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Targeted Tuberculin Testing and Treatment of Latent Tuberculosis Infection, 2005

Slide 1: Targeted Tuberculin Testing and Treatment of Latent Tuberculosis Infection, 2005

Applying CDC/ATS Guidelines in Your Clinical Practice
Division of Tuberculosis Elimination
Centers for Disease Control and Prevention

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Slide 2: Targeted Tuberculin Testing and Treatment of Latent Tuberculosis Infection

As tuberculosis (TB) disease rates in the United States (U.S.) decrease, finding and treating persons at high risk for latent TB infection (LTBI) has become a priority.

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Slide 3: Latent TB Infection (LTBI)

LTBI is the presence of M. tuberculosis organisms (tubercle bacilli) without symptoms or radiographic evidence of TB disease.

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Slide 4: Terminology

• “Treatment of latent TB infection” replaces the terms “preventive therapy” and “chemoprophylaxis” to promote greater understanding of the concept for both patients and providers.
• Targeted tuberculin testing is used to focus program activities and provider practices on groups at the highest risk for TB.

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Slide 5: LTBI vs. Pulmonary TB Disease

Latent TB Infection

• TST* or QFT^† positive
• Negative chest radiograph
• No symptoms or physical findings suggestive of TB disease

Pulmonary TB Disease

• TST or QFT usually positive
• Chest radiograph may be abnormal
• Symptoms may include one or more of the following: fever, cough, night sweats, weight loss, fatigue, hemoptysis, decreased appetite
• Respiratory specimens may be smear or culture positive

* tuberculin skin test
^† QFT (QuantiFERON-TB and QuantiFERON-Gold) is a blood test to detect M. tuberculosis infection.

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Slide 6: 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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Slide 7: Treatment of LTBI – Milestones (1)

For more than 3 decades, an essential component of TB prevention and control in the U.S. has been the treatment of persons with LTBI to prevent TB disease.

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Slide 8: Treatment of LTBI – Milestones (2)

1965: American Thoracic Society (ATS) recommends treatment of LTBI for those with previously untreated TB, tuberculin skin test (TST) converters, and young children.

1967: Recommendations expanded to include all TST positive reactors (> 10 mm).

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Slide 9: Treatment of LTBI – Milestones (3)

1974: CDC and ATS guidelines established for pretreatment screening to decrease risk of hepatitis associated with treatment

• Treatment recommended for persons < 35 years of age

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Slide 10: Treatment of LTBI – Milestones (4)

1983: CDC recommends clinical and laboratory monitoring of persons > 35 who require treatment for LTBI

1998: CDC recommends 2 months of rifampin (RIF) plus pyrazinamide (PZA) as an option for HIV-infected patients (later changed)

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Slide 11: Treatment of LTBI – Milestones (5)

2000: CDC and ATS issue updated guidelines for targeted testing and LTBI treatment¹

• 9-month regimen of isoniazid (INH) is preferred
• 2-month regimen of RIF and PZA and a 4-month regimen of RIF recommended as options (later changed)

¹ MMWR June 9, 2000; 49(No. RR-6)

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Slide 12: Treatment of LTBI – Milestones (6)

2001: Owing to liver injury and death associated with 2-month regimen of RIF and PZA, use of this option de-emphasized in favor of other regimens²

2003: 2-month regimen of RIZ and PZA generally not recommended — to be used only if the potential benefits outweigh the risk of severe liver injury and death³

² MMWR August 31, 2001; 50(34): 733-735

³ MMWR August 8, 2003; 52(31): 735-739

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Slide 13: What’s New (1)

Tuberculin skin testing

• Emphasis on targeting persons at high risk
• 5-mm induration cutoff level for organ transplant recipients and other immunosuppressed patients being treated with prednisone or TNF-a antagonists⁴
• Skin-test conversion defined as increase of > 10 mm of induration within a 2-year period, regardless of age

⁴ MMWR August 61, 2004; 53(33): 683-686

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Slide 14: What’s New (2)

Treatment of LTBI

• HIV-negative persons – INH for 9 months preferred regimen
• HIV-positive persons and those with fibrotic lesions on chest x-ray (consistent with previous TB) – INH should be given for 9 months
• For all persons – RIF for 4 months is an option

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Slide 15: What’s New (3)

Clinical and laboratory monitoring

• Routine baseline and follow-up monitoring not required except for
  • HIV-infected persons
  • Pregnant women or those in early postpartum period
  • Persons with chronic liver disease or who use alcohol regularly
• Monthly monitoring for signs or symptoms of possible adverse effects

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Slide 16: Identifying Risk Factors That Lead to Development of TB Disease

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Slide 17: Persons at Risk for Developing TB 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

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Slide 18: Recent Infection as a Risk Factor (1)

Persons more likely to have been recently infected include

• Close contacts to person with infectious TB
• Skin test converters (within past 2 years)
• Recent immigrants from TB-endemic regions of the world (within 5 years of arrival to the U.S.)

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Slide 19: Recent Infection as a Risk Factor (2)

• Children < 5 years with a positive TST
• Residents and employees of high-risk congregate settings (e.g., correctional facilities, homeless shelters, health care facilities)

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Slide 20: Increased Risk for Progression to TB Disease (1)

Persons more likely to progress from LTBI to TB disease include

• HIV-infected persons
• Those with a history of prior, untreated TB or fibrotic lesions on chest radiograph

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Slide 21: Increased Risk for Progression to TB Disease (2)

• Underweight or malnourished persons
• Injection drug users
• Those receiving TNF-a antagonists for treatment of rheumatoid arthritis or Crohn’s disease

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Slide 22: Increased Risk for Progression to TB Disease (3)

• Persons with certain medical conditions such as
  • Silicosis
  • Diabetes mellitus
  • Chronic renal failure or on hemodialysis
  • Solid organ transplantation (e.g., heart, kidney)
  • Carcinoma of head or neck
  • Gastrectomy or jejunoilial bypass

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Slide 23: Tuberculin Testing

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Slide 24: Testing for M. tuberculosis Infection

Mantoux tuberculin skin test (TST)

• Skin test that produces delayed-type hypersensitivity reaction in persons with M. tuberculosis infection

QuantiFERON^® -TB test and QuantiFERON^® - Gold

• Blood test that measures and compares amount of interferon-gamma (IFN-g) released by blood cells in response to antigens

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Slide 25: Mantoux Tuberculin Skin Test

• Preferred method of skin testing for M. tuberculosis infection
• TST is useful for
  • Determining how many people in a group are infected (e.g., contact investigation)
  • Examining persons who have symptoms of TB
• Multiple puncture tests (e.g., Tine Test) are inaccurate and not recommended

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Slide 26: Administering the TST

• Inject 0.1 ml of 5 TU PPD tuberculin solution intradermally on volar surface of lower arm using a 27-gauge needle
• Produce a wheal 6 to 10 mm in diameter

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Slide 27: Reading the TST (1)

• Measure reaction in 48 to 72 hours
• Measure induration, not erythema
• Record reaction in millimeters, not “negative” or “positive”
• Ensure trained health care professional measures and interprets the TST

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Slide 28: Reading the TST (2)

• Educate patient and family regarding significance of a positive TST result
• Positive TST reactions can be measured accurately for up to 7 days
• Negative reactions can be read accurately for only 72 hours

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Slide 29: TST Interpretation (1)

5-mm induration is interpreted as positive in

• HIV-infected persons
• Close contacts to an infectious TB case
• Persons with chest radiographs consistent with prior untreated TB

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Slide 30: TST Interpretation (2)

5-mm induration is interpreted as positive in (cont.)

• Organ transplant recipients
• Other immunosuppressed patients (e.g., those taking the equivalent of >15 mg/d of prednisone for 1 month or those taking TNF-a antagonists)

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Slide 31: TST Interpretation (3)

10-mm induration is interpreted as positive in

• Recent immigrants
• Injection drug users
• Residents or employees of congregate settings
• Mycobacteriology laboratory personnel

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Slide 32: TST Interpretation (4)

10-mm induration is interpreted as positive in (cont.)

• Persons with clinical conditions that place them at high risk
• Children < 4 years; infants, children, and adolescents exposed to adults at high-risk

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Slide 33: TST Interpretation (5)

15-mm induration is interpreted as positive in

• Persons with no known risk factors for TB.*

*Although skin testing programs should be conducted only among high-risk groups, certain individuals may require TST for employment or school attendance. Diagnosis and treatment of LTBI should always be tied to risk assessment.

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Slide 34: Factors That May Cause False-Positive TST Reactions

• Nontuberculous mycobacteria
  • Reactions caused by nontuberculous  mycobacteria are usually < 10 mm of induration
• BCG vaccination
  • Reactivity in BCG vaccine recipients generally wanes over time; positive TST result is likely due to TB infection if risk factors are present

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Slide 35: Factors That May Cause False-Negative TST Reactions (1)

• Anergy
  • Inability to react to a TST because of a weakened immune system
  • Usefulness of anergy testing in TST-negative persons who are HIV infected has not been demonstrated

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Slide 36: Factors That May Cause False-Negative TST Reactions (2)

• Recent TB infection
  • Defined as 2 to 10 weeks after exposure
• Very young age
  • Newborns

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Slide 37: Factors That May Cause False-Negative TST Reactions (3)

• Live-virus vaccination
  • For example, measles or smallpox
  • Can temporarily suppress TST reactivity
• Overwhelming TB disease
• Poor TST administration technique
  • For example, TST injection too shallow or too deep, or wheal is too small

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Slide 38: Boosting

• Some people with LTBI may have a negative skin test reaction when tested years after infection because of a waning response.
• An initial skin test may stimulate (boost) the ability to react to tuberculin.
• Positive reactions to subsequent tests may be misinterpreted as new infections rather than “boosted” reactions.

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Slide 39: Two-Step Testing (1)

• A strategy to determine the difference between boosted reactions and reactions due to recent infection.
  • If first TST is positive, consider the person infected
  • If first TST is negative, give second TST 1–3 weeks later
  • If second TST is positive, consider the person infected
  • If second TST is negative, consider the person uninfected at baseline

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Slide 40: Two-Step Testing (2)

• Use two-step tests for initial baseline skin testing of adults who will be retested periodically (e.g., health care workers).

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Slide 41: QuantiFERON^®-TB Test and QuantiFERON^®-Gold Test (1)

• Whole-blood test used to detect M. tuberculosis infection
• Approved by the U.S. Food and Drug Administration (FDA)
• Entails mixing blood samples with antigens from M. tuberculosis, M. avium complex, and controls and incubating for 16 to 24 hours

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Slide 42: QuantiFERON^®-TB Test and QuantiFERON^®-Gold Test (2)

• Cells that recognize the antigen release  interferon-g
• Amount of interferon released in response to tuberculin is compared to amount released in response to other antigens⁵

⁵ MMWR January 31,2003; 52 (RR-02): 15-18 and CDC Fact Sheet Document # 250103, March 2003

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Slide 43: LTBI Treatment Regimens

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Slide 44: Initiating Treatment

Before initiating treatment for LTBI

• Rule out TB disease (i.e., wait for culture result if specimen obtained)
• Determine prior history of treatment for LTBI or TB disease
• Assess risks and benefits of treatment
• Determine current and previous drug therapy

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Slide 45: Isoniazid Regimens (1)

• 9-month regimen of isoniazid (INH) is the preferred regimen
• 6-month regimen is less effective but may be used if unable to complete 9 months
• May be given daily or intermittently (twice weekly)
  • Use directly observed therapy (DOT) for intermittent regimen

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Slide 46: Isoniazid Regimens (2)

• INH daily for 9 months
        (270 doses within 12 months)
• INH twice/week for 9 months
        (76 doses within 12 months)
• INH daily for 6 months
        (180 doses within 9 months)
• INH twice/week for 6 months
        (52 doses within 9 months)

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Slide 47: Rifampin Regimens (1)

• Rifampin (RIF) given daily for 4 months is an acceptable alternative when treatment with INH is not feasible.
• In situations where RIF cannot be used (e.g., HIV-infected persons receiving protease inhibitors), rifabutin may be substituted.

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Slide 48: Rifampin Regimens (2)

• RIF daily for 4 months
        (120 doses within 6 months)
• RIF and PZA for 2 months should generally not be offered due to risk of severe adverse events⁶

⁶ MMWR August 8, 2003; 52 (31): 735-739

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Slide 49: Completion of Therapy

Completion of therapy is based on the total number of doses administered, not on duration alone.

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Slide 50: Management of Patient Who Missed Doses

• Extend or re-start treatment if interruptions were frequent or prolonged enough to preclude completion
• When treatment has been interrupted for more than 2 months, patient should be examined to rule out TB disease
• Recommend and arrange for DOT as needed

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Slide 51: Monitoring During Treatment

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Slide 52: Clinical Monitoring (1)

Instruct patient to report signs or symptoms of adverse drug reactions

• Rash
• Anorexia, nausea, vomiting, or abdominal pain in right upper quadrant
• Fatigue or weakness
• Dark urine
• Persistent numbness in hands or feet

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Slide 53: Clinical Monitoring (2)

Monthly visits should include a brief physical exam and a review of

• Rationale for treatment
• Adherence with therapy
• Symptoms of adverse drug reactions
• Plans to continue treatment

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Slide 54:  Clinical Monitoring (3)

• Incidence of hepatitis in persons taking INH is lower than previously thought (0.1 to 0.15%)
• Hepatitis risk increases with age
  • Uncommon in persons < 20 years old
  • Nearly 2% in persons 50 to 64 years old
• Risk increased with underlying liver disease or heavy alcohol consumption

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Slide 55: Laboratory Monitoring (1)

Baseline liver function tests (e.g., AST, ALT, and bilirubin) are not necessary except for patients with the following risk factors:

• HIV infection
• History of liver disease
• Alcoholism
• Pregnancy or in early postpartum period

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Slide 56: Laboratory Monitoring (2)

Repeat laboratory monitoring if patient has

• Abnormal baseline results
• Current or recent pregnancy
• High risk for adverse reactions
• Symptoms of adverse reaction
• Liver enlargement or tenderness during examination

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Slide 57: Laboratory Monitoring (3)

• Asymptomatic elevation of hepatic enzymes seen in 10%-20% of people taking INH
  • Levels usually return to normal after completion of treatment
• Some experts recommend withholding INH if transaminase level exceeds 3 times the upper limit of normal if patient has symptoms of hepatotoxicity, and 5 times the upper limit of normal if patient is asymptomatic⁷

⁷ MMWR June 9, 2000; 49(No. RR-6): 39

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Slide 58: Meeting the Challenge of TB Prevention

For every patient

• Assess TB risk factors
• If risk is present, perform TST or QFT
• If TST or QFT is positive, rule out active TB disease
• If active TB disease is ruled out, initiate treatment for LTBI
• If treatment is initiated, ensure completion

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Slide 59: Additional Resources

For additional information on TB, visit the CDC Division of Tuberculosis Elimination Website at www.cdc.gov/tb

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Slide 60: Guidelines Available Online

• CDC’s Morbidity and Mortality Weekly Report
• American Thoracic Society

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Slide 61: Case Studies

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Slide 62: Case Study A (1)

Patient history

• 29-year-old African-American female
• History of diabetes
• 35 weeks pregnant
• TST = 20 mm of induration
• No symptoms of TB disease
• CXR, CBC, LFTs normal
• No known contact with TB patient

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Slide 63: Case Study A (2)

Questions

1. What are this patient’s risk factors for TB infection or disease?
2. What is the appropriate management for this patient?

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Slide 64: Case Study A (3)

Discussion of risk factors

• Persons with diabetes mellitus are 2 to 4 times more likely to develop TB disease than those without diabetes
• Risk may be higher in insulin-dependent diabetics and those with poorly controlled diabetes

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Slide 65: Case Study A (4)

Discussion of management

• Pregnancy has minimal influence on the pathogenesis of TB or the likelihood of LTBI progressing to disease
• Pregnant women should be targeted for TB testing only if they have specific risk factors for LTBI or progression to disease

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Slide 66: Case Study A (5)

Discussion of management

• Some experts prefer to delay treatment until after the early postpartum period, unless the person has recent TB infection or HIV infection

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Slide 67: Case Study B (1)

Patient history

• 47-year-old Hispanic male
• Moved to U.S. from Bolivia 4 years ago
• Known contact of infectious TB case
• TST = 5 mm of induration
• 3 months later TST = 23 mm of induration
• No symptoms of TB disease
• Normal CXR, CBC, AST, and bilirubin

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Slide 68: Case Study B (2)

 Questions

1. What are the patient’s risk factors for TB infection or disease?
2. Has the management of this patient to date been appropriate?

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Slide 69: Case Study B (3)

Discussion of risk factors

• Patient is a contact of an infectious TB case
• Recent immigrant to the U.S. from a country with a high prevalence of TB

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Slide 70: Case Study B (4)

Discussion of risk factors

• If the patient had not been a contact, the recency of his immigration (less than 4 years) would have made him a candidate for TB testing, but the 5-mm reaction would not be considered positive
• Persons who immigrate from TB-endemic countries have increased rates of TB

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Slide 71: Case Study B (5)

Discussion of risk factors

• Rates of TB approach those of their countries of origin for 5 years after arrival in the U.S.
• These increased rates most likely result from recent M. tuberculosis infection in their native country

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Slide 72: Case Study B (6)

Discussion of management

• Should be treated for LTBI if TST reactions > 10 mm of induration
• As a contact of an active TB case, 5 mm of induration is considered positive
• This patient should have been treated for LTBI immediately after the first TST

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Slide 73: Case Study C (1)

Patient history

• 36-year-old Asian female
• Moved to U.S. from Philippines > 15 years ago
• Plans to work in a correctional facility
• TST result negative 1 year ago
• TST for pre-employment physical = 26 mm of induration
• CXR normal
• No symptoms of TB disease
• No known contact with a TB patient

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Slide74: Case Study C (2)

Questions

1. What are the patient’s risk factors for TB infection or disease?
2. What is the appropriate management for this patient?

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Slide 75: Case Study C (3)

Discussion of risk factors

• Patient’s TST converted from negative to positive (within a 2-year period)
• TST conversion increases risk for progressing from LTBI to TB disease
• Foreign-born status is less of a risk factor, i.e., she immigrated more than 5 years ago

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Slide 76: Case Study C (4)

Discussion of management

• Patient’s TST conversion indicates failure to identify this person as high risk for recent exposure to TB
• Patient may have had extended travel to her country of origin or other high-prevalence parts of the world

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Slide 77: Case Study C (5)

Discussion of management

• Patient is a recent converter and, as such, is a candidate for treatment of LTBI with INH

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Last Reviewed: 05/18/2008
Content Source: Division of Tuberculosis Elimination
National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention

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