WIDAL PROFILE

Widal Profile (Widal Test)

The Widal test is a blood test used to help diagnose typhoid fever, an infection caused by the bacterium Salmonella enterica (especially serovar Typhi).

It detects antibodies in a patient’s blood against specific antigens of the bacteria.

🧪 What Does the Widal Test Measure?

The test looks for antibodies against:

1. O antigen (Somatic antigen)

   • Indicates active or recent infection

   • Appears early in the disease

2. H antigen (Flagellar antigen)

   • Appears later

   • Persists longer in the blood

Some labs also test for:

• AH and BH antigens (related to paratyphoid strains)

📊 Understanding Widal Results

Results are reported as titers (e.g., 1:40, 1:80, 1:160, 1:320).

• A higher titer means more antibodies are present.

• In many areas, a titer of ≥1:160 may suggest infection.

• A fourfold rise in titer over 7–10 days is more reliable for diagnosis.

⚠️ Important: Normal cutoff values vary by region.

⏱ When Is It Positive?

• Usually becomes positive after 5–7 days of fever

• Early testing may give false-negative results

⚠️ Limitations of Widal Test

The Widal test is not highly specific or sensitive.

It may give:

• False positives (due to previous infection, vaccination, or other infections)

• False negatives (early infection or prior antibiotics)

Because of this, more reliable tests like:

• Blood culture (gold standard)

• Typhoid IgM rapid tests
  are often preferred.

🩺 Symptoms of Typhoid Fever

• Prolonged high fever

• Headache

• Weakness

• Abdominal pain

• Constipation or diarrhea

• Loss of appetite