Page 136 - MNUmicrobiology practical 2025
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General Microbiology & Immunology (PM 401) second level Semester 4 2024/2025
3. The Widal test interpretations:
Interpretations of the
The titer of the antibody
Widal test
O-antigen = >1:160 Active infection
Past infection or
H-antigen = >1:160
immunized
Rising titer = 1:40 to 1:80
Diagnostic
to 1:160
O-antigen
o Antigen-O will be positive in the acute stage, and the titer will be more than
1:160.
o O-antigen appears early and also disappears early.
H-antigen
o H antigen rises late and disappears late.
o It is positive in the recovery stage.
General Microbiology & Immunology (PM 401) Practical note Page 125
