Diagnostic accuracy of IgM antibody detection in typhoid by a modification in Widal test.

Specific IgM antibodies were detected indirectly in sera of patients of typhoid by observing fourfold or more fall in the agglutinin titres after treatment of the serum with 2-mercaptoethanol (2-ME) for removal of IgM antibodies. Significant fall in titres was observed in 94 per cent patients of bacteriologically confirmed typhoid and 67 per cent patients in whom a diagnosis of typhoid was based only on a significant Widal test result. Patients of non-typhoid febrile illnesses showed either no fall or an insignificant fall in their titres. The detection of specific IgM antibodies by this simple modification of Widal test thus seems to enhance the sensitivity and specificity of the test.