Approach to detecting TB in youth - CPS Statement

Question 1

What are the BCG contraindications?

Answer 1

BCG is contraindicated for infants with a family history of immunodeficiency or who are suspected of being immunodeficient

Question 2

What is the difference between a Ghon focus and Ghon complex?

Answer 2

The parenchymal site of infection with Mtb bacilli is a Ghon focus.

Ghon complex includes adjacent hilar lymphadenopathy.

Question 3

What percent of cases in children exposed to TB develop clinical disease?

Answer 3

5-10%

Question 4

Re-activation of latent TB disease occurs most often after what age?

Answer 4

10 years

Question 5

The majority of children exposed to TB who develop primary symptoms do so within ____ after exposure.

Answer 5

1 year

Question 6

What are the CXR findings for active TB?

Answer 6

Radiographs typically show focal pneumonitis or subtle ‘ground glass’ opacities, with (usually) hilar, mediastinal or subcarinal lymphadenopathy

Question 7

In TB meningitis, what does the CSF cell count typically show?

Answer 7

Cerebrospinal fluid (CSF) typically shows pleocytosis, with lymphocytic predominance.

Question 8

What are the risk factors for re-activation of latent TB in children?

Answer 8

Aside from likely host genetic factors, other risk factors include:
1) Immunosuppression (e.g., human immunodeficiency virus (HIV) infection or diabetes)
2) Malnutrition
3) Medications (especially steroids or biologics)

Question 9

In children who can’t produce sputum, how can you diagnose TB?

Answer 9

In children who cannot expectorate sputum, fasting gastric aspirates obtained on three consecutive mornings are useful for culture

Question 10

All patients with TB disease require serology for ____.

Answer 10

HIV

Question 11

A positive TST is a Type ___ hypersensitivity reaction.

Answer 11

Type IV

Question 12

What are the cut-offs for a positive TST in those who are immunocompromised or a close contact? What is the cut-off for everyone else?

Answer 12

≥5 mm induration for individuals who are immunocompromised and contacts of cases

≥10 mm for others

Question 13

How do the IGRA tests work?

Answer 13

Interferon-gamma release assays:
In-vitro blood tests that evaluate immune response by measuring the release of interferon-gamma by T-cells in response to antigens specific for Mtb

No cross-reactivity with BCG

Question 14

How do TST skin tests work?

Answer 14

Tuberculin is a purified protein derivative (PPD) from heat-inactivated Mtb.

When injected intradermally as a tuberculin skin test (TST), a type IV hypersensitivity reaction (wheal) occurs if the recipient has been infected with Mtb or if they have cross-reactive antigens from non-tuberculous mycobacteria (NTM) or from BCG vaccine

Question 15

Which test is more specific: TST or IGRA?

Answer 15

Specificity is >95% for an IGRA, compared with 60% for a TST

Question 16

Will an IGRA/TST be positive in latent disease?

Answer 16

Typically yes

Question 17

In children ≥2 years old, which test is more specific - IGRA or TST?

Answer 17

TST and IGRA were thought to have similar sensitivity and specificity for diagnosis of LTBI

Question 18

In children <2 years old, which test is likely more sensitive for TB?

Answer 18

TST is possibly more sensitive than IGRA.

Since this group is at higher risk for disease progression, the more sensitive TST is currently recommended over IGRA

Question 19

What are the initial steps when you have a patient identified as a contact of a positive TB person? (Hint: 4 steps)

Answer 19

1) Conducting a history and physical exam
2) Requesting chest radiographs
3) Performing an initial TST
4) Obtaining the index case’s drug sensitivities is also required

Question 20

Child contacts <5 years of age with a close contact and an initial TST of <5 mm should receive ____

Answer 20

Preventive prophylaxis (also known as ‘window prophylaxis’, with one TB drug), using a drug that has been identified as effective for treating the source case strain

Question 21

Child contacts <5 years of age with an initial TST of <5 mm require a repeat TB test at what interval?

Answer 21

Second TST at 8-10 weeks after last contact with infectious case

Question 22

A child ≥5 years old with a close contact and an initial TST <5 mm in size requires ____

Answer 22

Needs a BOC TST 8 to 10 weeks later, although window prophylaxis is not recommended in this age group.

Question 23

When can you discontinue window prophylaxis in a child <5 years with a close contact and TST <5 mm?

Answer 23

Child contacts <5 years old, with a BOC TST <5 mm in size at 8 to 10 weeks, can then have window prophylaxis discontinued

Question 24

Child contacts ≥5 years who have no symptoms and whose physical exam and chest radiographs appear normal, with an initial or BOC TST of ≥5 mm, should receive ____

Answer 24

Treatment for latent infection

Question 25

What is the regimen for treatment of latent infection?

Answer 25

Individuals with LTBI are usually treated with isoniazid, rifampin or rifapentin/isoniazid, in collaboration with local public health authorities