TB Disease and Latent TB Infection

Karen Galanowsky RN, MPHNurse Consultant, TB Program

New Jersey Department of Health & Senior Services

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

• 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

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

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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

When TB Disease Develops Symptoms

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

Evaluation for TB

• Medical history

• Physical examination

• Mantoux tuberculin skin test or Quantiferon-TB Gold

• Chest radiograph

• Bacteriology testing for smear and culture identification

Common Sites of TB Disease

•Lungs

•Pleura

•Central nervous system

•Lymphatic system

•Genitourinary systems

•Bones and joints

•Disseminated (miliary TB)

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.

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

Factors that Affect TB Transmission

•Infectiousness of person with TB

•Environment in which exposure occurred

•Duration of exposure

•Proximity to the infectious person