Contact Assessment

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Contact Assessment

• Contact Assessment and Tuberculosis Skin Testing
  (TST)

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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

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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).

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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?

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Assessment of a contact cont

• 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.

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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

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Referral for sputum cont

• 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

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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

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High risk conditions when associated with TB
contact

• HIV
• AIDS
• Transplantation (related to immunosuppressant
  therapy)
• Silicosis
• Chronic renal failure requiring hemodialysis

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Hi Risk Conditions Cont

• Carcinoma of the head and neck
• Recent TB infection (lt 2 years)
• Abnormal chest x-ray fibronodular disease
• Treatment with glucocoriticoids

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Increased risk conditions

• Tumor necrosis factor alpha (TNF) antagonists
• infliximab (Remicade)
• etanercept (Enbrel)
• adalimumab (Humira)

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Increased risk conditions

• Diabetes mellitus
• Underweight lt90 ideal body weight
• Young age when infected(0-4yrs)
• Cigarette smoker
• Abnormal chest x-ray - granuloma

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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

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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

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Contraindications

• Do not test people who
• Have a documented TST result gt 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

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Common Side Effects

• Pain
• itchiness
• discomfort at the test site may occur
• Treat with cool cloths or ice. Do not scratch.

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Severe side effects

• Blistering
• Ulcers
• Necrosis
• Scarring from strongly positive reactions
• Anaphylactic reaction

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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

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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

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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.

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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

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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

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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

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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

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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)

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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

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Only the induration is being measured. This is
CORRECT.
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The erythema is being measured. This is
INCORRECT.
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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

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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 persons risk
  factors for TB

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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 x-ray)

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Definition of a significant (positive)TST

• gt5 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

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Definition of a significant (positive)TST

• gt 10 or more millimeters (mm)
• All other persons

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Recording TST results

• Record the size of the induration in millimeters
• Dont write negative or neg but record as 0
  mm
• Dont write positive or pos, but record the
  actual measurement

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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

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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

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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.

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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

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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)

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False negative continued

• Technique
• Improper storage
• Adsorption
• Poor injection technique
• Failure to detect/interpret induration

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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.

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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.

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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

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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 lt10mm two step
  baseline with in the last year, we will not know
  when this infection occurred.

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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.

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Referral for CXR

• Contacts with significant reactions
• Contacts with symptoms consistent with TB
  regardless of reaction
• Contacts lt5 years of age
• Immuno-suppressed/HIV contacts

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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

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References

• Curry International Tuberculosis Center
• Canadian Tuberculosis Standards 6th edition
• Canadian Immunization Guide 7th edition
• Manitoba Health Tuberculosis Protocol December
  2009