title: Evaluation of a newly developed ELISA against Widal, TUBEX-TF and Typhidot for typhoid fever surveillance.
abstract: BACKGROUND
  Typhoid fever is endemic in many parts of the world and represents a major cause of acute febrile illness (AFI). Rapid and accurate laboratory methods for diagnosis of this disease are needed for both patient care and surveillance situations.
  
  
  METHODS
  Serum samples were collected from AFI patients and used to evaluate the performance of a newly developed ELISA assay that uses a mixture of somatic and flagellar antigens to detect the total antibody response against Salmonella enterica subspecies enterica serovar Typhi (S. Typhi) infection. The levels of Ig isotype response (IgG, IgM and IgA) were also evaluated, and results were compared to those of TUBEX-TF and Typhidot commercial kits.
  
  
  RESULTS
  Of 234 culture-confirmed typhoid patients, the total Ig ELISA diagnosed 93% compared to 71% using Widal test. This sensitivity level (93%) is higher than that observed for the individual Ig ELISAs (IgG 75%; IgM 79%; IgA 57%) and the commercial tests TUBEX-TF (75%), Typhidot IgM (63%) and Typhidot IgG (28%). An agreement of 78% was achieved between the total Ig ELISA and Widal test. The average specificity of the ELISA was 96%. Using ELISA, up to 200 samples can be tested per run with cost per test at US$0.20.
  
  
  CONCLUSIONS
  The developed ELISA shows superior sensitivity and specificity, when compared to Widal, TUBEX-TF and Typhidot assays, is more cost effective and allows higher throughput. This method is highly recommended for active surveillance studies or outbreak investigations of typhoid fever.
authors: US Naval Medical Research Unit No 3 NAMRU-3, Cairo, Egypt. moustafa.abdelfadeel.eg@med.navy.mil
authors: Moustafa Abdel
authors: MA
authors: Fadeel
authors: Brent L
authors: BL
authors: House
authors: Momtaz M
authors: MM
authors: Wasfy
authors: John D
authors: JD
authors: Klena
authors: Engy E
authors: EE
authors: Habashy
authors: Mayar M
authors: MM
authors: Said
authors: Mohamed Abdel
authors: MA
authors: Maksoud
authors: Bassem Abdel
authors: BA
authors: Rahman
authors: Guillermo
authors: G
authors: Pimentel
mesh_terms: D000328:Adult; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial; D019411:Clinical Laboratory Techniques / Q000379:methods*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D012485:Salmonella typhi / Q000276:immunology; D012680:Sensitivity and Specificity; D014435:Typhoid Fever / Q000175:diagnosis*
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M