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WIDAL TEST (TUBE METHOD)

About the test
What is this test done for?
The test measures the presence of antibodies to the O & H antigen of salmonella typhi bacteria in the patient’s serum.
Why is it Done?
It is done to confirm the diagnosis of enteric fever i.e. typhoid.
When should it be performed?

It is performed when patient presents with high fever 104 °F for a week, continuously along with any of the following symptoms:

  • Poor appetite
  • Headache
  • Generalised aches and pains
  • Lethargy, weakness
  • Abdominal pain and discomfort, diarrhoea
  • Skin rash
How is it done
A blood sample will be collected from a vein in your arm. Fasting is not required prior to sample collection. This test is done in a laboratory in 4 sets of 8 test tubes each and hence, the test is called Widal test by tube method.
Results
  • Results can be positive or negative. Negative test implies absence of infection).
  • Positive  test, is seen usually in the second week after infection.
  • If the TO antigen titre is above 1: 160, it means an active infection.
  • If the TH antigen titre is above 1:160, it means it is an old infection or the person has been immunized using typhoid vaccine.
  • Previous typhoid vaccination may contribute to false positive results.
  • False positive reaction may be inferred owing to: other infections of non-enteric salmonella such as typhus, immunological disorders, chronic liver disease, presence of malaria parasites.
Other Tests
Blood culture, stool culture, urine culture, Typhidot test should be done to confirm the diagnosis.
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