[Relationship between snails and recent water level in different marshlands in Xingzi County, Jiangxi Province].

OBJECTIVE: To study the longitudinal change of data on Oncomelania hupensis surveillance in different marshlands and the impact of recent water level in Xingzi County, Jiangxi Province. METHODS: All information including water level of hydrometric station and the data of snails at the marshlands of Xiguanhu, Majiawan and Ximiaoqian was collected to explore the longitudinal change of snails and analyze the relationship between snail distribution and recent water level with Spearman rank correlation analysis. RESULTS: The highest proportion of frames with living snails and living snail densities at Majiawan and Ximiaoqian was 89.66% (442/493) in 2002 and 66.72% (872/1 307) in 2007, 8.33 in 2001 and 7.39 snails per frame in 2006, respectively, and the lowest was 13.26% (126/950) in 2010 and 4.60% (55/1 195) in 2005, 0.42 in 2010 and 0.22 snails per frame in 2002, respectively, and tended to decrease gradually after 2007. At Majiawan, infected snails were found in 2005 and 2009, the density and proportion of infected snails were 0.0033 and 0.0025 snails per frame, 0.09% (3/3 306) and 0.22% (3/1 389). Infected snails were found in Ximiaoqian in 2001, 2003, 2005 and 2009, the highest density and proportion of infected snails were 0.005 0 snails per frame and 0.88% (6/684) in 2005. Infected snails were found in Xiguanhu in 2002 and 2003 with a density and proportion of 0.0029 and 0.0027 snails per frame, 0.10% (1/974) and 0.32% (1/312), respectively. The correlation analysis between proportion of frames with living snails and density at Xiguanhu with the average water level of the first and second month before snail survey showed statistical significance, the correlation coefficient was 0.76, 0.71, 0.82 and 0.78 (P<0.05), respectively. The correlation between proportion of frames with living snails and density at Majiawan showed no statistical significance with the average water level of recent three months before snail survey. The proportion of frames with living snails and density at Xiguanhu were negatively correlated with the average water level of the first and second month before snail survey, the correlation coefficient was -0.67, -0.75, -0.79 and -0.72 (P<0.05), respectively. CONCLUSION: The change trend of snail indicators in different marshlands in the County and impact of water level in recent three months on snail population are both different, and the snail control strategy in marshlands should therefore be adjusted.

[Preliminary study on applying high resolution CBERS images to identify Oncomelania snail habitats in lake and marshland regions].

OBJECTIVE: To explore the preliminary application of high resolution CBERS-02B images in detecting the Oncomelania snail habitats in lake and marshland regions. METHODS: The images with high resolutions were first fused from CBERS-02B HR and CCD images, and then the potential snail habitats in Xingzi County of Jiangxi Province were extracted from high resolution CBERS images and CCD images, respectively. A total of 2 000 validation points were randomly selected for comparing the difference of distribution of these points inside and outside of the extracted two snail habitats with the McNemar chi-square test. RESULTS: The areas of the two snail habitats extracted from high resolution and CCD images were 98.23 km2 and 94.89 km2, respectively. The numbers of validation points in the two snail habitats were 255 and 248, respectively, and no significant difference was found (chi2 =177 9.52, P = 0.23). CONCLUSION: At large-scale studies, the ranges and areas of the two snail habitats extracted from high resolution and CCD images are not significantly different.

[Surveillance of schistosomiasis in Zhuxi Village, Xingzi County, 2005-2010].

OBJECTIVE: To understand the effect of schistosomiasis control in Zhuxi Village, Xingzi County, Jiangxi Province. METHODS: According to the national scheme of schistosomiasis surveillance, we investigated the schistosomiasis epidemic in Zhuxi Village from 2005-2010. The epidemic data of schistosomiasis on the humans, farm cattle, and Oncomelania snails were collected, respectively and analyzed by using the method of Cochran-Armitage test. RESULTS: Human infections and snail infections showed dynamic fluctuations (Z = 3.35, P = 0.000 8) and the density of alive snails tended to decrease gradually. The majority of the infections were peasants and students. The infection rates of farm cattle were 12.31%, 3.23%, 2.94%, 3.33%, 4.44% and 2.15%, respectively from 2005-2010. CONCLUSION: The effect of schistosomiasis control is very fine and schistosomiasis has been well controlled.