Widal Test for Typhoid

The Widal test is a qualitative serological agglutination test that detects the presence and measures the titer of antibodies in blood serum against the flagellar (H) and somatic (O) antigens of Salmonella bacteria causing typhoid fever (Salmonella Typhi) and paratyphoid fever (Salmonella Paratyphi). The reaction shows an immune response indicating past exposure or current infection.