Value of single Widal test in the diagnosis of typhoid fever

The usefulness of single Widal test in the diagnosis of typhoid fever was investigated. The test was done on 50 normal children, 50 children with non typhoidal fevers and 30 culture proved typhoid cases. Twenty one (70%) and nine (30%) of thirty typhoid fever cases had 'O' and 'H' agglutinin titer levels of more than or equal to 1:160, respectively as compared to only 3 (3%) and to 1 (1%) among controls. These differences were significant (p < 0.001). Twenty two (73.3%) out of thirty typhoid fever cases had either an 'O' or 'H' agglutinin titer of more than or equal to 1:160 as compared to only 3 (3%) among controls. An 'O' agglutinin titer of 1:160 had a specificity of 97%, a sensitivity of 70% and an accuracy of 90%. An 'H' agglutinin in titer of 1:160 was had a specificity of 97%, a sensitivity of 30% and an accuracy of 83.1%. Based on the above analysis, 'O' or 'H' titers of 1:160 or more were indicative of typhoid fever. Similarly, when the 2 titers were considered together, either 'O' or 'H' titers of 1:160 or more were suggestive.