【摘要】 目的　用流行病学方法确定易感者和拮抗者 ,为日本血吸虫再感染的年龄依赖性抗性提供依据。方法　 1996年 ,选择南洞庭湖日本血吸虫病洲岛型流行区经常接触疫水的居民 2 5 0人作为研究对象 ,行吡喹酮顿服治疗。随后 ,观察了研究对象日常接触疫水情况 141d,暴露指数以平均每天接触疫水皮肤面积 (m2 )与时间 (min)的乘积 (m2 · min/ d)计 ,并对其行四次方根标准化换算。1998年 ,其中 2 13人接受了粪检 ,并根据粪检结果和疫水接触程度对 2 13名对象进行流行病学易感和拮抗的分类。结果　 1998年 ,感染率为 2 3.0 % ,感染度 (EPG)几何均值为 6 4.5 ;感染率在低年龄组 (<10岁 )人群中最高 ,并随年龄的增加而递减 ;在感染人群中 ,男性感染率和感染度均高于女性 (P <0 .0 1)。 2 13名对象可分为 3组 :易感组 (2 3.0 % )、抗性组 (13.6 % )和不确定组 (6 3.4% ) ;平均暴露指数换算值为 6 .2 m2· min/ d,男性高于女性。年龄组的暴露指数和治后再感染度之间存在剪刀差关系。结论　本研究表明 ,流行区人群治后存在对日本血吸虫再感染年龄依赖性抗性。更多还原

【Abstract】 Objective To identify potentially immunogenetically informative individuals on the basis of epidemiological susceptibility or resistance to S.japonicum infection and provide further evidence for age-dependent resistance to reinfection to S.japonicum. Methods After a cross-section survey in 1996,250 individuals (subjects) living in the two islands (Qingshan and Yanjiashan) of Dongting Lake region were selected for praziquantel treatment and a 2-year follow-up study. In 1998,213 of the 250 subjects provided stool samples for final assessment. Surface water contact was measured over a 2-year period for 141 days from activity diaries,and expressed as m2-mins of skin exposure per day. Mean exposure for groups was calculared by detransforming the mean of fourth-root-transformed (normalized) m2-min/d. Results In 1998,the reinfection rate was 23% and the geometric mean intensity of infected subjects was 64 5 epg.Reinfection peaked in subjects aged below 10 years and then declined as age increased. Males had a higher rate of reinfection and intensity among those infected than females (P<0 01).Two hundred and thirteen of the 250 individuals were classified into three groups:susceptibles (23 0%),insusceptibles (13 6%) and uncertain status (63 4%). The 213 individuals had a mean exposure (detransformed) to surface water of 6 2 m2·min/d with males having a higher mean water exposure than that with females. There was an inverse association between age-specific exposure and age-specific reinfection intensity. Conclusion This study supported a hypothesis that there existed an age-dependent resistance to reinfection of S.japonicum in population in endemic areas of schistosomiasis japonica.更多还原