WIDAL TEST - SCI &
TECH
News: How the Widal test is clouding
India’s sense of its typhoid problem | Explained
What's in the news?
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The Widal Test's susceptibility to producing
inaccurate results is obscuring the true extent of India's typhoid burden,
leading to heightened healthcare costs and amplifying the risk of antimicrobial
resistance.
Widal Test:
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The Widal test is utilized for diagnosing typhoid fever, also known as enteric fever, caused by the bacterium Salmonella Typhi.
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This bacterial infection is commonly transmitted
through contaminated food or water.
Symptoms and Challenges
of Typhoid Fever Diagnosis:
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Symptoms of typhoid fever include fatigue, high
fever, headache, diarrhea or constipation, abdominal pain, weight loss, and red
spots.
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These symptoms overlap with those of other diseases
such as malaria, dengue, influenza, and typhus, complicating diagnosis without
proper testing.
Principle and
Application of the Widal Test:
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The Widal test is a serological test that detects antibodies against Salmonella Typhi
in a patient's blood sample.
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It aids in diagnosing current or recent infections
and determining past exposure to typhoid bacteria.
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As a point-of-care test, it doesn't require
specialized skills or infrastructure.
Historical Background
and Current Usage:
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Developed in the late 1800s by a French physician,
the Widal test is still employed in some regions for diagnosing typhoid fever.
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However, its usage has declined in many countries
due to its limitations and flaws.
Limitations of the Widal
Test:
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A single positive Widal test result doesn't confirm
the presence of typhoid infection, and a negative result doesn't rule it out.
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Diagnosis of an active infection requires testing
at least two serum samples taken 7-14 days apart, which is often impractical.
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In areas with high typhoid prevalence, baseline
antibody levels may confound test interpretation.
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Cross-reactivity of test reagents with antibodies
from other infections or vaccination can lead to false positives.
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Prior antibiotic therapy may impact antibody
levels, resulting in false negatives.