Deciding When to Treat Latent TB Infection

People with latent TB infection do not have symptoms, and they cannot spread TB bacteria to others. However, if latent TB bacteria become active in the body and multiply, the person will go from having latent TB infection to being sick with TB disease. For this reason, people with latent TB infection should be treated to prevent them from developing TB disease.

Treatment of latent TB infection is essential to controlling TB in the United States because it substantially reduces the risk that latent TB infection will progress to TB disease. In the United States, up to 13 million people may have latent TB infection. Without treatment, on average 1 in 10 people with latent TB infection will get sick with TB disease in the future. The risk is higher for people with HIV, diabetes, or other conditions that affect the immune system. More than 80% of people who get sick with TB disease in the United States each year get sick from untreated latent TB infection.

Treatment of latent TB infection should start after excluding the possibility of TB disease.

Groups Who Should be Given High Priority for Latent TB Infection Treatment include:

• People with a positive TB blood test (interferon-gamma release assay or IGRA).

• People with a tuberculin skin test (TST) reaction of 5 or more millimeters who are:
  • HIV-infected persons.
  • Recent contacts to a patient with active TB disease.
  • Persons with fibrotic changes on chest radiograph consistent with old TB.
  • Organ transplant recipients.
  • Persons who are immunosuppressed for other reasons (e.g., taking the equivalent of  ≥15 mg/day of prednisone for 1 month or longer, taking TNF-α antagonists).

• People with a TST reaction of 10 or more millimeters who are:
  • From countries where TB is common, including Mexico, the Philippines, Vietnam, India, China, Haiti, and Guatemala, or other countries with high rates of TB. (Of note, people born in Canada, Australia, New Zealand, or Western and Northern European countries are not considered at high risk for TB infection, unless they spent time in a country with a high rate of TB.)
  • Injection drug users.
  • Residents and employees of high-risk congregate settings (e.g., correctional facilities, nursing homes, homeless shelters, hospitals, and other health care facilities).
  • Mycobacteriology laboratory personnel.
  • Children under 4 years of age, or children and adolescents exposed to adults in high-risk categories.

Persons with no known risk factors for TB may be considered for treatment of LTBI if they have either a positive IGRA result or if their reaction to the TST is 15 mm or larger. However, targeted TB testing programs should only be conducted among high-risk groups. All testing activities should be accompanied by a plan for follow-up care for persons with latent TB infection or disease.

As of 2018, there are four CDC-recommended treatment regimens for latent TB infection that use isoniazid (INH), rifapentine (RPT), and/or rifampin (RIF). All the regimens are effective. Healthcare providers should prescribe the more convenient shorter regimens, when possible. Patients are more likely to complete shorter treatment regimens. Treatment must be modified if the patient is a contact of an individual with drug-resistant TB disease. Consultation with a TB expert is advised if the known source of TB infection has drug-resistant TB.