Tuberculosis

Tuberculosis is a leading infectious cause of morbidity and mortality at a global level, accounting for approximately 10.0 million new cases and 1.4 million deaths in 2019.¹ Approximately 25 percent of the world’s population is infected with tuberculosis.^2-4 Co-infection with human immunodeficiency virus (HIV) is one of the strongest risk factors for tuberculosis infection, and tuberculosis is the leading cause of death among people living with HIV infection.^{5, 6}

In 2019, the largest number of new tuberculosis cases occurred in Southeast Asia and Africa, followed by the Western Pacific region. Eight countries accounted for two-thirds of the new tuberculosis cases that year: India, Indonesia, China, the Philippines, Pakistan, Nigeria, Bangladesh and South Africa.¹ A total of 8,300 cases of tuberculosis (a rate of 2.5 cases per 100,000 persons) were reported in the U.S. in 2022.⁷

Although the risk of transmission of tuberculosis in dental settings is low,^8-10 the Centers for Disease Control and Prevention (CDC) recommends dental health care personnel (DHCP) include protocols for tuberculosis infection control in their offices’ written infection control program.^{11, 12}

Tuberculosis is caused by infection with Mycobacterium tuberculosis (M. tuberculosis).¹¹ Infection occurs through inhalation of airborne droplets containing viable M. tuberculosis, which then travel to the alveoli of the lungs. Only people with active disease can spread the infection.¹³

M. tuberculosis is transmitted through infectious airborne particles, known as “droplet nuclei,” which can be generated when people with pulmonary or laryngeal tuberculosis sneeze, cough, speak or sing.^{11, 13, 14} These small particles (1 to 5 micrometers in diameter) can stay suspended in the air for hours.¹⁵ Non-coughing individuals who are suspected of having tuberculosis cannot be presumed to be non-infectious because M. tuberculosis transmission may still occur without the presence of coughing.¹⁶ According to one study, up to 77% of respiratory bio-aerosol samples from newly diagnosed patients may contain M. tuberculosis organisms.¹⁷

If a susceptible person inhales aerosolized droplet nuclei containing M. tuberculosis, infection may begin if the organisms reach the alveoli. Within two to 12 weeks, the body’s immunological response to M. tuberculosis usually prevents further multiplication and spread.¹¹ The mycobacterium can live in the lungs of an infected person for years, even a lifetime, without the person exhibiting any symptoms; this state is called latent infection.¹¹ A person with latent tuberculosis is generally asymptomatic and not infectious to others but the infection can develop into active tuberculosis in the future and usually exhibits a positive reactive tuberculin skin test.¹¹

Most people who have latent tuberculosis infection never develop active disease, but if they do not receive treatment for latent infection, about 10 percent of people with latent infections can develop active disease over a lifetime.¹⁸ This can happen when the person’s immune system is weakened, allowing the mycobacteria to cause active tuberculosis infection (e.g., individuals with HIV, diabetes, certain hematologic disorders such as leukemias and lymphomas, prolonged corticosteroid use, and other conditions).¹⁹

Only a person with active tuberculosis can transmit the disease.¹³ People with active tuberculosis infection generally have symptoms (e.g., persistent, productive cough; night sweats, fever, weakness or fatigue; weight loss; pain in the chest); and can have a positive tuberculin skin test reaction.¹¹

In 2005, the CDC developed guidelines for preventing transmission of M. tuberculosis in health-care settings.^{11, 19} All dental settings need to follow a tuberculosis infection control program based on three levels of controls (Table).¹⁹ The most important component of this program is the use of administrative measures to reduce the risk of exposure to potentially infectious persons.¹⁹ Environmental controls reduce the spread and concentration of infectious droplet nuclei in the ambient air. Finally, use respiratory protection and respiratory hygiene to reduce the risk of exposure to infectious droplet nuclei that may be expelled into the air. Several of these tuberculosis-specific infection control recommendations are also applicable to preventing transmission of other airborne etiologic agents, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which, like M. tuberculosis, is transmitted through secretions of the respiratory tract.²⁰

Table.  Tuberculosis (TB) Precautions for Outpatient Dental Settings ¹⁹

Administrative Controls

• Assign responsibility for managing TB infection control program
• Conduct annual risk assessment
• Develop and implement a written TB infection control plan for promptly identifying and isolating patients with suspected or confirmed TB disease for medical evaluation or urgent dental treatment
• Instruct patients to cover mouth when coughing and wear a surgical mask
• Educate dental health care personnel (DHCP) regarding signs and symptoms of TB
• When hiring DHCP, screen for latent TB infection and TB disease
• Postpone non-urgent dental treatment (patients requiring urgent care should be promptly referred to an appropriate medical setting for evaluation of possible infectiousness)

Environmental Controls

• Use an airborne infection isolation room to provide urgent dental treatment to patients with suspected or confirmed infectious TB
• In settings with high volume of patients with suspected or confirmed TB, use high-efficiency particulate air filters or ultraviolet germicidal irradiation

Respiratory Protection Controls

• Use respiratory precautions—at least an N95 particulate filtering facepiece respirator (disposable)—for DHCP when they are providing urgent dental treatment to patients with suspected or confirmed TB
• Instruct TB patients to cover mouth when coughing and to wear a surgical mask

When taking a medical history, it can help manage risk to ask all patients about past history of or exposure to tuberculosis and about signs and symptoms of tuberculosis and medical conditions that increase risk for disease.¹³ Respiratory tuberculosis may be present in any patient with symptoms including coughing for more than three weeks, loss of appetite, unexplained weight loss, night sweats, bloody sputum or hemoptysis, hoarseness, chest pains, fever, fatigue or presence of persistent lesions of the oral mucosa that are non-responsive to therapy.^{11, 21}  A person with non-infectious latent tuberculosis may be treated in the dental office under standard infection control precautions.

Any patient with symptoms suggestive of active tuberculosis disease should be removed from the area of other patients or staff, instructed to wear a surgical or procedure mask, assessed for the urgency of their dental care and promptly referred for medical care.^{11, 19} Standard precautions are insufficient to prevent transmission of the bacterium.²² Elective dental treatment should be deferred until the patient has been declared noninfectious by a physician.^{11, 19} Urgent dental care for a person with suspected or active tuberculosis should be provided in a facility that has the capacity for airborne infection isolation and has a respiratory protection program in place.¹⁹ OSHA describes a standard for respiratory protection, which may be consulted if setting up such a program (CFR 1910.134 Respiratory Protection).²³ Standard surgical face masks are not adequate to protect against tuberculosis transmission; however, appropriate respiratory protection (e.g., fitted, disposable N95 respirators) provide protection when treating a patient with active disease.

The CDC’s Advisory Committee on Immunization Practices does not recommend routine immunization (Bacille Calmette-Guérin [BCG]) of U.S. health-care workers against tuberculosis.²⁴ However, the CDC does recommend that all persons in the dental office who have the potential for exposure to M. tuberculosis through air space shared with persons with infectious tuberculosis disease (which essentially means all personnel) be tested for infection, either by whole-blood interferon gamma release assay, or a two-step baseline tuberculin skin test at the beginning of employment, as well having an individual tuberculosis risk assessment. Serial tuberculosis screening and testing are no longer routinely recommended though can be considered for those working in medium-risk settings and settings with potential for ongoing transmission. Health care personnel are also advised to receive annual tuberculosis education, which is to include information on risk factors, signs and symptoms of tuberculosis disease, tuberculosis infection control policies and procedures, and treatment regimen options for latent tuberculosis infection.²⁵

Individuals with a positive test should consult with their physician to determine whether any treatment is required. The CDC encourages treatment for all health-care workers with untreated latent TB infection unless medically contraindicated.¹²

The CDC and National Tuberculosis Controllers Association recommend that, following a recognized exposure, health-care workers with no prior TB disease or latent TB infection who had a negative baseline TB test, have an interferon gamma release assay or tuberculin skin test. They go on to recommend that if the test is negative, it should be repeated 8-10 weeks after exposure.¹²

Individuals with a positive test should consult with their physician to determine whether any treatment is required.

The CDC recommends that dental offices perform an annual tuberculosis risk assessment which involves^{11, 19}:

1. Risk Classification—identifying the number of cases of active tuberculosis encountered in the office. The CDC classifies a low-risk setting as one where fewer than three patients with active tuberculosis are seen each year. An office that saw three or more patients with active tuberculosis in the past year is classified as a medium-risk setting. An office where there is evidence of a transmission of tuberculosis within the past year or one of the staff has a confirmed diagnosis of active tuberculosis is temporarily classified as potential ongoing transmission.
2. Community Awareness—being aware of the tuberculosis risk level in the surrounding community. Contact the local or state health department to find out the number of tuberculosis cases in the community.

Just because a dentist practices in a community with a high number of tuberculosis cases does not mean that dentist’s office is at medium or high risk. It is the likelihood of encountering tuberculosis cases in that particular practice which determines its risk category.

The level of risk for a dental office helps determine the types of administrative, environmental, and respiratory protection controls needed. Annual risk reassessment helps serve as an ongoing evaluation of the quality of the office’s tuberculosis infection control practices and helps identify any needed improvements in infection control measures.

The CDC recommends that dental office personnel receive training and education on M. tuberculosis and tuberculosis disease that emphasizes risks posed by an undiagnosed person with tuberculosis disease in a dental-care setting and the specific measures to reduce this risk. Training and education materials are available from the CDC.²⁶

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9. Petti S. Tuberculosis: Occupational risk among dental healthcare workers and risk for infection among dental patients. A meta-narrative review. J Dent 2016;49:1-8.
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25. Thanassi W, Behrman AJ, Reves R, et al. Tuberculosis screening, testing, and treatment of US health care personnel: ACOEM and NTCA Joint Task Force on Implementation of the 2019 MMWR Recommendations. J Occup Environ Med 2020;62(7):e355-e69.
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• Related ADA Oral Health Topic:  Infection Control and Sterilization
• Search JADA for related articles
• ADA Library Resources

• Division of Tuberculosis Elimination (DTBE): Find TB Resources
• Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Settings, 2005
• Tuberculosis Screening, Testing, and Treatment of U.S. Health Care Personnel (2019)
• TB Programs
• Tuberculosis (TB)