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Field comparison of circulating antibody assays versus circulating antigen assays for the detection of schistosomiasis japonica in endemic areas of China

Cai, Yu-Chun, Xu, Jun-Fang, Steinmann, Peter, Chen, Shao-Hong, Chu, Yan-Hong, Tian, Li-Guang, Chen, Mu-Xin, Li, Hao, Lu, Yan, Zhang, Ling-Ling, Zhou, Yang, Chen, Jia-Xu
Parasites & vectors 2014 v.7 no.1 pp. 138
Schistosoma japonicum, blood serum, circulating antigens, cost effectiveness, diagnostic techniques, enzyme-linked immunosorbent assay, feces, hemagglutination, public health, schistosomiasis, screening, villages, China
BACKGROUND: Schistosomiasis remains a serious public health problem in affected countries, and routine, highly sensitive and cost-effective diagnostic methods are lacking. We evaluated two immunodiagnostic techniques for the detection of Schistosoma japonicum infections: circulating antibody and circulating antigen assays. METHODS: A total of 1864 individuals (between 6 and 72 years old) residing in five administrative villages in Hubei province were screened by serum examination with an indirect hemagglutination assay (IHA). The positive individuals (titer ≥20 in IHA) were reconfirmed by stool examination with the Kato-Katz method (three slides from a single stool specimen). Samples of good serum quality and a volume above 0.5 ml were selected for further testing with two immunodiagnostic antibody (DDIA and ELISA) and two antigen (ELISA) assays. RESULTS: The average antibody positive rate in the five villages was 12.7%, while the average parasitological prevalence was 1.50%; 25 of the 28 egg-positive samples were also circulating antigen-positive. Significant differences were observed between the prevalence according to the Kato-Katz method and all three immunodiagnostic antibody assays (P-value <0.0001). Similar differences were observed between the Kato-Katz method and the two immunodiagnostic antigen assays (P-value <0.0001) and between the antigen and antibody assays (P-value <0.0001). CONCLUSION: Both circulating antibody and circulating antigen assays had acceptable performance characteristics. Immunodiagnostic techniques to detect circulating antigens have potential to be deployed for schistosomiasis japonica screening in the endemic areas.