Tuberculin Skin Testing Resource

Tuberculin Skin Testing Resource
DURHAM REGION HEALTH DEPARTMENT
Fax: 905-666-6215
Phone: 905-668-7711 or 1-800-841-2729
Monthly Reporting..................................................................ext. 2996
Immediate Reporting..............................................................ext. 2996
Disease Outbreaks/Rabies Exposure............................905-723-3818
Environmental Help Line.................905-723-3818 or 1-888-777-9613
Durham Health Connection Line.....905-666-6241 or 1-800-841-2729
durham.ca/TB
If you require this information in an accessible format, contact 1-800-841-2729.
2014
The Tuberculin Skin Test (TST) is a useful tool for diagnosing latent tuberculosis infection
(LTBI). It should not be used in diagnosing active TB. Testing for LTBI is indicated when the risk
of developing active TB is increased.
There are four general situations when the risk of active TB disease is increased:
 Contact of a person with a recent diagnosis of active, contagious respiratory TB
 Immigrants and visitors from countries of high TB incidence within 2 years of arrival to
Canada
 Increased risk of reactivation of TB due to impaired immunity
(e.g. HIV, diabetes, renal failure, immunosuppressant
medication)
Think
 When there is radiographic evidence of old, healed TB but
TB!
no prior treatment or inadequate treatment
1-800-841-2729
durham.ca
The TST consists of the injection of a small amount of purified
protein derived from mycobacterium tuberculosis bacteria.
Persons who have a cell-mediated immunity to this bacteria will
develop a delayed hypersensitive reaction within 48-72 hours
causing localized swelling and an induration of the skin at the
injection site.
INTRODUCTION
When to AVOID TST:
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A previous severe reaction
Known active TB or known TB treatment in the past
Extensive burns or eczema at test site
Documented previous positive reaction
When to DEFER TST:
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Persons with viral infections (eg. Mumps, influenza). Defer for 4 weeks.
Recent immunization with live virus vaccine (MMR or varicella). Defer for 4 weeks.
When NOT to defer TST:
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People who have been immunized with a non-live-virus vaccine (eg. tetanus, pertussis)
Pregnant or breastfeeding women
Anyone with a previous Bacille Calmette-Guerin (BCG) vaccination
Those taking low dose corticosteroids daily (e.g. a dose of <15mg prednisone daily for
2-4 weeks which may suppress tuberculin reactivity)
Anyone with a history of a non-severe reaction (without blistering, ulceration or necrosis
at the site) but the reaction was not documented in millimeters
Anyone with a common cold
TO AVOID, DEFER OR NOT DEFER
2-step TST
Assists in establishing a true baseline result for people who will have future or serial testing.
 Should be performed on individuals who will be having TST’s done at regular intervals (e.g. health
care professionals, corrections staff, shelter staff)
A 2-step TST needs to be performed only ONCE if properly performed and documented. A 2-step
never needs to be repeated.
 Any future TST should be one step, regardless of how long it has been since the last TST.
 If the first test is negative, a second test is given 1-4 weeks later to complete the 2-step TST.

Person with Documented Results of Previous 2-Step TST
If both tests were negative
If any previous test was
positive
Done > 12 months ago
Done < 12 months ago
A 1-step TST is necessary
No further testing is required
Refer to *Reporting
Note: If the result of this TST is positive,
Refer to *Reporting
Person with Undocumented TST
A 2-step TST is required
If both tests are negative
If first test is positive
No further testing is required
Do not complete second step
Refer to *Reporting
PERSON WITH UNDOCUMENTED / DOCUMENTED TST
Ensure that the client can return within 48-72 hours to have the TST read
Place the forearm palm side up

Use the inner aspect of the forearm. Select intact skin area preferably about 4 inches
(10cm) below the elbow that is free of tattoos, scars, and superficial blood vessels

With the bevel of the needle upward, insert the needle with the point of the needle into
the superficial layers of the skin at a 5 to 15 degree angle

A definite white bleb or “wheal” about 6-10 mm in diameter should appear and then
disappear in 10-15 minutes
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If a drop of blood is present at the injection site, dab it with a cotton ball and do not
cover it with a bandage
PLANTING
Mark the edges of induration across the forearm with a pen held at a 45 degree
angle
Using the TST ruler, measure the distance between the pen marks and record the
induration in millimeters NOT just positive or negative (if you require a TST ruler call
the health department )
Measure induration – NOT erythema (redness)
Record the date, and the size in mm of the “wheal” on the patient's immunization
record or health record
Record horizontal measurement only
READING
In general a TST result of 0-4 mm is considered negative, and no treatment or medical
follow up is indicated.
TST Result
0-4 mm
Situation in which reaction is considered positive
Child under 5 years of age and high risk of TB infection
HIV infection
Contact with infectious TB case within the past 2 years
Presence of fibronodular disease on chest x-ray (healed TB, and not
previously treated)
> 5 mm
Organ transplantation (related to immune suppressant therapy)
TNF alpha inhibitors
Other immunosuppressive drugs, e.g. corticosteroids (equivalent of ≥15
mg/day of prednisone for 1 month or more; risk of TB disease increases
with higher dose and longer duration)
End-stage renal disease
> 10 mm
All others, including the following specific situations:
• TST conversion (within 2 years)
• Diabetes, malnutrition (<90% ideal body weight), cigarette smoking,
daily alcohol consumption (>3 drinks/day)
• Silicosis
• Hematologic malignancies (leukemia, lymphoma) and certain
carcinomas (e.g. head and neck)
Canadian Tuberculosis Standards 7th Edition 2013
Note: Person with medical conditions that severely weaken the immune system may have a negative TST even
though they have TB infection. Further assessment by a specialist with expertise in tuberculosis is
recommended (e.g. Infectious Disease, Respirologist, TB Clinic)
The online TST/IGRA interpreter (Version 3.0) is available at www.tstin3d.com to assist in TST and IGRA
interpretation.
INTERPRETATION
Report positive TSTs to the Durham Region Health Department
Tel: 905-668-7711 ext. 2996 or 1-800-841-2729 ext. 2996
Confidential Fax: 905-666-6215
Under the Health Protection and Promotion Act, Sec. 26 (reporting of carrier of
disease), all positive TSTs are reportable to Public Health. The Health Care Provider
reading the test results is responsible for reporting the positive TST even when
referring the patient to another provider or specialist for assessment or treatment.
Person with a positive TST
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A physical exam including symptom review**
Perform chest x-ray (CXR). The chest x-ray can be within the previous three months
unless the person is symptomatic.
Inform person to monitor for symptoms** of active TB disease
Further future skin testing is not recommended
If asymptomatic and CXR normal, discuss options for LTBI treatment with client. Refer
to Quick Reference – Assessment and Treatment of Latent Tuberculosis Infection.
Annual CXR not recommended for TB screening unless becomes symptomatic or
unless possible exposure occurs.
If person has symptoms** or an abnormal chest x-ray:
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Collect 3 sputum samples (either spontaneous or induced) which can be collected on
the same day, a minimum of 1 hour apart
Refer to Health Care Provider to conduct a medical assessment to rule out active TB if
active TB is suspected; inform the Health Care Provider's office ahead of time. Refer to
an Infectious Diseases specialist.
**Symptoms of infectious active TB include: fever, night sweats, chills, cough, a
productive cough with or without blood, loss of appetite, weight loss, chest pain, shortness
of breath, fatigue, and loss of energy
If person has no symptoms:

May continue to work while a Health Care Provider completes the assessment to rule
out active TB disease
Reportable Disease Notification Form and Infectious Diseases Prevention and Control
Tuberculosis Assessment Form are available at: durhamMD.ca
All forms can be faxed to Durham Region Health Department confidential fax at
905-666-6215
*REPORTING
Medication
The Durham Region Health Department provides education, counselling and monitoring of
active TB and latent TB infection (LTBI) for clients residing in Durham Region.
There are a number of pharmacies within Durham Region providing and dispensing free TB
medications to clients with active TB or LTBI.
Health Care Providers can fax prescriptions to a designated pharmacy location and direct
clients to pick up free TB medications at the agreed upon location. Free delivery is available if
required.
Medical Pharmacies Group Ltd Locations
Health Centre Pharmacy
Courtice Health Centre
1450 Hwy #2
Courtice, ON, L1E 3C3
Phone: 905-721-0011
Fax: 905-721-0770
Medical Pharmacy
Taunton Health Centre
1290 Keith Ross Court
Oshawa, ON, L1H 7K4
Phone: 905-434-1311
Fax: 905-434-7030
Medical Pharmacy
320 Byron Street South
Whitby, ON, L1N 4P8
Phone: 905-668-9393
Fax: 905-668-9632
Clinic Pharmacy
Oshawa Clinic
117 King Street East
Oshawa, ON, L1H 1B9
Phone: 905-576-9090 / 1-888-225-2265
Fax: 905-576-1533
Durham Pharmacy
462 Paxton Street
Port Perry, ON, L9L 1L9
Phone: 905-985-8484
Fax: 905-985-0827
Resources
durham.ca/TB
durhamMD.ca
User name: drhd
Password: health
Public Health Agency of Canada. (2013). Canadian Tuberculosis Standards, 7th Edition
The Lung Association. (2009). Tuberculosis Information for Health Care Providers, 4th Edition
The Lung Association, Toronto Public Health (2013). Quick Reference - Assessment and Treatment
of Latent Tuberculosis Infection.
MEDICATION/RESOURCES