tanker. Conclusions Jingcen DY?1 type spraying tanker for snail control which integrates various equipments together can effectively control the concentration and dose of the mol?luscicide,and the machine is labor?saving,efficient,economic and well adapted,and is worthy to be widely applied.
ABSTRACT
Objective To classify and grade the environments with Oncomelania hupensis snails inside embankment in marsh-land and lake areas,so as to improve the work efficiency and realize the systematic management. Methods The schistosomiasis endemic area Liaodi and Xiongdi villages in Jiangling County,Hubei Province were selected as the experiment villages,and the environments with snails in the two villages were divided into sections with a length of 500m,then the snail situation were sur-veyed by the systematic sampling method with 10m and 50m a frame respectively. The environments were classified according to the discovery of infected snails and wild fecal contamination,and the numbers of sites with snails and their areas in different class-es were recorded. Meanwhile,the data of sites with infected snails in Jingzhou City during the recent 5 years were collected and graded according to the average density of snails,so as to discuss the correlativity between the grades of environments with snails and the numbers of sites with infected snails and the occurrence rate of frames with snails. Results There were 1 967 sites with in-fected snails in Jingzhou City during the recent 5 years,and there was a positive correlation between the grades of environments with snails and the occurrence rate of frames with snails(rs=0.77,P0.05),but the time-consuming of the former was 3 times of the latter. Conclusions The classification and grading of the environments with snails inside embankment in marshland and lake areas can master the key point of the snail survey. The subsection and setting frames at a suitable distance can save time and manpower,improve work efficiency,as well as understand the distribution of snail status of the environment with snails,which can realize the sort management of the snail envi-ronments inside embankment.
ABSTRACT
Objective To understand the key risk factors of schistosomiasis transmission in Jingzhou City,so as to provide the evidence for improving the treatment of these risk factors. Methods Each village of six counties was investigated and 3 envi-ronments were surveyed each village for the distribution of Oncomelania snails and animal stools in the field. The results were ana-lyzed and the risk factors of schistosomiasis transmission were assessed. Results The density of living snails was 0.43 snails per 0.1 m2,the frequency of the frames with snails was 9.12%,and no schistosome infected snails were found. All of the animal stools collected from the field were from bovines. The schistosome positive rate of animal stools was 37.50%(3/8)among the environ-ments,and the schistosome infection rate of stools was 8.11%(3/37). The schistosome infection rate of animal stools was 0 near the residence living sites,and the positive rates were 12.50%and 8.33%in the ditches and slopes,respectively(χ2=0.07,P>0.05). Conclusions Bovine is still the main infectious source of schistosomiasis,i.e. the main risk factor of the disease transmis-sion. Therefore,the strategy of controlling bovine should be strengthened.
ABSTRACT
Objective To evaluate the detection rate and the efficiency of the modified crushing-cercariae escaping method.Methods The detection rates of the modified crushing-cercariae escaping method and the crushing methods were compared by using a double-blind control experiment with the latter as a gold standard.meanwhile the number of the cercariae was quantified.The efficiency of the two methods aforementioned and the cereariae escaping method were compared in field.Results The detection rate of the modified crushing-cercariae escaping method was 100%.the average number of cercariae in each infected snail was (4 778±1 157);and the number in certain volume of water sample was positively correlated with the number of infected snails.The efficiency of the modified menthed Was 18.2 times and 17.3 times as high as those of the crushing method and cereariae escaping method,respectively.Conclusions The modified crushing-cercariae escaping method Can detect the infected snails quicky and Can quantify the number of infected snails and cercariae,and is suitable for the detection of infected snails in large number.
ABSTRACT
According to the National Scheme of Shistosomiasis Surveillance,the endemic situation in 8 national surveillance sites in Jingzhou City were monitored and analyzed.The results showed that the average human infection rate in 8 sites was 0.93%,and the rates in residents above 40 years old were high.People with positive results in fecal examination were all farmers,with an infection rate of 1.16%.The average infection rate of cattle was 6.26%.The total snail area was 1 511.50 hm~2,among which an area of 0.98 hm~2 was newly discovered and the area with infected snails was 1.17 hm~2.It concludes that the endemie situation in surveillance sites decreases year by year.However,the infection rate of earle still remains high and the snail status is still severe,which suggests that the control should be strengthened further.