[Effectiveness of routinely used assays for the diagnosis of schistosomiasis japonica in the field].

OBJECTIVE

To evaluate the effectiveness of routinely used assays for schistosomiasis diagnosis in the field.

METHODS

From late November to early December 2005, 6-65 years old inhabitants from 3 endemic villages were examined by Kato-Katz technique (3 thick smears) and nylon bag sedimentation/hatching method. At the same time, dipstick dye immunoassay(DDIA), fast enzyme linked immunosorbent assay (F-ELISA), indirect haemagglutination test A (IHA-A) and B ( IHA-B) were carried out in parallel

RESULTS

1864 people were examined by stool examination with an average positive rate of 9.7%. The missing rate of DDIA was relatively stable in medium and heavily endemic areas of schistosomiasis. The missing rate of nylon bag sedimentation/hatching method was 25% and relatively stable when the number of eggs per gram of feces(EPG) was larger than 100. The average positive rate of DDIA, F-ELISA, IHA-A and IHA-B was 47.8%, 50.0%, 66.3% and 40.1% respectively. Using stool examination as the gold standard, the sensitivity of DDIA, F-ELISA, IHA-A and IHA-B was 75.3%, 65.8%, 85.6% and 76.0%; and the specificity was 55.1%, 51.7%, 35.7% and 63.6%, respectively. Among the four sero-diagnostics, the specificity, Youden index, positive likelihood rate and coincidence of IHA-B were the highest.

CONCLUSION

Kato-Katz method is more stable and effective than nylon bag sedimentation/hatching method in medium and heavily endemic areas of schistosomiasis japonica. The sensitivity and specificity of these four diagnosis kits are lower than 90%.