An evaluation of modified Widal test in the diagnosis of enteric fever.

Serum samples obtained from 50 bacteriologically positive cases of Salmonella Typhi infection as well as 50 healthy individuals were subjected to conventional and modified Widal tests simultaneously. A 4-fold difference in the titres was noticed in 50 sera of the test group and no change in the titres of the control group. The early rising 'O' antibodies which are of IgM in nature and formed due to recent infection are inactivated by 2-mercaptoethanol while it has no effect on IgG antibodies which are formed due to flagellar 'H' antigens or due to anamnestic response or by nonspecific reasons. The use of modified Widal test along with conventional one can therefore help in the diagnosis of enteric fever with certainty.