What is the interpretation of Widal test?
What is the interpretation of Widal test?
The Widal test is positive if “O” antigen titer is >1:160 = active infection. If the “H” antigen titer is >1:160, it indicates past infection or in immunized persons.
How do you read a Widal test slide?
Add one drop each of ‘O’, ‘H’, ‘AH’ and ‘BH’ antigens to the remaining four reaction circles. Mix contents of each circle uniformly over the entire circle with separate mixing sticks. Rock the slide, gently back and forth and observe for agglutination macroscopically within one minute.
What is Widal test slide share?
The tests measure agglutinating antibodies directed against a Salmonella O somatic surface antigen and/or a Salmonella H flagella antigen of the suspected organism. • The Widal test detects antibodies against O and H antigens.
What does Widal test positive means?
The Widal test is positive if TO antigen titer is more than 1:160 in an active infection, or if TH antigen titer is more than 1:160 in past infection or in immunized persons. A single Widal test is of little clinical relevance especially in endemic areas such as Indian subcontinent, Africa and South-east Asia.
What is the normal Widal test result?
Conclusion: In case of singular Widal test, baseline values for the normal range was found to be 1:20 – 1:80 for all the antigens (TO, TH, AO, AH, BO, BH), except BH, for which it was 1:20-1:40.
What is the normal value of Widal test?
What is Widal test positive?
What is the normal range of Widal test?
What is Widal test negative?
So a negative Widal test result has a good predictive value for the absence of the disease but a positive result would have a low predictive value for the presence of typhoid fever [9].
What is Widal test normal value?
How do you use Widal test on a slide?
Place one drop of positive control on one reaction circles of the slide. Pipette one drop of Isotonic saline on the next reaction cirlcle. (-ve Control). Pipette one drop of the patient serum tobe tested onto the remaining four reaction circles. Add one drop of Widal TEST antigen suspension ‘H’ to the first two reaction circles. (PC & NC).
What is the principle of Widal test?
The main principle of widal test is that if homologous antibody is present in patients serum, it will react with respective antigen in the reagent and gives visible clumping on the test card and agglutination in the tube.
What does no agglutination mean on a Widal test?
No agglutination is a negative test result and indicates absence of clinically significant levels of the corresponding antibody in the patient serum. The titre of the patient serum using Widal test antigen suspensions is the highest dilution of the serum sample that gives a visible agglutination.
What is the significance of Widal test antigen suspensions?
The titre of the patient serum using Widal test antigen suspensions is the highest dilution of the serum sample that gives a visible agglutination. The sample which shows the titre of 1:100 or more for O agglutinations and 1:200 or more for H agglutination should be considered as clinically significant (active infection).
