Abstract: Han Yan, Wei Wanhui, Yin Yueping, David Anderson, Wang Hongchun, Mary L Garcia, Huy Van, Zhu Xiaoyu, Chen Kai, Chen Xiangsheng Reference Laboratory of STD, National Center for STD Control, China CDC; Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing 210042, China （Han Y, Wei WH, Yin YP, Wang HC, Zhu XY, Chen K）, National Center for STD Control （Chen XS）; Macfarlane Burnet Institute for Medical Research and Practical Action, Melbourne 3004, Australia （Anderson D, Garcia ML, Van H） Corresponding author: Yin Yueping, Email: yinyp@ncstdlc.org 【Abstract】 Objective To evaluate the application of Burnet Institute-made prototype IgA rapid test, a kind of point-of-care （POC） testing, in the diagnosis of early syphilis. Methods Totally, 455 stored serum samples in the Reference Laboratory of Sexually Transmitted Disease, the Institute of Dermatology were used to evaluate the application of the prototype IgA rapid test （IgA-POC） in the diagnosis of early syphilis. According to resluts of Treponema pallidum hemagglutination assay （TPHA）, rapid plasma reagin card test （RPR）, and enzyme-linked immunosorbent assay for IgM antibodies （IgM-ELISA）, these stored samples were divided into 3 groups: uninfected group, previously infected group and early active syphilis group. IgA-POC test was performed in the 3 groups to evaluate its diagnostic performance for active syphilis, and researchers were blind to the group information. Results The prototype IgA-POC test had a sensitivity of 92.6% （147/163） for the early active syphilis group, a specificity of 72.22% （104/144） for the previously infected group, and a specificity of 97.97% （145/148） for the uninfected group. The total specificity of the prototype IgA-POC test was 85.27%, which met the minimum requirement of WHO for the POC test. The prototype IgA-POC test showed a significantly higher sensitivity for the diagnosis of early active syphilis compared with the IgM-ELISA （59.51%, Z = 6.88, P < 0.05）, but a significantly lower specificity for the diagnosis of previous syphilis infection compared with the IgM-ELISA （98.61%, Z = 6.18, P < 0.05）. Moreover, no significant difference in the specificity for the diagnosis of non-infection was observed between the prototype IgA-POC test and IgM-ELISA （Z = 1.16, P = 0.25）. Conclusion The prototype IgA-POC test has better capacity for the diagnosis of early active syphilis compared with the IgM-ELISA, so it can be applied to the screening of early active syphilis.

Key words: Syphilis, Syphilis serodiagnosis, Point of care testing