Tuberculosis, Latent (LTBI)

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Basics

Description

  • Latent tuberculosis infection (LTBI) is an asymptomatic, noninfectious condition following exposure to an active case of tuberculosis (TB). LTBI is usually detected by a screening skin or blood test.
  • Active TB occurs in 5–10% of infected individuals who have not received preventive therapy. Chance of active TB increases with immunosuppression and is highest for all individuals within 2 years of infection; 85% of the cases are pulmonary, which can be spread person-to-person via aerosol route.
  • Greater than 80% of active TB cases in United States result from untreated LTBI (1).
  • LTBI treatment is a key component of the TB elimination strategy for the United States.
ALERT
  • Nitrosamine particles have been isolated in rifampin and rifapentine products in 2020. These nitrosamine particles are potential or probable carcinogens, and due to the life-threatening nature of TB, the FDA has approved ongoing production of these antimicrobials with close monitoring (2).
  • The current pace of decline in TB incidence will not eliminate TB in the United States in the 21st century. Extra effort is needed to identify patients with LTBI (3).

Epidemiology

  • In the United States, high-risk groups include immigrants from countries with a high TB rate (countries other than the United States, Canada, Australia, New Zealand, or a country in western or northern Europe); persons with a history of drug use or experiencing homelessness; HIV-infected or immunocompromised individuals; and persons living or working in high-risk congregate settings such as nursing homes, carceral facilities, and health care workers (3).
  • TB is a major cause of death in individuals infected with HIV (3).
  • Newly exposed (particularly children) are also at high risk.
  • In 2018, there were 9,029 new TB cases reported in the United States, a 0.7% decrease from 2017 (1).
  • Among the 9,029 TB cases reported in the United States in 2018, approximately 2/3 (6,276 [69.5%]) occurred in non–U.S.-born persons, whereas 2,662 (29.5%) occurred in U.S.-born persons; 91 (1.0%) cases occurred in persons for whom no national origin was documented (1).
  • Among non–U.S.-born persons with TB, incidence in 2018 was highest among Asians, followed by Native Hawaiians/Pacific Islanders, non-Hispanic blacks (blacks), Hispanics, and American Indian/Alaska Natives, and was lowest among non-Hispanic whites (whites) (1),(3).
  • The highest TB incidence for U.S.-born persons occurred among Native Hawaiians/Pacific Islanders, followed by American Indians/Alaska Natives, blacks, Asians, and Hispanics, and was lowest in whites (1).

Incidence
In 2018, a total of 9,029 new TB cases were reported in the United States (1).

Prevalence
  • 13 million people in the United States are infected with TB (1).
  • ~1/4 of the world’s population harbors latent TB.

Etiology and Pathophysiology

Mycobacterium tuberculosis, Mycobacterium bovis, and Mycobacterium africanum

Risk Factors

  • Immigrants from TB-endemic countries, which include most countries of Africa, Asia, and Eastern Europe
  • Close contact with infected individual
  • Living or working in a congregate setting (e.g., prison, nursing home)
  • Use of illicit drugs
  • Lower socioeconomic status or experiencing homelessness
  • Health care workers
  • Laboratory personnel working with mycobacteria

General Prevention

  • Screen for LTBI and treat individuals with positive tests.
  • If a person has fibrotic lung changes on imaging and no evidence of TB treatment, these patients should be screened for LTBI, regardless of their other risk factors.
  • Special population: Organ donors should be screened. If donor is deceased, interferon-γ release assay (IGRA) testing is still possible.

Commonly Associated Conditions

  • HIV infection (see “Initial Tests (lab, imaging)”)
  • Immunosuppression
  • IV drug use and substance use disorders

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Basics

Description

  • Latent tuberculosis infection (LTBI) is an asymptomatic, noninfectious condition following exposure to an active case of tuberculosis (TB). LTBI is usually detected by a screening skin or blood test.
  • Active TB occurs in 5–10% of infected individuals who have not received preventive therapy. Chance of active TB increases with immunosuppression and is highest for all individuals within 2 years of infection; 85% of the cases are pulmonary, which can be spread person-to-person via aerosol route.
  • Greater than 80% of active TB cases in United States result from untreated LTBI (1).
  • LTBI treatment is a key component of the TB elimination strategy for the United States.
ALERT
  • Nitrosamine particles have been isolated in rifampin and rifapentine products in 2020. These nitrosamine particles are potential or probable carcinogens, and due to the life-threatening nature of TB, the FDA has approved ongoing production of these antimicrobials with close monitoring (2).
  • The current pace of decline in TB incidence will not eliminate TB in the United States in the 21st century. Extra effort is needed to identify patients with LTBI (3).

Epidemiology

  • In the United States, high-risk groups include immigrants from countries with a high TB rate (countries other than the United States, Canada, Australia, New Zealand, or a country in western or northern Europe); persons with a history of drug use or experiencing homelessness; HIV-infected or immunocompromised individuals; and persons living or working in high-risk congregate settings such as nursing homes, carceral facilities, and health care workers (3).
  • TB is a major cause of death in individuals infected with HIV (3).
  • Newly exposed (particularly children) are also at high risk.
  • In 2018, there were 9,029 new TB cases reported in the United States, a 0.7% decrease from 2017 (1).
  • Among the 9,029 TB cases reported in the United States in 2018, approximately 2/3 (6,276 [69.5%]) occurred in non–U.S.-born persons, whereas 2,662 (29.5%) occurred in U.S.-born persons; 91 (1.0%) cases occurred in persons for whom no national origin was documented (1).
  • Among non–U.S.-born persons with TB, incidence in 2018 was highest among Asians, followed by Native Hawaiians/Pacific Islanders, non-Hispanic blacks (blacks), Hispanics, and American Indian/Alaska Natives, and was lowest among non-Hispanic whites (whites) (1),(3).
  • The highest TB incidence for U.S.-born persons occurred among Native Hawaiians/Pacific Islanders, followed by American Indians/Alaska Natives, blacks, Asians, and Hispanics, and was lowest in whites (1).

Incidence
In 2018, a total of 9,029 new TB cases were reported in the United States (1).

Prevalence
  • 13 million people in the United States are infected with TB (1).
  • ~1/4 of the world’s population harbors latent TB.

Etiology and Pathophysiology

Mycobacterium tuberculosis, Mycobacterium bovis, and Mycobacterium africanum

Risk Factors

  • Immigrants from TB-endemic countries, which include most countries of Africa, Asia, and Eastern Europe
  • Close contact with infected individual
  • Living or working in a congregate setting (e.g., prison, nursing home)
  • Use of illicit drugs
  • Lower socioeconomic status or experiencing homelessness
  • Health care workers
  • Laboratory personnel working with mycobacteria

General Prevention

  • Screen for LTBI and treat individuals with positive tests.
  • If a person has fibrotic lung changes on imaging and no evidence of TB treatment, these patients should be screened for LTBI, regardless of their other risk factors.
  • Special population: Organ donors should be screened. If donor is deceased, interferon-γ release assay (IGRA) testing is still possible.

Commonly Associated Conditions

  • HIV infection (see “Initial Tests (lab, imaging)”)
  • Immunosuppression
  • IV drug use and substance use disorders

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