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Screening and Treating Pediatric TB. David Hilmers, MD January 9, 2006. Epidemiology. Worldwide 8 million new cases (all ages) each year 3 million deaths per year US 1000 kids develop active TB each year Highest rates in minorities Texas is among highest states for new cases.

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Screening and treating pediatric tb l.jpg

Screening and Treating Pediatric TB

David Hilmers, MD

January 9, 2006

Epidemiology l.jpg

  • Worldwide

    • 8 million new cases (all ages) each year

    • 3 million deaths per year

  • US

    • 1000 kids develop active TB each year

    • Highest rates in minorities

    • Texas is among highest states for new cases

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Stages of TB

  • 1. Exposure

    • Contact with someone with pulmonary TB

    • Asx and has negative PPD

  • 2. Latent infection

    • TB present only in lungs

    • Asx

    • CXR with only calcifications/granulomas

    • Positive PPD

  • 3. TB disease

    • Clinical manifestations

    • Radiographic evidence of disease

Transmission l.jpg

  • Spread via respiratory route when someone with TB sneezes, laughs, talks

  • Kids get TB from adults and are less contagious because of lower TB burden

  • After growing in alveolar macrophages, 103 –104 organisms needed for + PPD

  • Spread via lymphatics to lymph nodes and to distant sites through bloodstream

  • If intact cellular immunity, spread is limited by production of granulomas = latent TB infection

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Latent Infection

  • 40% of infants develop TB disease within 2-12 months after initial infection

  • Targeted PPD testing recommended now

  • Risk factors include:

    • Foreign traveler, immigrant

    • Exposure to high-risk individual or one with TB

    • Consuming raw milk or unpasteurized cheese

    • Living in jail or shelter

    • Having been exposed to HIV-positive person or drug user

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Latent Infection Diagnosis

  • Medical history for sxs and exposures; attempt to find source case

  • PEX for signs of disease and CXR

  • Gastric aspirates in early am x 3

  • TB skin test still best method (sensitivity 80-96%)

  • Shows delayed hypersensitivity reaction induced by antigenic components of M. TB

  • Interpretation of results (next slide)

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Treatment of Latent TB

  • INH drug of choice if susceptible or susceptibility unknown

  • Evaluate for risk factors for INH-induced hepatitis, LFT’s NOT necessary

  • Daily rifampin is acceptable if sensitive and if INH not tolerated or INH resistance

  • B6 not needed unless there is risk factor for B6 deficiency (diabetes, uremia, HIV, alcoholism, low B6 in diet) or if breastfeeding

  • What is the duration of treatment?

  • 9 months

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TB disease

  • Test high-risk kids with PPD, 10% of immunocompetent kids with dz have false neg

  • TB of superficial lymph nodes is most common extrapulmonary manifestation

  • Fever is common but other systemic signs are often absent

  • CXR may show LAD, atelectasis, consolidation, densities, effusions or mass

  • Cavities are rare

  • Try to isolate by gastric aspirates but yield is only 50%

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Clinical Forms

  • Pulmonary

  • Disseminated most commonly miliary TB with massive release of bacilli into blood affecting at least 2 organs

  • CNS TB from formation of caseous granulomas in cerebral cortex during lymphohematogenous dissemination

  • Skeletal TB (Pott’s if in spine) also from lymphohematogenous dissemination

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  • Drug susceptible

    • 2 months of INH, RIF, and PZA

    • 4 months of INH and RIF qD or twice weekly

  • If areas of low-resistance

    • 1 month of INH and RIF daily

    • 8 months of INH and RIF qD or twice weekly

  • Extrapulmonary TB treated the same except tuberculous meningitis

  • TB meningitis

    • 2 months INH, RIF, PZA, and either ethambutol or streptomycin

    • 7-10 months INH and RIF qD or twice weekly

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Treatment Complications

  • Few side effects, most common is hepatotoxicity from INH

  • NO LFT’s needed at baseline unless sxs develop (abdominal pain, icterus, e.g.) or if coexisting conditions (HIV, drug abuse) or hepatotoxic meds (anticonvulsants)

  • INH can cause peripheral neuropathy, neuritis, ataxia, seizures

  • RIF can cause hepatitis and may inhibit effectiveness of OCP’s, should use alternate form of birth control

  • Streptomycin affects the vestibular and auditory portions of 8th cranial nerve

  • Ethambutol can cause optic neuritis

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But I’ve had the BCG vaccine!

  • 16 yo female from Guatemala presents with fever, cough, and malaise for several weeks. You are concerned about pulmonary TB. Her shot record indicates she received the BCG vaccine. Do you place a PPD on this patient?

  • Yes

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BCG Vaccination

  • Attenuated strain of M. bovis

  • Used world-wide except in US

  • Efficacy is 52%, seemingly more effective in extrapulmonary TB

  • Given in US only if negative PPD and cannot be treated for LTBI but are at high risk of continuous exposure to TB

  • In patients who have had BCG vaccine, PPD should be interpreted similarly to those who have not been vaccinated

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Case 1

  • A 9 month old male, born in the US to a family from Mexico, has been visiting his grandmother who has been recently dx’d with pulmonary TB.

  • He is asymptomatic, has a normal exam. His PPD and CXR are negative.

  • Does he require any further testing?

  • Yes, repeat PPD in 12 weeks. After exposure, it can take 2-12 weeks for bacteria to grow to significant levels to cause an immune response/PPD conversion

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Case 2 - Serial Testing

  • 2a - 26 yo intern had a PPD placed but missed his/her f/u for reading due to falling asleep post-call. The intern did take note that the test was negative. They return to Occupational Health the next week to have the PPD placed again. Can serial TB testing induce a positive PPD?

  • Depends…did the intern have a past positive ppd.

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Booster Effect

  • PPD skin sensitivity persists throughout life

  • Over time, the size of the skin test can decrease and may disappear.

  • If a PPD comes back small or absent in a previously infected person, then there can be an accentuation of a response on repeat testing.

  • This can be misinterpreted as a skin test conversion if the history is not correctly taken.

  • Repeated testing on persons with no cellular immunity to the antigens in PPD will not induce a conversion.

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How well do you know TB?

  • What does PPD stand for?

  • purified protein derivative

  • What does BCG stand for?

  • bacillus Calmette-Guerin - named after the two French investigators who developed the vaccine