Salmonella typhi and Salmonella paratyphi A, B and C are bacteria that cause a potentially severe and occasionally life-threatening illness known as enteric fever (typhoid and paratyphoid) in humans. Recognition of the disease is important to diagnose and treat them early, to avoid potentially fatal complications.

The Biorex Diagnostics Febrile Antigen (Widal) test is a common agglutination test employed in the serological diagnosis of enteric fever and helps to detect the presence of Salmonella antigens in a patient’s serum. Patients infected with Salmonella produce antibodies against the antigens of the organism. Antibodies in serum produced in response to exposure to Salmonella organisms will agglutinate bacterial suspension which carries homologous antigens.