江滩型疫区人群日本血吸虫感染与再感染的前瞻性研究

A PROSPECTIVE COHORT STUDY ON HUMAN INFECTION AND REINFECTION WITH SCHISTOSOMA JAPONICUM IN RIVER BEACH AREA

目的 :研究江滩型日本血吸虫病中度流行区化疗后人群血吸虫感染、再感染及其危险因素。方法 :在观察试区 ,以 1 2 9例感染者经吡喹酮治疗后虫卵转为阴性的 1 2 6人为“再感染”研究对象 ;2 4 7例粪检阴性人群作为“感染”研究对象。追踪观察两组人群在一个感染季节后的再感染情况 ,并调查其接触疫水情况以及当地螺情和疫水变化情况等因素 ;再对其进行单因素分析和多因素非条件 logistic回归分析。结果 :基线感染率为 1 3 .3 7% ,经过一个感染季节后 ,标准化感染率为 4 .1 1 % ,标准化再感染率高达 1 3 .76% ,再感染率已恢复到化疗前人群感染水平 ,其中年龄≤ 1 2岁组再感染率 ( 2 2 .50 % )高于 >1 2岁组感染率 ( 9.3 0 % )。接触疫水处水体尾蚴密度、年龄、6～ 9月疫水接触指数、居住地距阳性螺点距离是再感染发生的主要危险因素。接触疫水处水体尾蚴密度、职业和 6～ 9月疫水接触指数是血吸虫病感染的主要危险因素 ,结论 :在日本血吸虫病中度流行区也存在较快感染和再感染趋势 。

Aim:To survey the human infection and reinfection with schistosomiasis japonica and the risk factors after chemotherapy in river beach meso endemic area Method: A prospective cohort study has been made in a village in river beach area of Dangtu County, Anhui Province from Feb to Dec 1998 126 egg negative cases after praziquantel treatment were allocated in reinfection group, while 247 egg negative individuals in pretreatment stool examination in infection group In May, September and December, infection or reinfection were identified by stool examination in each group and at the same time, risk factors were screened All the data were analysed with unconditional logistic regression analysis Results: After one transmission season, the prevalence of reinfection in the village reached 13 49% (standardized prevalence of reinfection 13 76%), and the infection rate 6 07% (standardized infection rate 4 11%) Stepwise logistic regression analysis showed that 4 factors i e cercaria density in water, age, index of contacting contagious water from June to September and distance between residence and infected snail spot were associated with reinfection, while cercaria density in water, occupation and index of contacting contagious water from June to September were associated with infection Conclusion: In meso endemic river beach area, higher frequency of reinfection and infection occurred and the risk factors were primarily screened out