Latent tuberculosis infection: Difference between revisions
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= Definition = |
== Definition == |
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* Prior exposure to TB |
* Prior exposure to TB |
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* Goal is to identify those who are at increased risk of developing active TB and would benefit from treatment |
* Goal is to identify those who are at increased risk of developing active TB and would benefit from treatment |
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= Investigations = |
== Investigations == |
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* Tuberculin skin test (TBST) |
* Tuberculin skin test (TBST) |
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** Preferred for those who have received BCG after infancy |
** Preferred for those who have received BCG after infancy |
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= Positive TBST = |
== Positive TBST == |
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# Is it truly positive? |
# Is it truly positive? |
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#* baseline liver enzymes and vision testing |
#* baseline liver enzymes and vision testing |
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= Further Reading = |
== Further Reading == |
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* [http://blogs.jwatch.org/hiv-id-observations/index.php/common-curbsides-the-tuberculin-skin-test-and-igra-that-dont-agree/2014/11/10/ TBST vs. IGRA for latent TB] |
* [http://blogs.jwatch.org/hiv-id-observations/index.php/common-curbsides-the-tuberculin-skin-test-and-igra-that-dont-agree/2014/11/10/ TBST vs. IGRA for latent TB] |
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= Tools = |
== Tools == |
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* [http://www.tstin3d.com/en/calc.html TST in 3D online TBST/IGRA Interpreter] |
* [http://www.tstin3d.com/en/calc.html TST in 3D online TBST/IGRA Interpreter] |
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Revision as of 15:23, 17 August 2019
Definition
- Prior exposure to TB
- Goal is to identify those who are at increased risk of developing active TB and would benefit from treatment
Investigations
- Tuberculin skin test (TBST)
- Sens 90%, Spec >95
- Interferon-gamma release assay (IGRA)
- Sn 95%, Sp >95%
- Preferred for those who have received BCG after infancy
Positive TBST
- Is it truly positive?
- Consider IGRA
- BCG vaccine can be considered a cause of false positive when
- vaccine given after 12 months of age, and
- patient has no risk factors, and
- either Canadian-born non-Aboriginal, or not from endemic country
- Rule out active TB
- signs/symptoms
- CXR or CT chest
- Sputum x3 if coughing or cavitary lesions
- Evaluate risk of reactivation treatment
- INH 300 daily x9 mo with pyridoxine
- baseline liver enzymes and vision testing
Further Reading
Tools
References
- a b c Tasnim Hasan, Eric Au, Sharon Chen, Allison Tong, Germaine Wong. Screening and prevention for latent tuberculosis in immunosuppressed patients at risk for tuberculosis: a systematic review of clinical practice guidelines. BMJ Open. 2018;8(9):e022445. doi:10.1136/bmjopen-2018-022445.
