The Widal test is a blood test used to measure antibody titres when an individual is suspected to have typhoid or paratyphoid fever (collectively known as enteric fever). Antibody titres measure the presence and amount of these specific antibodies in the blood, which in turn reflects the body's immune response when it is exposed to antigens (foreign substances). The Widal test specifically detects antibodies against the O and H antigens of Salmonella Typhi and H antigens of Salmonella Paratyphi . Introduced by F. Widal in 1896, this blood test uses a suspension medium containing killed Salmonella Typhi bacterium as the antigen to identify the presence of typhoid fever in patients presenting with fever. Therefore, anyone exhibiting symptoms and indications of enteric fever may benefit from 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 Bangalore and are experiencing symptoms of enteric fever, consider getting a Widal test in Bangalore today.

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

Prerequisites

Fasting is not necessary for the Widal test.

Best Time to Get Tested

The Widal Test can be scheduled at any time during the day.

Who Should Get a Widal Test

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

Cautions Before Taking the Widal Test

There are no special precautions for this test.

The Typhoid bacteria typically have an incubation period of 6 to 14 days, although it can be as long as 30 days. The incubation period is the interval of time between the infection with the bacteria and the onset of symptoms. For the paratyphoid bacteria, it might be anything from 1 to 10 days. Most of the time, symptoms gradually worsen over the course of 3 to 4 days.

A doctor might request a Widal test if you have symptoms of typhoid fever. Similar, but less severe symptoms are also seen with paratyphoid fever. 6 These signs and symptoms include:

• High fever or chills

• Headache

• Extreme fatigue

• Feeling unwell, weak or sick

• Pain in the abdomen

• Constipation

• Diarrhoea

• Sweating

• Blood in the stool

• Sore throat and persistent cough

• Bleeding from the nose

• Weight loss

• Decreased heart rate

• Loss of appetite

• Red rash on the chest and abdomen

• Confusion or hallucinations

• Difficulty in concentrating

• Poisoning of blood

• Enlarged spleen or liver

Even those vaccinated against typhoid are not entirely immune, as 20–50% of vaccinated individuals may still contract the disease upon exposure.

Individuals with an increased risk of typhoid may also be recommended a Widal test. These include:

• People who are in close proximity to an infected individual.

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

• Travellers to regions where typhoid and paratyphoid are prevalent (such as India, Bangladesh, Middle Eastern countries, and African countries.)

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

Interpretation

A titre less than 1:80 is considered negative, indicating the patient does not have an infection.

Titres of 1:80 or higher are typically considered positive, although this threshold may vary among different populations and regions. A rising titre, observed through two or more samples taken at 4- to 6-day intervals after the onset of the disease, is considered more significant than a single high titre. The results of the test should be correlated with the patient’s medical findings to reach a final diagnosis.

Limitations

Patients vaccinated against typhoid may display elevated antibody titres, potentially leading to false-positive results. Similarly, the results may be misleading in individuals with prior infections or immunisations.

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

Although the serological findings of this test are valuable, they should not replace culture-based methods for identifying the causative organisms. Efforts should be made to recover and identify the pathogens through culture and biochemical tests.