Question

47) The Widal test is used for the detection of Salmonella typhi and other subspecies.
This test is based on the principle where?
a) the antigens are detected using the neutralization assay
b) the antigen combines with its soluble antibody and form a lattice and develops a
visible precipitate
c) the antigens bind to RBCs and form the agglutination
d) None of the above​

Answer 1

Answer:

c) the antigens bind to RBCs and form the agglutination

Answer 2

The Widal test is positive if TO antigen titer is more than 1:160 in an active infection, or if TH antigen titer is more than 1:160 in past infection or in immunized persons. A single Widal test is of little clinical relevance especially in endemic areas such as Indian subcontinent, Africa and South-east Asia.