Widal test and its medical significance in diagnosis

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Febrile condition is a common disease caused by different pathogens. The most common microorganism that causes it is Salmonella typhi and Salmonella parartyphi. The single Widal agglutination test rather than blood culture or other cultures is commonly
used in diagnose typhoid fever.

This study evaluate the medical significance and value of a single Widal test result in diagnosis febrile typhoid fever patients. It is a retrospective study on febrile patients to diagnose typhoid fever and 100 patients were enrolled in the study. Blood sample was collected from the patients and tested for qualitative Widal slide agglutination test for confirmation of the disease. This test is used for detecting the presence of anti Salmonella typhi O and H antibodies, anti Salmonella paratyphi A (O and H) antibodies, anti Salmonella paratyphi B (O and H) antibodies in the patients’ serum. Antibodies against S typhi O antigen were 72/100 (72%), and to H antigens were 64/100 (64%). Regarding S paratyphi A, the reactive O antigen was 34/100 (34%) and Hantigen was 16/100 (16%) while S paratyphi Oantigen was 23/100 (23%) and H was 14/100(14%).

Among those patients who had positive agglutination reaction for S typhi results, 22(30.55%) had titer of 1:360 for Oantigen and 37 (57.81%) had titer of 1:40 of H antigen of Styphi. Thus, Single Widal agglutination test is used as diagnosis of Typhoid fever by interpretation of both O and H antigen and the cut-off titer in Iraq was 160 because it’s endemic in this area.