The Widal test, introduced by F. Widal in 1896, is a blood test that measures antibody titres to diagnose suspected cases of typhoid or paratyphoid fever, collectively known as enteric fever. Through the measurement of certain antibodies in the blood in reaction to antigens (foreign substances), antibody titres provide insight into the immune system's response to the body. The test detects antibodies against the O and H antigens of Salmonella Typhi and the H antigens of Salmonella Paratyphi . It uses a suspension containing killed Salmonella Typhi bacteria as the antigen to identify typhoid fever in febrile patients. Hence, those exhibiting enteric fever symptoms may find the Widal test beneficial.

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

Consider the following factors, before booking the Widal test in Hyderabad:

Prerequisites

You do not need to fast before a Widal test.

Best Time to Get Tested

The Widal test can be conducted at any time during the day.

Who Should Get a Widal Test

Anyone with symptoms like gastrointestinal issues (diarrhoea, abdominal pain, or constipation), fever, fatigue, and headache, particularly if they have been in regions with a substantial risk of typhoid or paratyphoid fever, should get a Widal test.

Cautions Before Taking the Widal Test

No special precautions are needed for this test.

The incubation period for typhoid bacteria is typically 6 to 14 days, but it can be as long as 30 days. This period marks the time between infection and the onset of symptoms. The incubation time for paratyphoid bacteria might last anywhere from 1 to 10 days. Usually, symptoms get worse over the course of 3 to 4 days.

If you show symptoms of typhoid fever, a doctor might order a Widal test. Paratyphoid fever has similar but milder, symptoms. These signs and symptoms include:

• High fever or chills

• Sore throat and persistent cough

• Headache

• Extreme fatigue

• Pain in the abdomen

• Feeling unwell, weak, or sick

• Decreased heart rate

• Loss of appetite

• Constipation

• Diarrhoea

• Sweating

• Blood in the stool

• Bleeding from the nose

• Weight loss

• Red rash on the chest and abdomen

• Confusion or hallucinations

• Difficulty in concentrating

• Poisoning of blood

• Enlarged spleen or liver

Please note: Vaccination against typhoid does not guarantee full immunity, as 20–50% of vaccinated individuals may still get the disease upon exposure.

Individuals at higher risk for typhoid might be advised to take a Widal test. These include:

• Travellers to areas where typhoid and paratyphoid are prevalent, including India, Bangladesh, the Middle East, and Africa.

• Those in close contact with an infected person.

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

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

Interpretation

Titres lower than 1:80 are considered negative, suggesting the absence of infection.

Titres of 1:80 or above are typically seen as positive, but this cutoff may vary among different populations and regions. An increasing titre, observed from multiple samples taken 4 to 6 days apart after the disease begins, is more meaningful than a single elevated titre. The test results should be assessed alongside the patient's clinical findings to determine a diagnosis.

Limitations

Vaccinated patients may show elevated antibody titres, leading to possible false-positive results. Likewise, individuals with prior infections or vaccinations might also have misleading results.

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

Although the serological results of this test are valuable, they should not replace culture-based methods for identifying the causative organisms. It is important to recover and identify the pathogens through culture and biochemical tests.