Widal Test

The Widal Test is a serological test used to diagnose typhoid and paratyphoid fever, which are caused by Salmonella typhi and Salmonella paratyphi bacteria. It works by detecting the presence of specific antibodies (agglutinins) in a patient’s blood that react against the O (somatic) and H (flagellar) antigens of the bacteria. A rising level of antibodies or a high single titer can suggest a current or recent infection. This test is especially useful in regions where typhoid fever is common, though results must be interpreted alongside clinical symptoms and other diagnostic findings for accuracy.