How you do widal test?

Widal test is done by qualitative method or quantitative method.

Quantitative method:-Take a set of 8dry clean test tubes.

Place 1.9ml saline in tube no.1 and 1ml saline in rest of tubes. Add 0.1ml serum in 1st tube mix well it is dilution of 1:20

Transfer 1ml diluted serum from tube no.1 to tube no. 2 and so on.

Through tube no.7 discard 1ml of fluid after mixing.

leave 1ml saline in tube no.8.

Add one drop of appropriate antigen(use only that antigen suspension which has given a positive reaction in screening test.

Mix well and incubate overnight at 37.c

Examine for agglutination.

Interpretation:- Only a titre above 1:80 should be considered as significant

A rising titre (done each week)is considered to be definite evidence of infection.