title: Comparison of the Performance of the TPTest, Tubex, Typhidot and Widal Immunodiagnostic Assays and Blood Cultures in Detecting Patients with Typhoid Fever in Bangladesh, Including Using a Bayesian Latent Class Modeling Approach.
abstract: BACKGROUND
  There is an urgent need for an improved diagnostic assay for typhoid fever. In this current study, we compared the recently developed TPTest (Typhoid and Paratyphoid Test) with the Widal test, blood culture, and two commonly used commercially available kits, Tubex and Typhidot.
  
  
  METHODS
  For analysis, we categorized 92 Bangladeshi patients with suspected enteric fever into four groups: S. Typhi bacteremic patients (n = 28); patients with a fourfold change in Widal test from day 0 to convalescent period (n = 7); patients with Widal titer ≥1:320 (n = 13) at either acute or convalescent stage of disease; and patients suspected with enteric fever, but with a negative blood culture and Widal titer (n = 44). We also tested healthy endemic zone controls (n = 20) and Bangladeshi patients with other febrile illnesses (n = 15). Sample size was based on convenience to facilitate preliminary analysis.
  
  
  RESULTS
  Of 28 S. Typhi bacteremic patients, 28 (100%), 21 (75%) and 18 (64%) patients were positive by TPTest, Tubex and Typhidot, respectively. In healthy endemic zone controls, the TPTest method was negative in all, whereas Tubex and Typhidot were positive in 3 (15%) and 5 (25%), respectively. We then estimated sensitivity and specificity of all diagnostic tests using Bayesian latent class modeling. The sensitivity of TPTest, Tubex and Typhidot were estimated at 96.0% (95% CI: 87.1%-99.8%), 60.2% (95% CI: 49.3%-71.2%), and 59.6% (95% CI: 50.1%-69.3%), respectively. Specificity was estimated at 96.6% (90.7%-99.2%) for TPTest, 89.9% (79.6%-96.8%) for Tubex, and 80.0% (67.7%-89.7%) for Typhidot.
  
  
  CONCLUSIONS
  These results suggest that the TPTest is highly sensitive and specific in diagnosing individuals with typhoid fever in a typhoid endemic setting, outperforming currently available and commonly used alternatives.
authors.affiliation: Centre for Vaccine Sciences, International Centre For Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: Kamrul
authors.initials: K
authors.lastname: Islam
authors.affiliation: Centre for Vaccine Sciences, International Centre For Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: Md Abu
authors.initials: MA
authors.lastname: Sayeed
authors.affiliation: Centre for Vaccine Sciences, International Centre For Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: Emran
authors.initials: E
authors.lastname: Hossen
authors.affiliation: Centre for Vaccine Sciences, International Centre For Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: Farhana
authors.initials: F
authors.lastname: Khanam
authors.affiliation: Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, United States of America.|Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Richelle C
authors.initials: RC
authors.lastname: Charles
authors.affiliation: Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Jason
authors.initials: J
authors.lastname: Andrews
authors.affiliation: Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, United States of America.|Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America.|Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America.
authors.forename: Edward T
authors.initials: ET
authors.lastname: Ryan
authors.affiliation: Centre for Vaccine Sciences, International Centre For Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors.forename: Firdausi
authors.initials: F
authors.lastname: Qadri
mesh_terms: D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000097:blood*; D001459:Bangladesh; D001499:Bayes Theorem; D001769:Blood / Q000382:microbiology; D005260:Female; D006801:Humans; D007159:Immunologic Tests / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010284:Paratyphoid Fever / Q000175:diagnosis; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D014435:Typhoid Fever / Q000175:diagnosis* / Q000382:microbiology
chemical_list: D000907:Antibodies, Bacterial; D011933:Reagent Kits, Diagnostic