title: Detection of Salmonella typhi agglutinins in sera of patients with other febrile illnesses and healthy individuals.
abstract: OBJECTIVE
  Widal test is frequently applied for the detection of Salmonella agglutinins to diagnose Salmonella enterica serotype Typhi infection. There are however a number of controversies challenging the diagnostic utility of this test. This study was performed to determine the prevalence of Salmonella agglutinins in patients with other febrile illnesses and healthy blood donors.
  
  
  METHODS
  Sera from 50 healthy blood donors were compared for the presence of Salmonella agglutinins in various groups of patients with other febrile illnesses using Widal test in the division of Serology and Immunology at King Khalid University Hospital, Riyadh. The patient groups of other febrile illnesses included infections with Beta-hemolytic streptococcus (n = 50), Brucella (n = 46), Helicobacter pylori (n = 24), Treponema pallidum (n = 30), Toxoplasma (n = 44), and other parasites (n = 20).
  
  
  RESULTS
  Majority of the patients and normal individuals were tested positive for Widal test at dilution of less than 1 : 40 both for the O (62.5%) and H (64.6%) antigen. A decreasing trend in Widal reactivity was observed with increasing dilutions of the serum samples. At 1 : 160 titer, which is generally considered as a cut off point for positive Widal test, 6.4 and 11% individuals had positive Widal test for O and H Salmonella antigens, respectively.
  
  
  CONCLUSIONS
  Detection of a significant number of positive Widal tests in conditions where it is expected to be nonreactive appears to be a serious problem in making a correct diagnosis of typhoid fever, thus challenging the diagnostic utility of the Widal test.
authors.affiliation: Department of Pathology, King Saud University & King Khalid University Hospital, Riyadh, Saudi Arabia. ali.somily@gmail.com
authors.forename: Ali M
authors.initials: AM
authors.lastname: Somily
authors.forename: Mustafa H
authors.initials: MH
authors.lastname: Adam
authors.forename: Mohamed O
authors.initials: MO
authors.lastname: Gad El Rab
authors.forename: Muhammad G
authors.initials: MG
authors.lastname: Morshed
authors.forename: Zahid
authors.initials: Z
authors.lastname: Shakoor
mesh_terms: D000328:Adult; D000372:Agglutination Tests / Q000379:methods*; D000907:Antibodies, Bacterial / Q000097:blood*; D000942:Antigens, Bacterial / Q000276:immunology*; D016022:Case-Control Studies; D005189:False Positive Reactions; D005260:Female; D005334:Fever / Q000097:blood* / Q000209:etiology / Q000276:immunology; D006785:Hospitals, University; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012016:Reference Values; D012485:Salmonella typhi / Q000276:immunology* / Q000302:isolation & purification; D012529:Saudi Arabia / Q000453:epidemiology; D012680:Sensitivity and Specificity; D014435:Typhoid Fever / Q000175:diagnosis* / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial