TB in Children

Question 1

Why is paediatric TB particularly difficult to dx?

Answer 1

• Nonspecific s&s
• Paucibacillary (rare to get positive cultures)
• Dx LTBI can be challenging due to limited sens and spec of TST

Question 2

Indications for TST in children?

Answer 2

• Contacts of known cases of active TB
• Suspected active TB disease
• Known RFs for progression of infection to disease
• Residing > 3 months in area w/ high incidence TB
• Arrived in Canada from countries with high TB incidence in the past 2 years

Question 3

Downsides of TST?

Answer 3

Poor sensitivity (high FNs) in:
- Infants

Question 4

What is the IGRA? Advantages above the TST?

Answer 4

Measures in vitro production of IFN-gamma by lymphocytes in response to M. tuberculosis

• More specific than TST!
• Rapid turnaround time, single test

Question 5

In what situations should IGRA not be used?

Question 6

When should IGRA be used?

Answer 6

(1) To dx active TB (with TST)
- but neg TST/IGRA does not r/o TB, esp in young children

(2) To dx LTBI in
TST+ immunocompetent child with low likelihood of TB infx

(3) To dx LTBI in immunocompromised pt (with TST)

Question 7

Close contacts on an index TB case (or contacts with high risk of progression for active disease) - how to investigate for TB?

Answer 7

TST (or TST + IGRA) 8-12 weeks from most recent exposure

If either +, treat for LTBI

Question 8

Which immigrant children should get LTBI screening?

Answer 8

-

Question 9

High risk RFs for developing active TB in those infected?

Answer 9

• AIDS
• HIV infection
• Post-transplant
• Silicosis
• Chronic renal failure requiring HD
• H+N carcinoma
• Recent TB infection (

Question 10

RFs conferring increased risk for developing active TB?

Answer 10

• Steroids
• TNF alpha inhibitors
• DM
• Underweight (BMI