Comparison of a rapid diagnostic test and microimmunofluorescence assay for detecting antibody toOrientia tsutsugamushi in scrub typhus patients in China

摘要

Objective:To evaluate the detection of IgM and IgG antibodies toOrientia tsutsugamushi(O. tsutsugamushi) by rapid diagnostic test(RDT) and microimmunofluorescence assay (mIFA). Methods:RDT using a mixture of recombinant56-kDa proteins ofO. tsutsugamushi and mIFA assay were performed on20 patients from Fujian and 13 patients from Yunnan Province, and82 sera samples from healthy farmers in Anhui Province and Beijing City in 2009. Comparison of the RDT and mIFA assay was performed by usingχ2 test and theP level of<0.05 was considered to be significance.Results:Among these82 normal sera samples, the specificity of RDT was 100% for both IgM and IgG tests. In33samples from patients with scrub typhus,5 cases were positively detected earlier byRDT than by mIFA in IgM test, and 2 cases were positive in IgG test. Sensitivities ofRDT were 93.9% and90.9% for IgM and IgG, respectively. The sensitivity of combination test of IgM and IgG was 100%. Geometric mean titer diluted sera from confirmed cases byIFA andRDT assay were 1÷37vs. 1÷113 (P<0.001) in IgM test and1÷99vs. 1÷279 (P<0.05) in IgG test.Conclusions:RDT is more sensitivite than mIFA in the early diagnosis of scrub typhus and it is particularly applicable in rural areas.