[Assessment of effect and quality control for parasitological tests in national schistosomiasis surveillance sites]

To understand the ability of pathogenic diagnosis for schistosomiasis japonica in the national surveillance sites and evaluate the effect of stool hatching method in the field, so as to provide the evidence for establishing a quality control system of pathogenic diagnosis of schistosomiasis in the surveillance sites.

The data pertaining to the parasitological diagnosis of the residents with positive serological tests were collected in 81 national surveillance sites of 12 provinces in 2011, and the effects of the Kato-Katz technique and stool hatching method were evaluated and compared. The incubation quality control samples made by the national schistosomiasis diagnosis reference laboratory were detected by both Kato-Katz technique and stool hatching method using the single-blind method, and the results were analyzed and compared for the coincidence rate, misdiagnosis rate and missing diagnosis rate in all the county laboratories in 2012.

A total of 3 780 sero-positive residents were tested by using the Kato-Katz technique and stool hatching method in the 81 national surveillance sites in 2011, 127 persons were double egg-positive, 3 513 persons were double egg-negative, and the total coincidence rate was 96.30%. Totally 173 infected people were diagnosed by using the Kato-Katz technique and the positive detection rate was 4.58%; 221 infected people were diagnosed by using the stool hatching method and the positive detection rate was 5.85%. A total of 267 positive people were diagnosed by the Kato-Katz technique or the stool hatching method or both and the total positive detection rate was 7.06%, which was higher by 54.15% than that by using the single Kato-Katz technique (chi2 = 21.32, P < 0.01). In 2012, of 240 standard incubation quality control samples (160 positives, 80 negatives) detected by the technicians from the 80 surveillance sites, 105 samples were positive and 67 samples were negative, with a total coincidence rate of 71.67% (172/240) and a total missing diagnosis rate of 34.38% (55/160). Among them, the missing rate of the strong positive samples was 32.50% (26/80), the missing rate of the weakly positive samples was 36.25% (29/80), and the misdiagnosis rate of the negative samples was 16.25% (13/80). The detection rates of the incubation quality control samples were 61.11%, 80.00%, 77.08%, 90.48%, 58.33% and 59.26% in the surveillance sites of six provinces, including Anhui, Hubei, Hunan, Jiangsu, Jiangxi and Sichuan provinces, respectively, and a significant difference was found (chi2 = 14.27, P < 0.05).

The detection efficiency of the stool hatching method is superior to that of the Kato-Katz technique in the field. However, the levels of the technical personnel for the stool hatching method are relatively low in most of the surveillance sites. Therefore, the technical training should be strengthened.