XU Xingjian, DAI Yuhai, WEI Fonghua
and YANG Xianxiang
Hubei Institute of Schistosomiasis
Control, Wuhan 430070, e-mail: xjxu@public.wh.hb.cn
Aim: To investigate major ecological environmental factors that might affect the transmission of Schistosoma japonicum in Jiang Han Plain of Hubei province following the Three Gorges Dam project on the Yangtze River in China, and to provide the relevant countermeasures of schistosomiasis control.
Methods: Data on the water level of the Yangtze River, riparian water table, annual rainfall and yearly evaporation were collected by means of field surveys and observation. Meanwhile, the snail distribution and schistosomiasis prevalence of human were investigated and analyzed with statistics method.
Results: After construction of the dam, the middle water level of the Yangtze River will last a longer period in the flood season, the fluctuation of riparian water table will follow the water level of the Yangtze River up and down. The prevalence of the people and snail density differed significantly between years which were correlate with high, middle and low typical water levels in the Yangzte, and it has a liner regression relationship between the prevalence of the people and the density of the snail with the depth of the water level, annual rainfall, yearly evaporation and ground altitude in the survey area. It has been confirmed the range of the water table is affected within 15 km along with the Yangtze River in flood season and 7 km in the low-water season. The endemic area of Hubei province has 52 cities or counties, of which 25 cities are along the Yangtze River. The snail area and infected people in 25 cities were 61.1% and 63.7% of whole province respectively in 1996.
Conclusion:
The impact of schistosomiasis transmission in Jiang Han Plain
following the Three Gorges Dam project is 1) on the positive aspect,
the enlargement of endemic area and the rise of prevalence of
schistosomiasis due to flood disaster would be controlled or reduced
after three gorges dam project completed. 2) on the negative aspect,
because of the change of the water level in the Yangtze River,
the riparian water table would be supplied by the side of the
river, which will lead to increase the area of low land in Jian
Han Plain. This situation might enlarge the snail habitats and
the range of schistosomiasis transmission in this area after Three
Gorges Dam project completed.
* Supported by UNDP/WORLD BANK/WHO Special Program for Research
and Training in Tropical Diseases (TDR) and Ministry of Health
in China.
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created 21/12/00
