Widal Test (Tube Method)

Widal Test (Tube Method)

Preferred Specimen(s) 3ml serum

Instructions Separate serum from cells as soon as possible

Transport Container No additive (red-top) tube

Transport Temperature Refrigerated, 48 hours

Reject Criteria

• Received frozen;
• Room temperature

Methodology Tube Method

Clinical Significance The Widal test is a presumptive serological test for Enteric fever or Undulant fever that may be caused by Salmonella infections (S. typhi, S. paratyphi A & B). The most important causative factor in India is S. typhi. The antibodies are tested against two types of antigens, the protein H (flagellar) and the polysaccharide O (somatic) antigen. The H antigen is a protein and more antigenic and hence gives higher antibody titers. The H antigen is however relatively nonspecific due to due to shared antigens amongst entero-bacteriaceae. The O polysaccharide antigen gives lower titers and is more specific. A twofold rise in titer is diagnostic of typhoid fever. A single reading of titer more than 240 is also considered as diagnostic.

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