湘江流域某市,湘江穿城而过,江中有一绿色小洲,该洲长约2000米,宽约500米,洲面西高东低,高的部分为居民居住地和蔬菜地,有居民146户、422人;洲面低的部分树木成林、杂草丛生,常年冬陆夏水,是市民特别是青少年休闲娱乐的场所。该市及该洲历年未见血吸虫病流行记载。1997年9月,因 A city in the Xiangjiang River valley runs through the city and passes through the city. There is a green small continent in the river. The continent is about 2,000 meters long and 500 meters wide. The western part of the Zonjong is low and high in the east, with residential and vegetable areas and residents 146 Households, 422 people; part of the low surface area Chau forest, overgrown, perennial winter Lu summer water, is the public, especially young people entertainment places. The city and the continent over the years have not seen schistosomiasis epidemic records. September 1997, because