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WIDAL TEST (SLIDE METHOD)

About the test
What is this test done for?
Widal test is a specific blood test, which detects the presence of serum agglutinins (H and O) in the patient’s serum to detect presence of typhoid infection.
Why is it Done?
Widal test involves detecting bacteria that cause typhoid fever in the blood by identifying certain antibodies taken from an infected person. It is an assumptive blood test for enteric (typhoid) fevers.
When should it be performed?

The test should be performed when someone has the following signs and symptoms:

  • High fever which is continuous, persistent,
  • Headaches
  • Joint pain
  • Body pain
  • Poor appetite
  • Diarrhea, nausea, vomiting
  • Lethargy and feeling fatigue
  • Abdominal pain
How is it done
A blood sample will be collected from a vein in your arm. No fasting is required for this test.
Results
The results are interpreted on the basis of agglutination. If agglutination is seen within a minute, it indicates active typhoid infection. If there is no agglutination, it indicates no infection. However, there have been false positive reports seen in patients who have undergone antibiotic treatments, vaccinated for Salmonella, or with a past history of typhoid fever. Therefore, a second test in the subsequent week may be needed to differentiate between past and present infection.
Other Tests
CBC is very important as it helps confirm the diagnosis. Furthermore, to rule out other fevers, tests like Dengue IgG and Liver function tests should be performed. A stool culture might be needed to confirm a typhoid infection.