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Objective To evaluate the effect of an integrated control strategy and to quantify the spatial-temporal variation of infected snails in the bottomland areas after the strategy was implemented.Methods Based on the geographic database of infected snail distribution at the village level during 2004-2010 in Anxiang county,Hunan province,spatial autocorrelation analysis and spatial scan statistics were applied to analyze the spatial-temporal characteristics on the distribution of infected snails.Results The number of embankments with infected snails in Anxiang county decreased from 23 in 2004 to 10 in 2010,while the rate of frame with infected snail in embankments decreased from 4.32‰ in 2004 to 0.12‰ in 2010.The spatial distribution of infected snails was nonrandom,only in 2004 and 2005 with Moran's I=0.21 (P＜0.10) and Moran's I=0.13 (P＜0.10) respectively.Data from the local spatial auto-correlation analysis showed that the number of villages with H-H types of auto-correlation model had been gradually decreasing.The results of SaTScan statistics appeared the same as from the local spatial auto-correlation analysis,showing that the number of areas with increased risk was decreasing.Conclusion The comprehensive measures with emphasis on infectious source control seemed effective for schistosomiasis control program.The current distribution characteristics provided us with evidence that the resource assignment could be more reasonably implemented so as to control schistosomiasis in a more effective way.
RESUMO
OBJECTIVE: To evaluate the effect of a comprehensive schistosomiasis control strategy based on buffalo removal in a lake and marshland region. METHODS: A community intervention trial was carried out in seven pilot villages and seven control villages along Dongting Lake in Anxiang County, Hunan Province. Besides annual routine control measures such as synchronous chemotherapy, molluscicidal spray and health education, all buffaloes and sheep were killed or removed from the pilot areas in 2005, of which the effect was strengthened by other supporting measures such as replacing bovines by agricultural machines, isolating meadows and prohibiting pastures, supplying safe water, and building sanitary lavatories or methane pits. Schistosoma japonicum infection in humans or Oncomelania snails was observed and followed up to the spring of 2011. RESULTS: Three years after the intervention, the infection rates in humans decreased to below 1% with no infected snails found outside the embankment in the pilot villages, but the infection rates still ranged between 2% and 3% in the control villages 4 years after the intervention. The comprehensive measures centered on buffalo removal exempted about 50% of the population from the infection in pilot villages. CONCLUSION: Buffalo removal is the key element of comprehensive control strategy which could accelerate the control process and promote the elimination of schistosomiasis in lake and marshland regions along the Yangtze River.
