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Widal Test Overview


The Widal Test’s propensity for erroneous results is obfuscating India’s typhoid burden, increasing expenses, and risking more antimicrobial resistance.


GS II: Science and technology

Widal Test Overview:

  • The Widal test is employed to diagnose typhoid fever, a bacterial infection caused by Salmonella Typhi, commonly transmitted through contaminated food or water.
  • Symptoms of typhoid fever include fatigue, high fever, headache, diarrhoea or constipation, abdominal pain, weight loss, and red spots, which overlap with other infections, complicating diagnosis without proper testing.
  • The test detects antibodies produced by the immune system against Salmonella Typhi in the patient’s blood sample.
  • It aids in diagnosing current or recent infections and determining previous exposure to typhoid.
  • Being a point-of-care test, it does not require specialized skills or infrastructure for implementation.
  • Developed in the late 1800s by a French physician, the Widal test has limitations and is no longer widely used due to its shortcomings, as highlighted by the World Health Organization (WHO).

Limitations of the Widal Test:

  • A single positive result does not definitively confirm a typhoid infection, nor does a negative result exclude it.
  • Diagnosis of an active infection typically requires testing of at least two serum samples taken 7-14 days apart to detect changes in antibody concentrations, which can be challenging and time-consuming.
  • In regions with a high typhoid burden, baseline antibody levels may be present, complicating result interpretation without established cutoff values.
  • Reagents used in the Widal test may cross-react with antibodies from other infections or vaccinations, leading to false positives.
  • Previous antibiotic therapy can alter antibody levels, potentially yielding false-negative results.

-Source: The Hindu


May 2024