Tuberculosis

Descriptive text is not available for this imageBASICS

DESCRIPTION

  • Pediatric tuberculosis (TB) is the disease state caused by Mycobacterium tuberculosis (MTB), an acid-fast bacillus (AFB). Pediatric TB should be regarded as a spectrum of exposure, infection, and disease. Both the likelihood and speed of progression from TB infection to TB disease occur variably depending on age and immune status.
  • The progression through this spectrum varies by age. Disease progression is 40–50% within 1 to 6 months for children up to 1 year old, 20–30% for children 1 to 2 years old, ~5% for those 2 to 4 years old, and ~2% for those ≥5 years old. Five- to 10-year-old children are the most protected age group. Adolescents is another vulnerable age group with risk of TB disease of 10–20% following infection.

EPIDEMIOLOGY

  • The most common route of infection is via the respiratory tract. TB is spread from a person with disease by droplet nuclei that are inhaled by others. Children have paucibacillary disease and are less infectious. Infection occurs after close and prolonged contact with an adult or adolescent who has active untreated infectious disease, usually pulmonary TB, in a poorly ventilated space. However, there are people who develop TB without knowledge of an infectious contact.
  • Congenital infection occurs, although rarely, in the setting of an untreated mother in the last trimester of pregnancy.
  • Infection with the tubercle bacillus needs to be differentiated from disease (i.e., TB infection vs. TB disease).
  • The interval between onset of TB infection (previously called “latent TB”) and TB disease is usually 10 to 12 weeks. This interval is occasionally faster than 10 weeks and, not infrequently, may be significantly >12 weeks.
  • Following TB exposure, the greatest chance of infection occurring (i.e., of a positive result in tests using purified protein derivative [PPD], now renamed tuberculin skin test [TST]), is within the first 2 years after infection.
  • The rate of progression through the spectrum of pediatric TB (exposure–infection–disease) is age dependent for infants and children <5 years of age, (see “Description” section).
  • Postpubertal adolescents and immunosuppressed people including people with diabetes, HIV, chronic renal failure, the malnourished, and those taking immune modulators for any reason have higher risks for progression of infection to disease.

GENERAL PREVENTION

  • There are now several treatment regimens available for the treatment of TB infection in the absence of TB disease. The reader is referred to the Centers for Disease Control and Prevention (CDC) Web site in the “Additional Reading” section.
  • Preferred regimen is the one most likely to be completed by the child. In discussion with the family, this often entails choosing the shortest regimen.
  • Historically, isoniazid (isonicotinic acid hydrazide [INH]), 10 to 20 mg/kg/24 h PO (max 300 mg/24 h) is given daily as self-administered therapy for 9 months. If adherence is not anticipated, 2 times a week as directly observed therapy (DOT) at 20 to 40 mg/kg/24 h, with a maximum dose of 900 mg/24 h usually administered by a school nurse, child care worker, or the local TB control program, ideally without breaks in treatment, although the patient has 12 months to complete the course. If a break occurs near the end of treatment, it need not be restarted because such treatment is ~90% effective against development of active TB for 20 years in nonimmunosuppressed children. This recommendation prevents disease in the treated patient and, as a public health measure, interrupts transmission to contacts of that infected person with 90% efficacy.
  • The preferred regimen by many experts for adults and children ≥2 years old, is a once-weekly 3-month course of INH and rifapentine via DOT (12 doses total). The pill burden in younger children is substantial.
  • Another often preferred regimen including if case patient has INH-resistant but rifampicin-susceptible TB is 4 months of rifampin 15 to 20 mg/kg/24 h PO or IV (max 600 mg/24 h) by DOT (for a total of 120 doses).
  • Bacillus Calmette-Guérin (BCG) vaccine is recommended in the United States only for infants and children who test negative to TST and who are continually exposed to and cannot be separated from either (i) contagious adults or (ii) adults with TB that is resistant to both INH and rifampin.

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