WIDAL test

This is a serological test for typhoid and paratyphoid fever
Set up 2 rows of 6 tubes each
make dilutions of 1/40 up to 1/1280
Add the O antigen and H antigen to separate rows
O antigen is blue, and O agglutination is granuler
Vigorous shaking of the tube when reading will not destroy the agglutination
H antigen is pink, and H agglutination is floccular (cloud like)
Vigorous shaking will destroy the agglutination which is rectified by light centrifugation
O are incubated at 37 degrees
H are incubated at 56 degrees

This test is done when MC and S is negative. Patients dont visit the Dr at the appropriate time.
The organism is shed in the blood in weeks 1-2, in urine in weeks 2-3, and in stool indefinitely.
The name of the serotying is the Kauffman White scheme. The types of antigens tested for are the O and H. The Vi antigen is tested for to determine if the patient is a carrier