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