成虫切片间接免疫酶染法诊断隐性血吸虫病的探讨

用血吸虫成虫冰冻切片间接免疫酶染法(IIP-AWA)检测血清抗血吸虫成虫抗体(AWAb)。5年前已消灭血吸虫病的上海县COPT阳性血清229份和有治疗史COPT阴性血清135份的阳性率各为96.9％和5.2％;122份粪检阳性患者血清均为强阳性;80份健康人血清均阴性。阳性血清滴度≥1:16时,成虫切片多数呈全虫弥漫型显色。149例血清阳性者经吡喹酮治疗后的阴转率,1年内IIP-AWA为80％,明显高于COPT(60.1％);2.5年两者无差别(85.5％与83.6％)。未转阴者滴度明显下降,染色多呈局限型(肠管显色)。表明血清AWAb阳性者,体内可能仍有成虫残存。本法对清查隐性血吸虫病患者(轻度感染,无临床表现者)有实用价值。

INDIRECT IMMUNOPEROXIDASE STAINING TECHNIQUE WITH FROZEN SECTIONS OF SCHISTOSOME FOR SERODIAGNOSIS OF LATENT SCHISTOSOMIASIS

Indirect immunoperoxidase staining technique using frozen sections of adult worm as antigen (IIP-AWA) was carried out to detect antibodies against schistosome antigens (AWAb) for the diagnosis of existing infection of schistosomiasis in COPT positive cases. Sera from 229 COPT positive and 135 COPT negative cases in Shanghai County, where schistosomiasis had been eradicated for more than 5 years, were tested. Sera from 122 patients with positive stool hatching from an endemic area were served as positive controls. The positive rates of the three groups were 96.9%, 5.2%, and 100% respectively. The staining pattern of the worm sections was mainly diffused at serum dilutions 1:4 to 1:16. 149 sero-positive cases were treated with pyquiton (60 mg/kg.2d) and re-examined 1, 1.5, and 2.5 years post-treatment. The negative conversion rate of IIP-AWA was considerably higher than that of COPT (80% vs. 61.1%) at the first year, but no significant difference was observed after 2.5 years (85.5% vs. 83.6%). With the decreasing antibody titer, the staining pattern of worm sections changed from diffused to focal pattern, mostly in the gut. The results suggest that the presence of detectable AWAb in untreated patients or patients treated 2 years ago with pyquiton possibly indicate latent schistosomiasis. IIP-AWA is of practical value in screening populations for latent schistosomiasis in areas where the disease had been under control.