Fundamentals of Tuberculosis

Reported TB Cases United States, 1981-2001 28000 26000 24000 22000 20000 18000 16000 14000 12000 10000 1981 1985 1989 Year 1993 1997 2001

2

TB Case Rates, United States, 2001

3

D.C.

Rate: cases per 100,000

< 3.5 (year 2000 target) 3.6 - 5.6

> 5.6 (national average)

Trends in TB Cases in Foreign-born Persons, United States, 1986-2001 Percentage No. of Cases

4

10,000 8,000 6,000 4,000 2,000 0 1986 1988 1990 No. of Cases 1992 1994 1996 1998 2000 Percentage of Total Cases 60 50 40 30 20 10 0

TB Case Rates in U.S.-born vs. Foreign born Persons, United States, 1991-2001

5

40 30 20 10 0 1991 1993 U.S. Overall 1995 1997 U.S.-born 1999 Foreign-born 2001

Note: Case rates for 2000 and 2001 based on an extrapolation from the March 2000 U.S. Census Bureau Current Population Reports.

Completion of TB Therapy United States, 1993-1999 100 80 60 40 20 0 1993 1994 Completed 1995 1996 1997 1998 Completed in 1 yr or less

Note: Persons with initial isolate resistant to rifampin and children under 15 years old with meningeal, bone or joint, or miliary disease excluded.

1999

6

TB in the United States

• From 1953 to 1984, reported cases decreased by approximately 5.6% each year • From 1985 to 1992, reported cases increased by 20% • 25,313 cases reported in 1993 • Since 1993, cases are steadily declining 7

Transmission & Pathogenesis of TB

• Caused by

Mycobacterium tuberculosis

• Spread person to person through the airborne particles that contain

M. tuberculosis

, called droplet nuclei • Transmission occurs when an infectious person coughs, sneezes, laughs, or sings • Prolonged contact needed for transmission • 10% of infected persons will develop TB disease at some point in their lives 8

Common Sites of TB Disease

• Lungs (85% of all cases) • Pleura • Central nervous system • Genitourinary system • Bones and joints • Disseminated (miliary TB) 9

Not Everyone Exposed Becomes Infected

Probability of transmission depends on:

-

How Contagious - Kind of Environment - Length of Exposure 10

Development of TB Disease

• 10% of infected persons will develop TB disease at some point in their lives • Certain conditions increase the risk that TB infection will progress to disease 11

Factors Contributing to the Increase in TB Cases

• HIV epidemic • Increased immigration from high-prevalence countries • Transmission of TB in congregate settings (e.g., correctional facilities, long-term care) • Deterioration of the public health care infrastructure 12

Factors That Increase the Risk of TB Disease Once Infected

• HIV infection • Substance abuse (especially drug injection) • Recent infection with

M. tuberculosis

• Chest radiograph findings suggestive of previous TB (in a person inadequately treated) • Low body weight (10% or more below the ideal) • Certain Medical Conditions, such as…..

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Medical Conditions that Increase the Risk of TB Disease

• Diabetes mellitus • Silicosis • Cancer of the head and neck • Hematologic and reticuloendothelial diseases • End-stage renal disease • Intestinal bypass or gastrectomy • Chronic malabsorption syndromes • Prolonged corticosteroid therapy • Other immunosuppressive therapy 14

Groups at High Risk for TB Exposure

• Close contacts of a person with infectious TB • Foreign-born persons from areas where TB is common • Residents of congregate settings • Persons who inject drugs • Locally identified high-burden groups, such as farm workers or homeless persons • Children 15

Clinical Manifestations of TB

• Chest pain • Productive prolonged cough • Hemoptysis • Fever, chills, night sweats • Easy fatigability • Loss of appetite • Weight loss 16

TB Diagnostic Tests

• Mantoux Tuberculin Skin Test • Chest X-ray • Sputum examination 17

Latent TB Infection

(L TBI)

• Occurs when person inhales bacteria and it reaches air sacs (alveoli) of lung • Immune system keeps bacilli encapsulated • Person is not infectious and has no symptoms 18

TB Disease

• Occurs when immune system cannot keep bacilli contained • Bacilli begin to multiply • Person develops symptoms 19

LTBI vs. TB Disease

• LTBI – Asymptomatic – PPD negative – Chest X-ray normal – Sputum negative – Not infectious • TB Disease – Cough, fever, night sweats – PPD positive – Chest X-ray abnormal – Infectious before treatment initiated 20

Targeted Testing

• Not everyone should be routinely tested for TB • Testing should be done only if there is an intent to treat 21

Groups to Target with the Tuberculin Skin Test

• Persons with or at risk for HIV infection • Close contacts of persons with infectious TB • Persons with certain medical conditions • Persons who inject drugs • Foreign-born persons from areas where TB is common • Medically underserved, low-income populations • Residents of congregate settings • Locally identified high-prevalence groups 22

Performing the Tuberculin Skin Test

• Use Mantoux tuberculin skin test • 0.1 ml of 5-TU PPD injected intradermally • Read within 48-72 hours by healthcare worker • Measure transverse diameter of induration • Record results in millimeters of induration 23

Classifying the TST Reaction - 1

>5 mm is positive in

• Persons known to have or suspected of having HIV infection • Close contacts of a person with infectious TB • Persons who have a chest radiograph suggestive of previous TB • Persons who inject drugs (if HIV status unknown) 24

Classifying the TST Reaction - 2

> 10 mm is positive in

• Person with certain medical conditions, excluding HIV infection • Persons who inject drugs (if HIV negative) • Foreign-born persons from areas where TB is common • Medially underserved, low-income populations • Residents of long-term care facilities • Children younger than 4 years of age • Locally identified high-prevalence groups 25

Classifying the TST Reaction - 3

> 15 mm is positive in

• All persons with no known risk factors for TB 26

Classifying the TST Reaction - 4

For persons who may have occupational exposure to TB, the appropriate cutoff depends on: • Individual risk factors for TB • The prevalence of TB in the facility or place of employment 27

BCG Vaccination and Tuberculin Skin Test

28 • There is no reliable method of distinguishing tuberculin reaction caused by BCG from those caused by TB infection • Evaluate all BCG-vaccinated persons who have a positive skin test result for treatment of latent TB infection

Anergy

•

The inability to react to skin tests due to weakened immune system

• Do not rule out diagnosis of TB on basis of negative PPD • Consider anergy in non-reactors who: - Are immunocompromised (e.g., HIV+, cancer chemotherapy) - Have overwhelming TB disease 29

Boosting

• Some people with history of LTBI lose their ability to react to tuberculin • Baseline test may be negative (immune system “forgets” how to react to TB-like substance) • Another test 1-3 weeks later will be positive (baseline test stimulated/ “boosted” immune system) 30

Two-Step Testing

• A strategy for differentiating between boosted reactions and reactions caused by recent infections • 2nd test given 1 - 3 weeks after baseline • Used in many residential facilities for initial skin testing of new employees who will be re tested (with single test) on a regular basis 31

Two-Step Testing

Baseline PPD test Repeat PPD 1-3 weeks later

Negative Result

32 NEGATIVE: POSITIVE: Person probably does not This is a

“

boosted” reaction have TB infection due to TB infection a long time ago

Assessing Infectiousness of a TB Patient

• Patients should be considered infectious if they: – Are undergoing cough-inducing procedures – Have sputum smears positive for acid-fast bacilli and: • Are not receiving therapy • Have just started therapy, or • Have a poor clinical or bacterial response to therapy 33

Assessing Infectiousness of a TB Patient

• Patients are

not

considered infectious if they meet all these criteria: – Adequate therapy received for 2-3 weeks – Favorable clinical response to therapy, and – 3 consecutive negative sputum smears results from sputum collected on different days 34

Techniques to Decrease the Possibility of TB Transmission

• Instruct patient to: – Cover mouth when coughing or sneezing – Wear mask as instructed – Open windows to assure proper ventilation – Do not go to work or school until instructed by physician – Avoid public transportation – Limit visitors 35

Evaluation for TB

• Medical history • Physical examination • Mantoux tuberculin skin test • Chest radiograph • Bacteriologic exam (smear & culture) 36

Symptoms of TB

• *Productive prolonged cough • *Chest pain • *Hemoptysis • Fever • Chills • Night sweats • Easy fatigability • Loss of appetite • Weight loss *commonly seen in cases of pulmonary TB 37

Chest X-Ray

• Chest X-rays should be done in patients with positive skin test results • Abnormal chest X-ray cannot itself confirm the diagnosis of TB but can be used in conjunction with other diagnostic indicators 38

Sputum Collection

• Sputum specimens are essential to confirm TB • Mucus from within lung, not saliva • Collect 3 specimens on 3 different days • Spontaneous morning sputum more desirable than induced specimens • Collect sputum before drug therapy initiated 39

Smear Examination

• Strongly consider TB in patients with smears containing acid-fast bacilli (AFB) • Use follow-up smear examinations to assess patient’s infectiousness and response to therapy 40

Cultures

• Used to confirm diagnosis of TB • Culture all specimens, even if smear is negative • Initial drug isolate should be used to determine drug susceptibility 41

Treatment of Latent TB Infection

• Daily INH therapy for 9 months – Monitor patients for signs and symptoms of hepatitis and neurotoxicity • Alternate regimen – Rifampin for 4 months 42

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High Priority Candidates for Treatment of Latent TB Infection Regardless of age Over age 35

- HIV + or suspect - Foreign-born - Close contact - Medically underserved, - Abnormal chest x-ray low-income - Medical conditions - Long term care facilities - Recent converters - Other populations (homeless, HCWs)

Treatment of TB Disease

• Include four drugs in initial regimen – Isoniazid (INH) – Rifampin (RIF) – Pyrazinamide (PZA) – Ethambutol (EMB) • Adjust regimen when drug susceptibility results are shown • Never add a single drug to a failing regimen • Ensure adherence to therapy 44

Monitoring for Adverse Reactions

Instruct patients taking INH, RIF and PZA to report immediately the following: – nausea – loss of appetite – vomiting – persistently dark urine – yellowish skin – malaise – unexplained fever for 3 or more days – abdominal pain 45

Monitoring for Drug Resistance

• Primary - Becoming infected with a strain of

M. tuberculosis

which is already resistant to one or more drugs • Acquired - Becoming infected with a strain of

M. tuberculosis

which becomes drug resistant due to inappropriate or inadequate drug treatment 46

Barriers to Adherence

• Stigma • Extensive duration of treatment • Side effects of medications • Concerns of toxicity • Lack of knowledge of the disease process and necessary treatment 47

Improving Adherence

• Case management • Directly Observed Therapy (DOT) • Patient education • Incentives/enablers 48

Directly Observed Therapy (DOT)

• Health care worker watches patient swallow each dose of medication • DOT is the best way to ensure adherence • Should be used with all intermittent regimens • Reduces relapse of TB disease and acquired drug resistance 49

Other Measures to Promote Adherence

• Develop an individualized treatment plan for each patient • Work with outreach staff from same cultural and linguistic background as patient • Educate patient about TB, medication dosage, and possible adverse reactions • Use incentives and enablers to remove barriers to adherence • Facilitate access to health and social services 50