安徽省血吸虫病潜在流行区疫情输入的风险评估

Risk evaluation of schistosomiasis japonica input to potential endemic areas in Anhui province

目的 分析“引江济淮”工程对血吸虫病流行的影响,评估安徽省血吸虫病潜在流行区巢湖地区疫情输入与传播的风险.方法 2008-2012年在安徽巢湖地区设立1个固定监测点和3个流动监测点,分别于2008年和2012年秋季对固定监测点常住居民进行血吸虫感染情况调查,共检测615名.于2008-2012年每年秋季对流动监测点流动人口进行血吸虫感染情况调查,共调查1603名,先采用间接红细胞凝集试验（IHA）进行血清学检测,血检阳性者再采用集卵沉淀法进行病原学检查.同期,采用塑料杯顶管孵化法对固定监测点和对巢湖地区当年从流行区购进的家畜进行血吸虫感染情况调查,共调查303头.2008-2012年在巢湖地区危险地带和可疑环境开展钉螺分布情况调查,并在巢湖通江河道打捞漂浮物开展钉螺扩散调查.2007-2010年采用螺笼放养法,对钉螺在巢湖生存繁殖的可能性进行实验研究.结果 2008年和2012年采用IHA分别检查巢湖地区当地居民301和314名,未发现阳性.2008-2012年采用IHA检查巢湖地区流动人口1603名,阳性率为3.1％（49/1603）;采用集卵沉淀法检查流动人口75名,27例阳性.采用塑料杯顶管孵化法检查巢湖当地和从流行区购进的家畜共303头,未发现阳性.在巢湖地区危险地带和可疑环境分别调查1630和3551 km2,均未发现钉螺;在巢湖通江河道打捞漂浮物457.6 kg,发现有11只钉螺附着.2007-2010年钉螺在巢湖2个实验区的存活率分别为88％（86/98）、51％ （45/89）、30％（25/71）、24％ （20/84）和92％（85/92）、54％（50/92）、23％（12/52）、17％（13/79）,与对照区钉螺存活率[96％（85/89）、52％ （44/85）、26％（18/69）、18％（14/76）]差异均无统计学意义（x2值分别为3.78、0.27、2.51、1.50,P值均＞0.01）;2008-2010年每年均在实验区和对照区均检获了子代钉螺,数量为156～312只.结论 巢湖地区已发现输入性血吸虫病传染源,外源性钉螺向巢湖扩散并生存繁殖的可能性较大,安徽省血吸虫病潜在流行区疫情输入与传播的风险较高.

Objective To analyze the impact of water transfer project from the Yangtze River to the Huaihe River on schistisomiasis transmission,and to evaluate the risk of the disease input to the potential endemic area in Anhui Province,namely the Chaohu Lake region.Methods From 2008 to 2012,1 fixed and 3 mobile surveillance sites in the Chaohu Lake area were selected,and the schistosomiasis infection situation of 615 local residents in the fix surveillance site was investigated in autumns of 2008 and 2012,while the schistosomiasis infection situation of 1603 mobile population in the 3 mobile surveillance sites were investigated in autumns of 2008 to 2012.All people were screened by indirect hemagglutination assay （IHA）,and the positive ones were then examined by sedimentation method.303 local livestock and livestock from schistosimiasis endemic areas were examined by stool hatching method in autumns of 2008 to 2012.From 2008 to 2012,the distribution of Oncomelania snails was investigated in risk areas and suspicious areas,and the snail spreading pattern was conducted through salvaging floaters in rivers connected with the Yangtze River.In addition,the Oncomelania snails were raised in the cages on the beaches of the Chaohu Lake,a control area,from 2007 to 2010,and their survival and reproduction capacity was observed.Results In 2008 and 2012,301 and 314 local residents were detected by IHA,but there were no positive found.From 2008 to 2012,a total of 1603 mobile population were examined by IHA,and the positive rate of antibody was 3.1％ （49/1603） ; 75 individuals were examined by sedimentation method,and the positive rate was 36.00％ （27/75）.A total of 303 livestock were examined by stool hatching method,but no one showed positive.A total of 1630 km2 in risk areas and 3551 km2 in suspicious areas were surveyed,but there were no Oncomelania snails found.A total of 457.6 kg floating debris were investigated,and 11 Oncomelania snails were found.From 2007 to 2010,the survival rate of Oncomelania snails in two trail areas in the Chaohu Lake and in the control area was 88％ （86/98）,51％ （45/89）,30％ （25/71）,24％ （20/84） and 92％ （85/92）,54％ （50/92）,23％ （12/52）,17％ （13/79） and 96％ （85/89）,52％ （44/85）,26％ （18/69）,18％ （14/76）,respectively,there were no statistical significance between the trial areas and the control area （x12 =3.78,P＞0.01; x22 =0.27,P＞0.01; x32 =2.51,P＞0.01; x42 =1.50,P＞ 0.01）,and filial generation snails were found in each observation area from 2008 to 2010,the number was 156-312.Conclusion The imported infectious sources of schistosomiasis have been found in the Chaohu Lake region,the possibility of imported exogenous Oncomelania snails spreading into the Lake and surviving and reproducing there is high.The risk of schistosomiasis input to the potential endemic area in Anhui Province is predicted to be high.