ELISA与IHA在血吸虫病不同流行程度地区的现场筛查效果评价

Evaluation of screening effects of ELISA and IHA techniques in different epidemic areas of schistosomiasis

目的评价与比较ELISA法和IHA法在血吸虫病不同流行程度地区的筛查效果。方法选择四个日本血吸虫病流行程度不同的试点村,对5～65岁适检人群进行Kato-Katz法(二送三检)、ELISA法、IHA法等3种方法平行检测。结果ELISA法的敏感度和特异度分别为96.05%、95.74%,IHA分别为89.74%、100%。但两种方法现场“特异度”较低(ELISA:43.21%￣92.17%;IHA:67.56%～91.55%),且其阳性预测值亦较低(ELISA法:3.1%￣18.6%;IHA:2.9%￣15.8%)。两法平行检测比较:两者的测定值具有一定的相关性(r=0.767,P<0.01),但IHA法阳性阈值(1∶10)对应的OD值高于ELISA阳性阈值水平(0.105),在0.124￣0.308左右。在疫情相对较重的地区,ELISA法阳性率高于IHA,其阳性预测值低于IHA;在疫情相对轻的地区,两法阳性率、阳性预测值无显著性差异。结论在血吸虫病疫情未控制地区,IHA法现场筛查效果相对优于ELISA法,但两者均存在假阳性率较高、阳性预测值较低的缺陷。

Objective To evaluate and compare the screening effects of ELISA and IHA techniques in different epidemic areas of schistosomiasis japanica. Methods Four villages,with different epidemicity of schistosomiasis,were selected as fields, of which every subject was examined with kato-katz, ELISA and IHA techniques simultaneously. Results The sensitivity and specificity of ELISA and IHA were very high （ELISA： 94.87%, 95.74%; IHA：89.74%,100%） . But the field-based detection indicated that the specificity of two serological techniques was relatively low （ELISA：43.21%~92.17%;IHA：67.56%～91.55%）, and the PPV were remarkly low as well（ELISA：3.1%~18.6%;IHA：2.9%~15.8%）. The result of the parallel detection showed that the detection values between ELISA and IHA were significantly correlating（r=0.767,P〈0.01）, but the corresponding OD （optical density） value of the threshold value of IHA （1：10）, about 0.124~0.308, was higher than the threshold of ELISA （0.105）. The positive predictive value （PPV） as well as positive rate of IHA was significantly higher than ones of ELISA in the higher endemicity villages, and no significant difference with ELISA in the lower endemicity villages. Conclusion In an endemic area of schistosomiasis, the screening effects of IHA relatively outweigh ELISA, but there was a common drawback for two serological techniques, that is, the PPV were quite low in field investigation.