The Widal test is a diagnostic blood test introduced by F. Widal in 1896 to measure antibody titres in suspected typhoid or paratyphoid fever cases, collectively termed enteric fever. Antibody titres reflect the immune response by indicating the presence and levels of specific antibodies in the blood in response to foreign substances (antigens). The Widal test targets antibodies against the O and H antigens of Salmonella Typhi and the H antigens of Salmonella Paratyphi . It uses a suspension medium with killed Salmonella Typhi bacteria as the antigen to diagnose typhoid fever in patients with fever. Therefore, individuals with symptoms of enteric fever may benefit from undergoing a Widal test.

Given its role in diagnosing enteric fever, the Widal test can be a critical diagnostic tool aiding in timely detection and treatment. Therefore, if you live in Delhi and are experiencing symptoms of enteric fever, consider getting a Widal test in Delhi today.

Before booking the Widal test in Delhi, consider the following factors:

Prerequisites

No fasting is needed for the Widal test.

Best Time to Get Tested

You can schedule the Widal test at any time during the day.

Who Should Get a Widal Test

People showing symptoms such as fatigue, fever, gastrointestinal issues (abdominal pain, diarrhoea, or constipation), and headache, especially if they have been in areas with an elevated risk of typhoid or paratyphoid fever, should undergo a Widal test.

Cautions Before Taking the Widal Test

There are no special precautions required for this test.

Typhoid bacteria have an incubation period of 6 to 14 days, and in some cases, up to 30 days. This period is the interval between infection and the appearance of symptoms. Paratyphoid bacteria have an incubation period of 1 to 10 days. Symptoms often worsen gradually over a period of 3 to 4 days.

A doctor might request a Widal test if you exhibit symptoms of typhoid fever. Paratyphoid fever shows similar, but less severe, symptoms. These signs and symptoms include:

• High fever or chills

• Headache

• Loss of appetite

• Constipation

• Red rash on the chest and abdomen

• Extreme fatigue

• Feeling unwell, weak, or sick

• Pain in the abdomen

• Diarrhoea

• Sweating

• Blood in the stool

• Sore throat and persistent cough

• Bleeding from the nose

• Weight loss

• Decreased heart rate

• Difficulty in concentrating

• Confusion or hallucinations

• Enlarged spleen or liver

• Poisoning of blood

It is important to keep in mind that typhoid vaccination does not offer complete immunity, with 20–50% of vaccinated people potentially contracting the disease upon exposure.

Individuals at higher risk for typhoid may be recommended to undergo a Widal test, including:

• Young children, as they are more susceptible to these diseases than adults.

• People who are in close contact with an infected individual.

• Travellers to regions with high rates of typhoid and paratyphoid, such as India, Bangladesh, the Middle East, and Africa.

Below is a breakdown of the results of the Widal test:

Interpretation

A titre under 1:80 is considered negative, meaning the patient likely does not have an infection.

Titres of 1:80 or more are usually deemed positive, though the exact threshold can vary by population and region. A rising titre, noted through two or more samples taken 4 to 6 days apart after symptom onset, is more indicative than a single high titre. The results should be correlated with the patient’s clinical findings to make a final diagnosis.

Limitations

Elevated antibody titres in vaccinated patients may result in false-positive outcomes. Similarly, results may be misleading for individuals with previous infections or immunisations.

Agglutinins typically appear in the blood by the end of the first week of infection, so samples taken earlier may show negative results.

While the serological findings from this test are useful, they should not substitute culture-based methods for identifying the causative organisms. Efforts should be made to recover and identify the pathogens through culture and biochemical tests.