ABSTRACT
OBJECTIVES: To evaluate the diagnostic specificity of modified Widal for recent infection in comparison with conventional Widal test. METHOD: Modified widal test was simultaneously done along with conventional Widal test in serum samples obtained from 50 bacteriologically positive cases of Salmonella typhi infection as well as 50 healthy individuals. RESULTS: A four-fold difference in the titres was noticed in the 50 sera of the test group and no charge in the titres of the control group. The early rising O antibodies which are predominantly IgM in nature. These are due to recent infection and are inactivated by 2-mercaptoethanol. On the other hand H is a mixture of IgG and IgM hence IgM portion gets inactivated giving rise to fall in titre. By inactivating IgM antibodies in modified Widal test, the agglutination would be brought about only by specific IgG while in the conventional Widal test agglutination is due to specific IgG and IgM. The difference in the titres indicates specific IgM class of antibodies which is the hallmark of recent infection. CONCLUSION: If conventional Widal test and modified Widal test are simultaneously done, one can be definite about the diagnosis of enteric fever.
Subject(s)
Antibodies, Bacterial/isolation & purification , Case-Control Studies , Diagnostic Techniques and Procedures , Humans , Mercaptoethanol/diagnosis , Typhoid Fever/bloodABSTRACT
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.