[Study on distribution and countermeasures of Oncomelania snails in beach wetlands of Runzhou section of lower reaches of Yangtze River].

OBJECTIVE: To understand the distribution of the river beach wetlands and Oncomelania snails in the lower reaches of the Yangtze River, and explore the countermeasures of snail control. METHODS: The river beach wetlands outside the Yangtze River levee were investigated and classified according to the hierarchical and classification system of wetlands of China. The snail survey was carried out in the beach wetlands of Runzhou section of lower reaches of the Yangtze River from 2004 to 2013. The change trend of snail areas and the densities was analyzed in the wetlands. RESULTS: The river beach of Runzhou section of lower reaches of the Yangtze River belongs to the riverine wetland. There was Oncomelania snail breeding except the permanent water area. At present, there were natural wetlands of 1303.0 hm2, human-made wetlands of 1479.0 hmb2 and wetland function changes of 1059.0 hm2 in the river beach of Runzhou section. There was the snail area of 181.4 hm2 in the natural wetland in 2013. The area of snail control by the molluscicide and environmental modification was 4624.55 hm2 from 2004 to 2013. The decline rates of snail areas and densities were 66.53% and 77.66% respectively. The existing Oncomelania snails were distributed in the natural wetlands. CONCLUSION: The human-made wetland is helpful to snail control. The snail control in the river beach wetlands should attach a great importance to the protection of wetland ecology.

[Effect of comprehensive prevention and control of soil-transmitted nematodiasis in Runzhou District of Zhenjiang City].

OBJECTIVE: To evaluate the effect of comprehensive prevention and control of soil-transmitted nematodiasis in Runzhou District, Zhenjiang City, Jiangsu Province from 1997 to 2012. METHODS: The comprehensive prevention and control measures included the helminthicide, health education, improvement of water supplier and harmless toilets, and these measures were implemented continuously. At the same time, the infection rates of soil-transmitted nematodes, the local economic indicators, and the coverage rates of tap water and harmless toilets were surveyed. RESULTS: The mass chemotherapy was performed for 202 100 person-times and the diagnosed chemotherapy was performed for 2 006 person-times in Runzhou District from 1997 to 2012. The awareness rates of health knowledge were 57.18% in 1997, and 95.62% in 2012. The coverage rates of tap water and harmless toilets were 10.14% and 10.21% in 1997, and 100.0% and 90.38% in 2012, respectively. There were negative correlations between the awareness rate of per capita GDP, per capita net income, coverage rates of tap water, coverage rates of harmless toilets, health knowledge and the infection rate of soil-transmitted nematodes, respectively (r(per capitaGDP) = -0.526, P < 0.05; r(per capita net income) = -0.671, P < 0.01; r(coverage rates of tap water) = -0.936, P < 0.01; r(coverage rates of harmless toilets) = -0.922, P < 0.01; r(awareness) = -0.774, P < 0.01). The statistical analysis showed that the infection rate of soil-transmitted nematodes had a downward trend as an exponential curve in Runzhou District from 1997 to 2012 (y = 42.031 7e(-0.357 6x), R2 = 0.803 6, F = 57.28, P = 0.000). The infection rate of degradation by an annual rate was 29.18%. The infection rate in farmers was significantly higher than that in students (χ2 = 17.998, P < 0.01). There was no significant difference between men and women in the infection rate of soil-transmitted nematodes (χ2 = 3.627, P = 0.057). CONCLUSION: The comprehensive prevention and control measures and the development of social economy contribute to the steady decline of soil-transmitted nematode infections.

[Effect of comprehensive schistosomiasis prevention and control strategy in Runzhou District, Zhenjiang City].

The comprehensive schistosomiasis prevention and control strategy which relied mainly on Oncomelania snail control, schistosomiasis detection and chemotherapy in residents and livestock was carried out in Runzhou District, 2004-2011. There were no acute schistosomiasis patients for 7 years and no acute schistosomiasis occurred in livestock for 8 years. A total of 107 331 person-times were examined by the serological test and the number of positive cases was 843 (0.8%), and there were 796 person-times who received chemotherapy from 2004 to 2011. There were no infected snails for 2 successive years. Runzhou District achieved the criteria of schistosomiasis endemic control in 2007 and the criteria of schistosomiasis transmission interrupted in 2011. The comprehensive schistosomiasis prevention and control strategy is very effective in Runzhou District.

[Effect and cost-benefit of Oncomelania snail control by plowing and planting in Jiaobei Beach of Zhenjiang City].

OBJECTIVE: To evaluate the effect and cost-benefit of Oncomelania snail control by plowing and planting in Jiaobei Beach of Zhenjiang City. METHODS: In 2009, the measures of building low dike and plowing and planting were implemented in the experimental area of the east part of Jiaobei Beach, while in the control area of the west part of the beach, the molluscacide (niclosamide) was used to control snails. Then, the snail control effects and the cost-benefits of the two groups were compared. RESULTS: In the experimental area, the density of living snails decreased by 99.75% in the year when the measures were implemented, and no living snails were found from the second year. Though that the density of living snails in the control area decreased by 70% around, it aroused again in the second year. The net cost-benefit ratios of the experimental area and the control area were 2.18 and -0.92, respectively. CONCLUSION: Building low dike and plowing and planting in the beaches along the middle and lower reaches of the Yangtze River can effectively control snails, meanwhile, it is economic.