Widal Test (Typhoid)

What is the Widal Test?

The Widal test is a serological assay that detects antibodies (agglutinins) against the Salmonella Typhi and Salmonella Paratyphi bacteria, the organisms that cause typhoid and paratyphoid fevers. It is performed on a blood sample and gives a titre (antibody level) that can suggest recent or past infection.

Key Parameters

Why is it done?

• To investigate a patient with fever, abdominal pain, or other signs that could be typhoid.
• To support a clinical diagnosis when symptoms are typical but other tests are pending.
• In some settings, to monitor the response to treatment in a confirmed case.

Early Detection

The test can help identify signs of typhoid or paratyphoid infection, but it does not diagnose the disease on its own. A doctor interprets the result together with symptoms, history, and other laboratory findings.

What an abnormal result may mean

• High titres may indicate a recent or ongoing infection, but can also rise after vaccination or cross‑react with other bacterial infections.
• Low or negative titres do not rule out typhoid; early infection may not yet have produced detectable antibodies.

Many factors—hydration status, recent antibiotic use, vaccination, or concurrent infections—can influence antibody levels.

Who might be advised to get this test?

• Adults or children with unexplained fever lasting more than a week.
• Travelers returning from typhoid‑endemic regions.
• Patients with gastrointestinal symptoms and a history of exposure.

Summary

The Widal test measures antibodies against Salmonella Typhi/Paratyphi. It is a supportive tool for diagnosing typhoid fever, used alongside clinical assessment and other investigations.

No fasting is required for the Widal test. If you are also scheduled for a fasting test (e.g., fasting blood glucose), follow the fasting instructions for that test.

Procedure: A healthcare professional will draw a small amount of blood (usually 5–10 mL) from a vein in your arm using a needle. The process takes about 5 minutes. You may feel a brief pinch or sting when the needle is inserted.

Precautions: No special precautions are needed. Avoid strenuous exercise or alcohol 24 hours before any blood test if you are also undergoing other investigations that require such restrictions.

Please confirm any specific preparation details with your doctor or the laboratory. This information is for educational purposes only and is not a substitute for professional medical advice.