Transcript No Slide Title

Contact Assessment
Contact Assessment
and Tuberculosis
Skin Testing (TST)
Disclosure of
Potential for
Conflict of Interest
M. Ruth Deane RN BN
Communicable Disease Coordinator
FINANCIAL DISCLOSURE
Grants/Research Support: none
Speakers Bureau/Honoraria: none
Consulting Fees: none
Purpose of the TB
Investigations
Tuberculosis (TB) contact investigations are
undertaken to evaluate and follow-up close contacts
of active cases, in order to identify secondary cases
with active disease, and to identify and treat those
with latent tuberculosis infection (LTBI).
Assessment of a
Contact
Symptom review
•
The following questions should
be asked:
-
Do you have a cough right now? Has this
cough lasted longer than three weeks?
Have you coughed up any blood?
Have you lost any weight? Were you
trying to loose weight?
Do you have any fever?
Assessment of a
contact con’t
- Do you have night sweats? If yes, is there a
known cause? (I.e. menopause, note as a
symptom and also note the attributable
cause)
- Do you have any pain with breathing?
- Are you fatigued?
If any symptom was present, but has since
completely resolved, mark as ‘absent’ but
with a brief note regarding when they
occurred and how long they lasted.
Referral for Sputum
Any contact with a cough lasting
three weeks or longer
Should advise those without a
cough, but with other symptoms
of TB, that we may send for
induced sputum based on CXR
results
Referral for sputum
con’t
Need to provide specimen
containers and instructions
Need three samples, at least one
should be early morning
Need to be refrigerated until
delivered to the laboratory
TB History
Have you ever had TB?
•
Need documented history of fully
treated disease
Have you ever had a Tuberculin
Skin Test?
•
Need documented result, if not
documented, repeat
High risk conditions
when associated with
TB contact
HIV***
AIDS***
Transplantation (related to
immunosuppressant therapy)
Silicosis
Chronic renal failure requiring hemodialysis
Hi Risk Conditions
Cont
Carcinoma of the head and neck
Recent TB infection (< 2 years)
Abnormal chest x-ray fibronodular
disease
Treatment with glucocoriticoids
Increased risk
conditions
Tumor necrosis factor alpha (TNF)
antagonists
infliximab (Remicade)
• etanercept (Enbrel)
• adalimumab (Humira)
•
Increased risk
conditions
Diabetes mellitus
Underweight <90% ideal body
weight
Young age when infected(0-4yrs)
Cigarette smoker
Abnormal chest x-ray - granuloma
The tuberculin skin test
Different types of tuberculin tests are
available
The Mantoux (intradermal) tuberculin skin
test is the preferred type because it is
the most accurate
The tuberculin used in the skin test is also
known a s Purified protein derivative or
“PPD”
Storage and handling
of Tuberculin
•
•
•
•
•
Date and initial when vial is opened
Discard 30 days after opening
It is sensitive to light, keep out of light
Draw up just prior to injection
Store at 2 to 8 degrees C° in a
refrigerator or cooler with ice packs
Contraindications
Do not test people who:
• Have a documented TST result > 10 mm
• Have had TB disease in the past, confirmed
• Have had severe blistering TST reactions in
the past
• Have severe eczema
• Have a history of anaphylactic reaction to past
TST
Common
Side Effects
•
Pain
• itchiness
• discomfort at the test site may occur
Treat with cool cloths or ice. Do not
scratch.
Severe side effects
•
•
•
•
•
Blistering
Ulcers
Necrosis
Scarring from strongly positive reactions
Anaphylactic reaction
Dosage and
Administration
Site:
• Left inner aspect of the forearm 2-4 inches
below the elbow.
• Avoid areas with abrasions, swelling, visible
veins or lesions that will make TST results
difficult to interpret.
• Cleanse skin with alcohol swab and allow to
dry
Dosage and
Administration
Dose:
0.1 ml of 5 TU (Tuberculin Units) of Tuberculin
Purified Protein Derivative (Mantoux)
Manufactured by Aventis Pasteur, trade name
Tubersol
Supplied by Manitoba TB Control Program for
contact testing and select screening
programs only
Dosage and
Administration
Route:
• Intradermally with a 27 gauge, ½ inch
needle and 1ml syringe.
• Hold skin of the forearm tautly.
• Insert needle with bevel up at a 10-15
degree angle just until the bevel
disappears under the skin.
Dosage and
Administration
•
•
•
•
Slowly inject 0.1 ml Tubersol until
activation of safety mechanism
Look for a discrete, pale elevation of
the skin (wheal)
Wheal should measure 6-10 mm in
diameter
Do not massage the site or cover site
with a bandage
Dosage and
Administration
If solution leaks from the site or no wheal
appears:
• TST will be inaccurate
• Repeat injection at least two inches
from the first TST or on the other
forearm
Timing of
administration
“TST conversion occurs within 8 weeks of
exposure and infection. The traditional
concept was that conversion occurred in
up to 12 weeks. However, all available
experimental and epidemiologic
evidence consistently shows that this
interval is less than 8 weeks.” CTS p 67
How is the skin test
read?
Test is read by a trained health worker
48 - 72 hours after the tuberculin injection
Read the TST in good light (may want to
bring a pen light) with the forearm
supported on a firm surface and the elbow
slightly flexed.
Reposition as necessary if interpretation is
difficult
How is the skin test
read?
Diameter of the indurated (swelling)
area is measured across the forearm
Erythema (redness) is not measured
Test result is measured in millimeters
(mm)
How is the skin test
read?
Find induration by looking at site from the
side and then by direct palpation. Mark
edges of induration with a pen
Also, using a ballpoint pen, draw a line from
the outer edge of the arm inward toward
the induration, and stop when the pen
comes against the border, repeat from the
other side
Only the induration is being measured.
This is CORRECT.
The erythema is being measured.
This is INCORRECT.
Routine Practices for
TST reading
Wash hands with waterless hand
gel or water between clients
Cleanse ruler with alcohol swab
between readings
Ensure ‘cover your cough’ policy
is enforced
What makes the
reaction significant?
Whether a reaction to the TST is
classified as significant, depends on the
size of the induration (swelling) and the
person’s risk factors for TB
Definition of a
significant
(positive)TST
0-4 mm HIV infection with immune
suppression and the expected
likelihood of TB infection is high
(e.g. close contact; abnormal xray)
Definition of a
significant
(positive)TST
>5 or more millimeters (mm)
• Contact to an infectious case of TB
• Immunocompromised persons including
HIV infection
• Person with an abnormal chest
radiograph, but no evidence of active
TB
Definition of a
significant
(positive)TST
> 10 or more millimeters (mm)
• All other persons
Recording TST
results
Record the size of the induration in
millimeters
Don’t write ‘negative’ or ‘neg’ but record
as 0 mm
Don’t write ‘positive’ or ‘pos’, but record
the actual measurement
Factors that can
cause a false positive
reading
•
•
•
•
•
Infection with non-tuberculosis
mycobacterium
Vaccination with BCG
Allergic reaction to bandage/tape used
to cover TST
Improper administration of TST
Failure to measure induration correctly
BCG can be ignored as
cause of false positive
if:
•
•
•
Was given in infancy and the person
tested is now 10 years or older
There is a high probability of TB infection
(close contact; high risk community or
country of origin)
There is a high risk of progression from
infection to disease
BCG should be
considered likely cause
of a positive TST if:
•
Was given after 12 months of age
AND the person is either Canadian –
born non Aboriginal OR an immigrant
/visitor from a low TB incidence
country.
BCG Scar
Presence of scar indicates that the vaccination
‘took’ or was effective and should be
documented.
BCG is administered on the left (usually)
shoulder in Manitoba
Other sites include the leg and back
Smallpox vaccination last given in 1970 in
Manitoba. No documentation found for other
countries
Factors that can cause
a false negative reading
•
Immune suppression due to:
• Advanced age
• Treatment with corticosteroids
• Cancer therapy agents
• HIV infection
• Possible tumor necrosis alfa inhibitors
• Malnutrition
• Severe illness, including active TB
• Major viral illness or immunization within 4 weeks with
MMR, varicella or yellow fever vaccine
• Very young age (less than six months)
False negative
continued
Technique:
• Improper storage
• Adsorption
• Poor injection technique
• Failure to detect/interpret induration
What is a “boosted”
reaction to a TST
Some persons infected with TB in the past
lose their ability to react quickly to TST
A first TB test may be (falsely) negative
Another test, one week or more later (up to
one year) will show a (true) positive
reaction.
Why do we not do a
‘two-step” in contact
investigations?
In contact investigations, the ‘contact’
(I.e. breathing in the TB bacilli) is the
‘first step’. Therefore only one TST is
needed to identify past infection.
Why do we not do a
‘two-step” in contact
investigations?
Two TSTs are done in some
investigations based on time since last
contact, ie need at least 8 weeks to
develop a reaction.
Some of the contacts who are positive on
the second test, will be due to a boosted
reaction.
Referral for assessment and treatment of
LTBI is necessary regardless
So what does a
‘significant’ reaction
mean?
We must assume, in the absence of a
more definitive test, that a significant
reaction indicates tuberculosis
infection.
In the absence of a documented <10mm
two step baseline with in the last year,
we will not know when this infection
occurred.
So what does a
‘significant’ reaction
mean?
Approximately 5% of immunocompetent
newly infected persons will develop
primary or progressive primary disease
within 18 – 24 months. Those who do
not develop primary disease have a 5%
chance of reactivation or post primary
TB at some time in their lives.
Referral for CXR
•
•
•
•
Contacts with significant reactions
Contacts with symptoms consistent with
TB regardless of reaction
Contacts <5 years of age
Immuno-suppressed/HIV contacts
Where, how, who
makes the referral?
CXR requisition given
Sputum collected as necessary
Results are sent directly to 496 Hargrave
Contacts are referred to either Klinic,
Health Action Centre, Childrens Hospital
or Respiratory Outpatients Clinic for
assessment and treatment of LBTI
References
Curry International Tuberculosis Center
Canadian Tuberculosis Standards 6th edition
Canadian Immunization Guide 7th edition
Manitoba Health Tuberculosis Protocol
December 2009