WIDAL Test

The Widal test is a blood test that can help diagnose typhoid fever, also known as enteric fever:

How it works

A patient's serum is mixed with antigens from the bacteria that causes typhoid fever, and then tested for antibodies against those antigens. If antibodies are present, the test is positive.

History

The Widal test was developed in 1896 by Georges-Fernand Widal.

Usage

The Widal test is still used in many developing countries, but is not commonly performed in the United States and other developed countries.

Limitations

The Widal test can produce false positives or false negatives for a number of reasons, including:

Vaccination against typhoid fever

Infections with other bacteria

Performing the test too early in the disease course

Procedure

The Widal test involves drawing a blood sample from a vein in the arm, and then transferring the sample to a lab for processing