The Widal test in a normal healthy population in the Sudan.
The Widal test was performed in 114 normal individuals from the Gezira area in Sudan. Salmonella typhi O agglutinins were found at a titre of 1.320 in 12 (10.5%) of them. Salmonella paratyphi A agglutinins were found at 1.160 in 5 (4.3%) and Salmonella paratyphi B "O" agglutinins were found in 6 (5.3%) at a titre of 1.160. None of these individuals had a history of typhoid fever or vaccination with TAB vaccine. The following points emerged: (i) normal healthy people in the Sudan have high antibody titres of Salmonella typhi; (ii) the Widal test in the Sudan should be interpreted against this background; (iii) previous diagnostic titre of 1.160 for S. typhi results in high false positive results; (iv) a titre above 1.320 is suggested as diagnostic for S. typhi; 1.160 for both S. partyphi B and S. paratyphi A.
Department of Microbiology, College of Medicine, Sultan Qaboos University, Al-Khod, Muscat, Sultanate of Oman.
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D000372:Agglutination Tests / Q000592:standards*; D005069:Evaluation Studies as Topic; D006801:Humans; D008403:Mass Screening / Q000379:methods / Q000592:standards; D010284:Paratyphoid Fever / Q000097:blood* / Q000453:epidemiology / Q000276:immunology; D012016:Reference Values; D012482:Salmonella paratyphi A; D012484:Salmonella paratyphi B; D012680:Sensitivity and Specificity; D016036:Seroepidemiologic Studies; D013397:Sudan / Q000453:epidemiology; D014435:Typhoid Fever / Q000097:blood* / Q000453:epidemiology / Q000276:immunology