Microbiology · Typhoid Fever
Widal Test – Typhoid Diagnosis
Detects antibodies against Salmonella typhi and paratyphi in blood. A standard part of the fever workup in India.
Diagnosing the "Enteric Fever" — Over a Century of the Widal Test
First described by Georges-Fernand Widal in 1896, the Widal test remains one of the most widely used typhoid diagnostic tools in India and other endemic regions. It works by mixing a patient's serum with suspensions of killed Salmonella typhi and Salmonella paratyphi antigens — if antibodies are present, visible clumping (agglutination) occurs, indicating typhoid exposure or active infection.
Typhoid fever is caused by Salmonella typhi, spread through contaminated food and water. It produces a characteristic step-ladder fever pattern over 1–4 weeks. The Widal test is most reliable after the 7th–10th day of illness when antibody titres have risen sufficiently to be detectable.
Antigens Tested
| Antigen | Organism | Significant Titre |
|---|---|---|
| S. typhi O | Salmonella typhi | ≥ 1:160 (active infection) |
| S. typhi H | Salmonella typhi | ≥ 1:160 |
| S. paratyphi AH | Salmonella paratyphi A | ≥ 1:80 |
| S. paratyphi BH | Salmonella paratyphi B | ≥ 1:80 |
* Significant titres vary by lab and region. Interpretation must always be made in the context of clinical symptoms and local endemic baseline.
Symptoms of Typhoid Fever
Preparation & Limitations
No preparation required. The Widal test is most reliable after 7–10 days of fever. It has limitations — false positives from prior vaccination, other salmonella infections, or endemic areas. For definitive diagnosis, blood culture remains the gold standard. Always interpret results with your doctor.
Test Price at Velys Hospital
₹150
Inclusive of collection · Same-day report
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Fever panel available · No fasting · Same-day results · Ahmedabad