[Oncomelania hupensis snail situation in wetlands surrounding reservoirs in hilly areas in Danling County].

OBJECTIVE: To master the Oncomelania hupensis snail situation in wetlands surrounding reservoirs in hilly areas in Danling County, Sichuan Province, so as to provide the reference for improving the snail control in these areas. METHODS: A medium-sized reservoir (Meiwan Reservoir) and a small-sized reservoir (Zhulinkan Reservoir) were chosen respectively , and the snail situation of the environments surrounding the reservoirs were investigated , the indexes such as the occurrence rate of frames with snails and the density of living snails at the upstream and downstream of the reservoirs as well as the surrounding environments were calculated and compared. Meanwhile , the data of the snail situation of the adjacent villages in the irrigation district at the downstream of the reservoirs year by year were collected to analyze the variation trend. RESULTS: The Meiwan Reservoir was located in the deep hill, the occurrence rate of frames with snails was 4.29%, the highest and average densities of living snails were 28.00 snails/0.1 m2 and 0.38 snails/0.1 m2, respectively. There was a statistically significant difference between the occurrence rates of frames with snails at the upstream and downstream, which were 0.17% and 22.16%, respectively (χ2 = 1,267.40, P < 0.05), and the rate of spillway was the highest (51.69%). The highest and average densities of living snails in the downstream were 7.00 and 656.10 times higher than those in the upstream respectively. The Zhulinkan Reservoir was located in the shallow hill, the occurrence rate of frames with snails was 17.29%, and the highest and average densities of the living snails were 38.00 snails/0.1 m2 and 0.61 snails/0.1 in 2, respectively. There was a statistically significant difference between the occurrence rates of frames with snails at the upstream and the downstream, which were 12.95% and 50.92% respectively (χ2 = 194.68, P < 0.05), and the rate of spillway was the highest (65.74%). The highest and average densities of living snails in the downstream were 5.43 and 10.00 times higher than those in the upstream respectively. After the construction of the two reservoirs, the snail area in the irrigation districts of the adjacent villages at the downstream was 57.26% of that before and after the construction (398,030 m2/695 160 m2). The snail area showed a down-ward tendency with repeatedly rebound since the 1990s. CONCLUSIONS: The wetland surrounding the reservoir in hilly region is suitable for snail breeding, and the snail situation in the shallow hill is more serious than that in the deep hill. There exists a risk for the repeatability of snail situation in this type of area where the snails can easily diffuse.

[Surveillance of schistosome antibodies in population in mountainous schistosomiasis endemic regions in China].

OBJECTIVE: To understand the dynamics of schistosome antibodies in population in mountainous schistosomiasis low endemic regions, China, so as to provide the evaluation reference for immunodiagnosis. METHODS: The people who consecutively received the indirect heamagglutination assay (IHA) for schistosomiasis and Kato-Katz technique were enrolled in this study in Guixiang Village, Danling County, Sichuan Province from 2006 to 2011. The positive rates for schistosome antibodies, antibody titers and eggs per gram (EPG) were analyzed. RESULTS: A total of 353 people were investigated in this study from 2006 to 2011. The positive rates for schistosome antibodies decreased from 20.73% to 13.67%, and the geometric mean reciprocal titer (GMRT) decreased from 1.63 to 1.06. The antibodies tended to be negative in most antibody-positive people and the GMRT decreased gradually. The antibodies remained negative in most antibody-negative people. After chemotherapy in parasitology confirmed patients, the positive rate for schistosome antibodies decreased from 100% to 20%, and the GMRT decreased from 34.29 to 1.58. There was a highly positive correlation between GMRT and EPG (r = 0.94, P < 0.05). CONCLUSION: The positive rate for schistosome antibodies in population in mountainous schistosomiasis low endemic regions is relatively high (13.67%). The standardization of immunodiagnostic methods is necessary and the suitable diagnostic reagents should be developed in this region.

[Effect of comprehensive control pattern on soil-transmitted nematodiasis in Danling County].

The comprehensive control pattern centering on health education, deworming and improving drinking water and lavatories was adopted to control soil-transmitted nematodiasis in Danling County, Sichuan Province from 2007-2009. In 2009, the infection rate of soil-transmitted nematodes decreased from 57.12% of the baseline survey in 2006 to 10.06%.