Understanding Widal Test : Diagnostic Test To Diagnose Typhoid Fever

The Widal test is a widely used serological test that helps in diagnosing typhoid fever. Named after Georges Fernand Isidore Widal, a French physician who introduced it in 1896, the test detects antibodies in the blood that are produced in response to Salmonella Typhi or Salmonella Paratyphi infection.

Before Knowing Widal Test We Have To Understand Typhoid Fever

Typhoid fever is a bacterial infection caused by the Salmonella Typhi bacteria. It spreads through contaminated food, water, and poor sanitation. The disease is prevalent in regions with inadequate access to clean drinking water and sanitation facilities. Symptoms of typhoid fever include prolonged fever, abdominal pain, weakness, loss of appetite, and sometimes rash.

Why Widal Test Is Done ?

The primary purpose of the Widal test is to detect and measure the presence of specific antibodies in a patient’s blood. These antibodies are produced in response to the antigens of Salmonella Typhi and Paratyphi. The test is typically ordered when a patient presents with symptoms indicative of typhoid fever and has a history of exposure or travel to an endemic area.

How The Widal Test Is Done In Laboratory ?

The Widal test is a simple and rapid diagnostic procedure. It involves the following steps:

1.      BloodSample Collection: A blood sample is drawn from the patient.

2.      Serum Separation: The blood is processed to obtain the serum, which contains antibodies.

3.      Reaction with Antigens: The serum is mixed with known Salmonella antigens (O and H antigens).

4.      Observation: The mixture is observed for agglutination (clumping). The presence of agglutination indicates a positive reaction, suggesting a typhoid infection.

The test results are typically represented as titers, which show the highest dilution of serum that still results in visible agglutination.

How to Interpretate Widal Test Result ?

·         Positive Result: A significant rise in antibody titers (generally fourfold) is indicative of a current or recent infection.

·         Negative Result: Low or absent antibody levels suggest no active infection.

·         False Positives and Negatives: Factors such as prior vaccination, past infections, or other illnesses may influence the results. Therefore, the test should always be interpreted alongside clinical symptoms and other diagnostic findings.

What are the Advantage Of Widal Test ?

·         Simple and cost-effective

·         Quick results compared to blood cultures

·         Useful in resource-limited settings

What are The Limitation Of Widal Test ?

·         May give false-positive or false-negative results

·         Limited specificity and sensitivity

·         Cannot differentiate between current and past infections

What Are The Alternative Diagnostic Technique ?

While the Widal test remains a valuable tool in many regions, other diagnostic methods like blood culture, stool culture, and Typhidot Test more accurate results. Blood cultures are considered the gold standard for diagnosing typhoid fever, especially in the early stages of infection

Which is the Best Widal Testing Lab In Delhi ?

SCD homecare A division of Sheetal Chhaya Diagnostics is a leading diagnostic center Providing The widal test at Rs 200 . They offer home collection of Blood samples in Delhi and Gurugam