the meaning of a positive serology Widal test
What Does a Positive Serology Widal Test Mean
The Widal test is a serological test that is used to detect antibodies to Salmonella typhi, the bacterium that causes typhoid fever. The test is performed by mixing a patient’s serum with antigens from S. typhi. If the patient has antibodies to S. typhi, the antigens and antibodies will clump together, or agglutinate.
A positive Widal test result indicates that the patient has been exposed to S. typhi. However, it is important to note that a positive Widal test result is not always specific for typhoid fever. Other diseases, such as paratyphoid fever, can also cause a positive Widal test result.
The specificity of the Widal test can be improved by taking two blood samples from the patient, one during the acute phase of illness and one during the convalescent phase. If the titer (the concentration of antibodies in the serum) of antibodies to S. typhi increases from the acute phase to the convalescent phase, this is more likely to be a sign of typhoid fever.
The Widal test is not the only test that can be used to diagnose typhoid fever. Other tests that may be used include
* Blood culture This test is the most sensitive test for typhoid fever. It involves growing S. typhi bacteria from a blood sample.
* Bone marrow culture This test is more sensitive than blood culture, but it is also more invasive.
* Urine culture This test can be used to detect S. typhi in the urine.
* Stool culture This test can be used to detect S. typhi in the stool.
If you have a positive Widal test result, your doctor will likely order further tests to confirm the diagnosis of typhoid fever. Treatment for typhoid fever typically involves antibiotics.
Here are some additional things to keep in mind about the Widal test
* The Widal test is not always accurate. False-positive results can occur, especially in people who have been vaccinated against typhoid fever.
* The Widal test can take several days to complete.
* The Widal test is not available in all countries.
If you have any questions about the Widal test, talk to your doctor.