1)prepare the blood plate(black background).
2)add one drop serum
3)add antigen (o,H,AH,BH)
4)mix the antigen and serum.
5)rotate the sample (1 min)
6)result:positive reactive
:negative non-reactive
The blood test for typhoid is called the Widal test. It detects antibodies in the blood against the Salmonella typhi bacteria, which causes typhoid fever.
In a Widal test, "H" refers to the flagella antigen of Salmonella typhi while "O" refers to the somatic antigen of the bacteria. The presence of antibodies against these antigens indicates a recent or current infection with Salmonella typhi, the bacterium that causes typhoid fever.
Serial dilution in Widal test helps to determine the titer of antibodies in the patient's serum by observing the agglutination reaction with specific antigens. By diluting the serum sample in a stepwise manner, the titer at which agglutination occurs can be determined, providing valuable information about the presence and concentration of antibodies against Salmonella typhi and Paratyphi antigens in the blood.
The biochemical test commonly used to identify Salmonella typhi is the Widal test. This test detects antibodies produced in response to a Salmonella typhi infection by measuring agglutination (clumping) reactions between the bacteria and specific antibodies in the patient's serum. Other tests like blood culture and polymerase chain reaction (PCR) can also be used for confirmation.
The procedure indicates that the amount of time the test tube was kept boiling in the water bath should be minimized. The water bath should never be allowed to boil dry.
What is false positive in widal test
The main difference between the Widal slide test antigen and the Widal tube test antigen lies in the method of reaction visualization. In the Widal slide test, the reaction is observed on a glass slide under a microscope, whereas in the Widal tube test, the reaction is seen in small test tubes. Both tests detect antibodies against specific Salmonella antigens, but differ in their setup and visual interpretation.
I mean widal test result positive after treatment
Isolated Widal test reading does not have much clinical significance. Rising titre of Widal test done one week apart, in a febrile patient, indicates typhoid fever. You can have such rising titre of Widal test in healthy patient, after dose of typhoid vaccine.
1:80 titre is significant for determination of widal positive.
widal test
To a certain extent yes.The post antibiotics Widal Test will have Low titers of agglutinins.Hence the test may be reported as False Negative.
The blood test for typhoid is called the Widal test. It detects antibodies in the blood against the Salmonella typhi bacteria, which causes typhoid fever.
manual test of widal method
widal test.
Widal test is negative in incubatory carrier. Widal test is always positive in chronic carrier.
In Widal test, you measure the antibodies. It takes minimum one week to develop the antibodies of typhoid bacteria.