Editing Mantoux test (section)

==False negative result==
Reaction to the PPD or tuberculin test is suppressed by the following conditions:
* Recent TB infection (less than 8–10 weeks)
* [[Infectious mononucleosis]]
* Live virus vaccine – The test should not be carried out within 3 weeks of live virus vaccination (e. g. [[MMR vaccine]] or [[Sabin vaccine]]).
* [[Sarcoidosis]]
* [[Hodgkin's disease]]
* [[Corticosteroid]] therapy/[[steroid]] use
* [[Malnutrition]]
* [[Immunodeficiency|Immunological compromise]] – Those on immuno-suppressive treatment or those with [[HIV]] and low CD4 [[T cell]] counts, frequently show negative results from the PPD test.{{Citation needed|date=December 2009}}
This is because the immune system needs to be functional to mount a response to the protein derivative injected under the skin. A false negative result may occur in a person who has been recently infected with TB, but whose immune system hasn't yet reacted to the bacteria.
* [[Common cold|Upper respiratory virus infection]]
In case a second tuberculin test is necessary it should be carried out in the other arm to avoid hypersensitising the skin.