What It Is
The Widal test is a blood test used to help detect typhoid fever, a bacterial infection caused by a specific type of Salmonella bacteria.
What It Checks
The Widal test measures the level of certain antibodies in the blood that the body produces in response to the bacteria responsible for typhoid fever. A rise in these antibody levels can suggest a current or recent infection.
Why It's Used
The Widal test is commonly used, particularly in regions where typhoid fever is more common, to help support a diagnosis of typhoid in people presenting with symptoms consistent with the illness, such as prolonged fever.
How It's Done
The Widal test requires a standard blood sample, typically drawn from a vein in the arm. In the laboratory, the sample is tested against specific bacterial components to measure the level of antibodies present, often with the test repeated after a period of time to look for a rise in antibody levels, which provides more meaningful information than a single reading alone.
Background
The Widal test is named after a French physician who developed the technique in the late 19th century, building on early research into how the body's immune system responds to specific bacterial infections. It became a widely used diagnostic test for typhoid fever through much of the 20th century, particularly in regions where more specific laboratory testing, such as bacterial culture, wasn't as readily available, and it remains in use today, often alongside other diagnostic approaches.