TB Disease and Latent TB Infection

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TB Disease and Latent TB Infection

• Karen Galanowsky RN, MPH
• Nurse Consultant, TB Program
• New Jersey Department of Health Senior Services

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Transmission of M. tuberculosis

• Spread by droplet nuclei
• Expelled when person with infectious TB coughs,
• sneezes, speaks, or sings
• Close contacts at highest risk of becoming
• infected
• Transmission occurs from person with infectious
• TB disease (not latent TB infection)

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Latent TB Infection (LTBI)

• LTBI is the presence of M. tuberculosis
• organisms (tubercle bacilli) without
• symptoms or radiographic evidence of TB
• disease
• With LTBI, the person is healthy and cannot
  spread TB to anyone

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Testing for M. tuberculosis Infection

• Mantoux tuberculin skin test (TST)
• Skin test that produces delayed-type
  hypersensitivity reaction in persons with M.
  tuberculosis infection
• Use a cut point of 5mm or 10 mm depending upon
  the reason for testing
• QuantiFERON -TB Gold Test
• Blood test that measures and compares amount of
  interferon-gamma (IFN-?) released by blood cells
  in response to TB antigens

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Persons at Risk for DevelopingTB Disease
Persons at high risk for developing TB disease
fall into 2 categories

• Those who have been recently infected
• Those with clinical conditions that increase
  their risk of progressing from LTBI to TB disease
• HIV
• Uncontrolled diabetes
• Cancer of the head or neck
• TNF-alpha blockers

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Targeted Tuberculin Testing

• Detects persons with LTBI who would benefit from
  treatment
• De-emphasizes testing of groups that are not at
  high risk for TB
• Can help reduce the waste of resources and
  prevent inappropriate treatment

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When TB Disease Develops Symptoms

• Prolonged cough
• Night sweats
• Loss of appetite
• Weight loss
• Fatigue
• Fever
• Chills
• Coughing up blood
• Chest pain

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Evaluation for TB

• Medical history
• Physical examination
• Mantoux tuberculin skin test or Quantiferon-TB
  Gold
• Chest radiograph
• Bacteriology testing for smear and culture
  identification

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Common Sites of TB Disease

• Lungs
• Pleura
• Central nervous system
• Lymphatic system
• Genitourinary systems
• Bones and joints
• Disseminated (miliary TB)

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Principles of Treatment for TB Disease

• Treatment for TB disease is usually 6 9 months
• The four first-line drugs should be used
  initially until drug susceptibility studies are
  determined.
• Dosages should be calculated based on weight
  (mg/kg)
• All TB medications should be ingested together
  the approximately at the same time daily
• TB medications may be given intermittently (twice
  or thrice weekly by directly observed therapy
  after the initial phase of treatment.

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MDR and XDR-TB

• MDR-TB - Mycobacterium TB that is resistant to at
  least Isoniazid and Rifampin
• XDR TB is defined as resistance to the four
  first-line drugs, an injectable, and one of the
  quinolones
• Individuals with XDR TB are more likely to die
  during treatment or have treatment failure
• XDR TB has emerged worldwide as a threat to
  public health and TB control raising concerns for
  a future epidemic of virtually untreatable TB
• Second-line anti-TB medications are used in the
  treatment of MDR and XDR-TB. These are costly,
  difficult to administer, and cause serious side
  effects

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Factors that Affect TB Transmission

• Infectiousness of person with TB
• Environment in which exposure occurred
• Duration of exposure
• Proximity to the infectious person