Effect and cost-effectiveness of three commonly used molluscicides in largescale field application / 中国血吸虫病防治杂志

Objective To evaluate the effect and cost-effectiveness of three commonly used molluscicides, 4% "Luo-wei" (tea-seed distilled saponins, TDS), 50% niclosamide ethanolamine salt wettable powder (NESWP), and 26% metaldehyde and niclosamide suspension concentrate (MNSC) in large-scale field application, so as to provide the references for formulating the strategy of snail control. Methods The field test and parallel comparison were implemented. A marshland with Oncomelania hupensis snails of the Yangtze River was divided into 4 parts (10 hm2) for the research, and three of them were experimental areas while the last one was a blank control area. The experimental areas were sprayed with 4% "Luo-wei", 50% NESWP and 26% MNSC respectively for 3 times and the interval was 1 week. Seven days after each spraying the effect of snail control was investigated, and the costs of molluscicides, labor, transportation, fuel consumption and mechanical loss were recorded. The cost of each molluscicide, snail mortality, snail density, and the cost of increasing 1% of snail mortality per 100 m2 were analyzed and compared. Results After the first, second and third spraying, the corrected snail mortality rates were 67.34%, 76.55% and 84.60% respectively in the 4% "Luo-wei" group; the corrected snail mortality rates were 64.71%, 75.17% and 83.89% respectively in the 50% NESWP group; the corrected snail mortality rates were 66.55%, 76.27% and 86.67% respectively in the 26% MNSC group. There was no significant difference among the 3 groups in the snail mortality at the same spraying time (χ2 = 1.590, 0.571, 3.238, all P > 0.05) . In addition, along with the increase of the spraying times, the snail mortality of each group was increased significantly compared to that of the control group (χ2 = 79.333, 94.718, 117.020, all P < 0.01) . After the first, second and third spraying, the reduction rates of snail density were 69.82%–86.60% in the 4% "Luo-wei" group, 68.66%–86.55% in the 50% NESWP group, and 71.89%–88.87% in the 26% MNSC group respectively. The decreasing amplitude of the snail density was more than 85% in all the experimental areas after 3 rounds of spraying molluscicide. The snail control costs per 100 hm2 were 19.57, 11.97 Yuan and 10.47 Yuan in the 4% "Luo-wei" group, 50% NESWP group, and 26% MNSC group respectively. After the first, second and third spraying, the costs of increasing 1% of snail mortality per 100 m2 were 0.30, 2.08 Yuan and 2.38 Yuan in the 4% "Luo-wei" group, 0.20, 1.10 Yuan and 1.32 Yuan in the 50% NESWP group, and 0.17, 1.04 Yuan and 0.97 Yuan in the 26% MNSC group respectively, and the cost-effectiveness was the highest at the first spraying in all the three groups. Conclusions The effects of the three molluscicides for snail control are similar, but the efficacy of snail control is reduced as the spraying time increases.

[Effect and cost-effectiveness of three commonly used molluscicides in largescale field application].

OBJECTIVE: To evaluate the effect and cost-effectiveness of three commonly used molluscicides, 4% "Luo-wei" (tea-seed distilled saponins, TDS), 50% niclosamide ethanolamine salt wettable powder (NESWP), and 26% metaldehyde and niclosamide suspension concentrate (MNSC) in large-scale field application, so as to provide the references for formulating the strategy of snail control. METHODS: The field test and parallel comparison were implemented. A marshland with Oncomelania hupensis snails of the Yangtze River was divided into 4 parts (10 hm2) for the research, and three of them were experimental areas while the last one was a blank control area. The experimental areas were sprayed with 4% "Luo-wei", 50% NESWP and 26% MNSC respectively for 3 times and the interval was 1 week. Seven days after each spraying the effect of snail control was investigated, and the costs of molluscicides, labor, transportation, fuel consumption and mechanical loss were recorded. The cost of each molluscicide, snail mortality, snail density, and the cost of increasing 1% of snail mortality per 100 m2 were analyzed and compared. RESULTS: After the first, second and third spraying, the corrected snail mortality rates were 67.34%, 76.55% and 84.60% respectively in the 4% "Luo-wei" group; the corrected snail mortality rates were 64.71%, 75.17% and 83.89% respectively in the 50% NESWP group; the corrected snail mortality rates were 66.55%, 76.27% and 86.67% respectively in the 26% MNSC group. There was no significant difference among the 3 groups in the snail mortality at the same spraying time (χ2 = 1.590, 0.571, 3.238, all P > 0.05) . In addition, along with the increase of the spraying times, the snail mortality of each group was increased significantly compared to that of the control group (χ2 = 79.333, 94.718, 117.020, all P < 0.01) . After the first, second and third spraying, the reduction rates of snail density were 69.82%-86.60% in the 4% "Luo-wei" group, 68.66%-86.55% in the 50% NESWP group, and 71.89%-88.87% in the 26% MNSC group respectively. The decreasing amplitude of the snail density was more than 85% in all the experimental areas after 3 rounds of spraying molluscicide. The snail control costs per 100 hm2 were 19.57, 11.97 Yuan and 10.47 Yuan in the 4% "Luo-wei" group, 50% NESWP group, and 26% MNSC group respectively. After the first, second and third spraying, the costs of increasing 1% of snail mortality per 100 m2 were 0.30, 2.08 Yuan and 2.38 Yuan in the 4% "Luo-wei" group, 0.20, 1.10 Yuan and 1.32 Yuan in the 50% NESWP group, and 0.17, 1.04 Yuan and 0.97 Yuan in the 26% MNSC group respectively, and the cost-effectiveness was the highest at the first spraying in all the three groups. CONCLUSIONS: The effects of the three molluscicides for snail control are similar, but the efficacy of snail control is reduced as the spraying time increases.

Effect and cost-effectiveness of three commonly used molluscicides in largescale field application / 中国血吸虫病防治杂志

Objective To evaluate the effect and cost-effectiveness of three commonly used molluscicides, 4% "Luo-wei" (tea-seed distilled saponins, TDS), 50% niclosamide ethanolamine salt wettable powder (NESWP), and 26% metaldehyde and niclosamide suspension concentrate (MNSC) in large-scale field application, so as to provide the references for formulating the strategy of snail control. Methods The field test and parallel comparison were implemented. A marshland with Oncomelania hupensis snails of the Yangtze River was divided into 4 parts (10 hm2) for the research, and three of them were experimental areas while the last one was a blank control area. The experimental areas were sprayed with 4% "Luo-wei", 50% NESWP and 26% MNSC respectively for 3 times and the interval was 1 week. Seven days after each spraying the effect of snail control was investigated, and the costs of molluscicides, labor, transportation, fuel consumption and mechanical loss were recorded. The cost of each molluscicide, snail mortality, snail density, and the cost of increasing 1% of snail mortality per 100 m2 were analyzed and compared. Results After the first, second and third spraying, the corrected snail mortality rates were 67.34%, 76.55% and 84.60% respectively in the 4% "Luo-wei" group; the corrected snail mortality rates were 64.71%, 75.17% and 83.89% respectively in the 50% NESWP group; the corrected snail mortality rates were 66.55%, 76.27% and 86.67% respectively in the 26% MNSC group. There was no significant difference among the 3 groups in the snail mortality at the same spraying time (χ2 = 1.590, 0.571, 3.238, all P > 0.05) . In addition, along with the increase of the spraying times, the snail mortality of each group was increased significantly compared to that of the control group (χ2 = 79.333, 94.718, 117.020, all P < 0.01) . After the first, second and third spraying, the reduction rates of snail density were 69.82%–86.60% in the 4% "Luo-wei" group, 68.66%–86.55% in the 50% NESWP group, and 71.89%–88.87% in the 26% MNSC group respectively. The decreasing amplitude of the snail density was more than 85% in all the experimental areas after 3 rounds of spraying molluscicide. The snail control costs per 100 hm2 were 19.57, 11.97 Yuan and 10.47 Yuan in the 4% "Luo-wei" group, 50% NESWP group, and 26% MNSC group respectively. After the first, second and third spraying, the costs of increasing 1% of snail mortality per 100 m2 were 0.30, 2.08 Yuan and 2.38 Yuan in the 4% "Luo-wei" group, 0.20, 1.10 Yuan and 1.32 Yuan in the 50% NESWP group, and 0.17, 1.04 Yuan and 0.97 Yuan in the 26% MNSC group respectively, and the cost-effectiveness was the highest at the first spraying in all the three groups. Conclusions The effects of the three molluscicides for snail control are similar, but the efficacy of snail control is reduced as the spraying time increases.

[Epidemiological characteristics of malaria in Yizheng City from 2000 to 2016].

OBJECTIVE: To explore the epidemiological characteristics of malaria in Yizheng City, so as to provide a reference for formulating the control strategy in the future. METHODS: The data of malaria case reports and prevention and control work in Yizheng City were collected and retrospectively analyzed. RESULTS: Totally 55 malaria cases were found in Yizheng City from 2000 to 2016 with an average incidence of 0.56/105. The malaria cases were local cases from 2000 to 2010 and since 2011 they were all imported cases. CONCLUSIONS: The endemic situation of malarial in Yizheng City is stable and no local infection cases occur in this place for six consecutive years. The imported cases should be paid more attention to in the future control work.

[Surveillance and risk assessment system of schistosomiasis in Jiangsu Province â ¢ Risk of schistosomiasis transmission in the area along the Yangtze River in Yangzhou City].

OBJECTIVE: To evaluate the potential risk of schistosomiasis transmission in the area along the Yangtze River in Yangzhou City, so as to provide evidences for establishing a post-transmission surveillance system for schistosomiasis in marshland regions. METHODS: The water infectivity, floating boatmen and fishermen infection, reservoir host infection and wild feces contamination were investigated in five districts/counties along the Yangtze River in Yangzhou City, including Guangling, Hanjiang, Jiangdu, Yizheng and Development Zone, and the transmission factors and risky characteristics were assessed after interruption of schistosomiasis transmission in marshland regions. RESULTS: A total of 15 key water regions were identified in the area along the Yangtze River in Yangzhou City in 2015. A total of 1 500 sentinel mice were placed, after breeding, their overall survival rate was 99.33%; 1 490 were dissected, with no schistosome infection. Of the 5 576 floating boatmen and fishermen examined, no schistosome infection was observed, and among the 3 566 domestic animals (including 171 cattle, 1 895 sheep and 1 500 pigs), no infections were detected. During the period between January and March, 2016, there were 3 200 mouse traps placed on 8 marshlands, and 62 wild mice were captured from 6 marshlands, with a capture rate of 1.94%, and no schistosomeinfected wild mice were seen. In addition, there were 35 pieces of fresh wild feces captured from 7 marshlands, including 11 pieces of bovine feces (31.43%), 17 pieces of sheep feces (48.57%), 2 pieces of dog feces (5.71%) and 5 pieces of other feces (14.29%), and no infections were detected. CONCLUSIONS: There is a low risk of schistosomiasis transmission in the area along the Yangtze River in Yangzhou City. However, the contamination of feces from bovine and sheep that are freely pastured on marshlands is a big threat to schistosomiasis control.

[Study on schistosomiasis control measures in mobile boat fishermen. III. Construction and application of regional joint mechanism for schistosomiasis examination and treatment in boatmen].

OBJECTIVE: To construct the regional joint mechanism for schistosomiasis examination and treatment and the examination protocol among mobile boatmen, so as to provide effective measures for control of mobile infectious sources of schistosomiasis in the Yangtze River basin. METHODS: According to the characteristics of the cargo frequent mobility of ships with fixed anchor points, the health, maritime and transport sections were jointly cooperated to set up sites for schistosomiasis examination and treatment in ship locks, wharfs and harbors. The infection of schistosomiasis was detected by means of rapid immunological screening and stool examination, and the regional joint mechanism was constructed. The sero-positives were traced for further parasitological examinations and treatment by using the regional joint network for schistosomiasis examination and treatment. The schistosome infections in boatmen were analyzed and compared between different examination and treatment sites and among different navigation coverage. RESULTS: A total of 16 sites for examination and treatment of schistosomiasis, including 5 fixed sites and 11 mobile sites, were set up in 12 townships of 6 districts (counties) of Yangzhou City. During a period between June and August, the examination of schistosomiasis was conducted in 40 sites, and of the 1 225 boatmen from 967 boats detected, 19 cases were sero-positive, with a positive rate of 1.55%. Among the 14 sero-positives examined, no stool positive patients were found. Among the 1 225 boatmen detected, 820 were from fixed sites and 405 from mobile sites, and 4 and 15 cases were found, respectively, with positive rates of 0.49% and 3.70%, respectively, and the sero-positive rate was higher in mobile sites and that in fixed sites. A total of 898 boatmen from the Yangtze River basin and 305 from the local inland rivers were examined, and 3 and 16 sero-positive cases were detected, respectively, with positive rates of 0.33% and 5.25%, respectively, and the sero-positive rate was significantly higher in the boatmen from the local inland rivers than that from the Yangtze River basin. CONCLUSION: Regional joint mechanism is an effective strategy for examination and treatment of schistosomiasis among mobile boatmen, which provides a new approach to control mobile infectious sources of schistosomiasis in the Yangtze River basin.