The Widal test procedure helps identify typhoid fever caused by Salmonella enterica serotype Typhi. Developed by Georges Fernand Isidore Widal in the late 19th century, provided insights into antibodies indicative of exposure to the typhoid-causing bacterium.
WIDAL Test: Definition, Principle, Procedure and Results The Widal test, also referred to as the Widal agglutination test, is a serological test used for a presumptive diagnosis of typhoid fever and paratyphoid fever, which are caused by certain bacteria named Salmonella.
The Widal Test is a simple and commonly used blood test to help detect typhoid infection. The procedure is quick, safe and usually completed within a short time.
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.
Widal test is a common agglutination test employed in the serological diagnosis of enteric fever. This test was developed by Georges Ferdinand Widal in 1896 and helps to detect presence of salmonella antibodies in a patient’s serum.
It is performed in the following steps: Place a drop of sample serum in each reaction circle of the Widal test card labeled as O, H, AH, and BH. Observe for macroscopic agglutination within a minute. This test is performed to measure the level of antigens present in the serum sample.
Widal test is an easy, cheap, easily accessible and non invasive test to perform. It is of great significance in laboratories where blood cultures facility is not available (the results must be interpreted cautiously, as negative results do not exclude typhoid fever).