title: Comparison of a rapid diagnostic test and microimmunofluorescence assay for detecting antibody to Orientia tsutsugamushi in scrub typhus patients in China.
abstract: OBJECTIVE
  To evaluate the detection of IgM and IgG antibodies to Orientia tsutsugamushi (O. tsutsugamushi) by rapid diagnostic test (RDT) and microimmunofluorescence assay (mIFA).
  
  
  METHODS
  RDT using a mixture of recombinant 56-kDa proteins of O. tsutsugamushi and mIFA assay were performed on 20 patients from Fujian and 13 patients from Yunnan Province, and 82 sera samples from healthy farmers in Anhui Province and Beijing City in 2009. Comparison of the RDT and mIFA assay was performed by using X(2) test and the P level of <0.05 was considered to be significance.
  
  
  RESULTS
  Among these 82 normal sera samples, the specificity of RDT was 100% for both IgM and IgG tests. In 33 samples from patients with scrub typhus, 5 cases were positively detected earlier by RDT than by mIFA in IgM test, and 2 cases were positive in IgG test. Sensitivities of RDT were 93.9% and 90.9% for IgM and IgG, respectively. The sensitivity of combination test of IgM and IgG was 100%. Geometric mean titer diluted sera from confirmed cases by IFA and RDT assay were 1:37 vs. 1:113 (P<0.001) in IgM test and 1:99 vs. 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.
authors.affiliation: Department of Rickettsiology, National Institute of Communicable Disease Control and Prevention, China CDC, Changping, Beijing, China. zhanglijuan@icdc.cn
authors.forename: Lijuan
authors.initials: L
authors.lastname: Zhang
authors.forename: Si
authors.initials: S
authors.lastname: He
authors.forename: Shiwen
authors.initials: S
authors.lastname: Wang
authors.forename: Huilan
authors.initials: H
authors.lastname: Yu
authors.forename: Xuemei
authors.initials: X
authors.lastname: Li
authors.forename: Derong
authors.initials: D
authors.lastname: Zhang
authors.forename: Lei
authors.initials: L
authors.lastname: Pan
authors.forename: Qiang
authors.initials: Q
authors.lastname: Yu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood* / Q000276:immunology; D001426:Bacterial Proteins / Q000097:blood / Q000276:immunology; D002648:Child; D002681:China; D003955:Diagnostic Tests, Routine; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology; D007075:Immunoglobulin M / Q000097:blood* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D012285:Orientia tsutsugamushi / Q000254:growth & development / Q000276:immunology*; D011994:Recombinant Proteins / Q000097:blood / Q000276:immunology; D012612:Scrub Typhus / Q000175:diagnosis* / Q000276:immunology / Q000473:pathology; D012680:Sensitivity and Specificity
chemical_list: D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D011994:Recombinant Proteins