Characteristics of children with positive tuberculin skin test

Area of Science:

• Pediatrics
• Infectious Diseases
• Immunology

Background:

• Latent tuberculosis infection (LTBI) diagnosis in children presents challenges.
• The tuberculin skin test (TST) is a common diagnostic tool, but its interpretation can be affected by various factors.
• Identifying risk factors for positive TST in pediatric populations is crucial for accurate diagnosis and treatment.

Purpose of the Study:

• To characterize children diagnosed with latent tuberculosis infection using a positive TST.
• To evaluate potential risk factors influencing TST results in children.
• To assess the impact of demographic and clinical factors on TST reactivity in pediatric LTBI.

Main Methods:

• Retrospective study evaluating 81 children with positive TST.
• Data collection included patient demographics, medical history (atopy, respiratory infections, family history of TB/atopy), BCG vaccination status, and physical examination findings.
• Statistical analysis focused on factors affecting TST reaction size.

Main Results:

• Patient age, number of BCG vaccination scars, and BCG vaccination status significantly influenced TST reaction size.
• Factors such as time since last BCG, family history of TB, household contact with TB cases, smoking exposure, household size, and allergic respiratory disease did not significantly affect TST size.
• Only 16% of children with positive TST had known contact with an active TB case.

Conclusions:

• Pediatric TST results are significantly affected by patient age and BCG vaccination history (scars and vaccination status).
• These factors can complicate the diagnosis of LTBI and the decision to initiate prophylactic treatment in children.
• The study suggests that newer, more accurate in vitro tests, despite higher costs and laboratory requirements, may be valuable for diagnosing pediatric LTBI.