Tuberculosis

Key Points

  • Although the risk of transmission of tuberculosis in dental settings is low, the Centers for Disease Control and Prevention (CDC) recommends dental health care personnel include protocols for tuberculosis infection control in their offices’ written infection control program.
  • Infection occurs through inhalation of small airborne droplets containing Mycobacterium tuberculosis, which then travel to the alveoli of the lungs; only people with active disease can spread the infection.
  • A person with latent tuberculosis is not infectious; he or she can be treated in the dental office under standard infection control precautions.
  • However, for a person with active tuberculosis, standard precautions are insufficient to prevent transmission of the bacterium.
Introduction

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 7,163 cases of tuberculosis (a rate of 2.2 cases per 100,000 persons) were reported in the U.S. in 2020.7

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

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.

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 These small particles (1 to 5 micrometers in diameter) can stay suspended in the air for hours.14 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.15 According to one study, up to 77% of respiratory bio-aerosol samples from newly diagnosed patients may contain M. tuberculosis organisms.16

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.17 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).18

Only a person with active tuberculosis can transmit the disease. 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

Infection Control/Precautions

In 2005, the CDC developed guidelines for preventing transmission of M. tuberculosis in health-care settings.11, 18 All dental settings need to follow a tuberculosis infection control program based on three levels of controls (Table).18 The most important component of this program is the use of administrative measures to reduce the risk of exposure to potentially infectious persons.18 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.19 

Table.  Tuberculosis (TB) Precautions for Outpatient Dental Settings 18

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

Dental Patient Management

When taking 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. 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, 20  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, 18 Standard precautions are insufficient to prevent transmission of the bacterium.21 Elective dental treatment should be deferred until the patient has been declared noninfectious by a physician.11, 18 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.18 OSHA describes a standard for respiratory protection, which may be consulted if setting up such a program (CFR 1910.134 Respiratory Protection).22 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.

Dental Healthcare Workers and Skin Testing

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.23 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.24

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.

Dental Office Risk Assessment and Training

The CDC recommends that dental offices perform an annual tuberculosis risk assessment which involves11, 18:

  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 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.25

References
  1. Fukunaga R, Glaziou P, Harris JB, et al. Epidemiology of tuberculosis and progress toward meeting global targets - worldwide, 2019. MMWR Morb Mortal Wkly Rep 2021;70(12):427-30.
  2. Centers for Disease Control and Prevention. Tuberculosis (TB): Data and statistics. "http://www.cdc.gov/tb/statistics/default.htm". Accessed August 30, 2021.
  3. World Health Organization. Global tuberculosis report 2020. "https://apps.who.int/iris/bitstream/handle/10665/336069/9789240013131-eng.pdf". Accessed August 30, 2021.
  4. Houben RM, Dodd PJ. The global burden of latent tuberculosis infection: A re-estimation using mathematical modelling. PLoS Med 2016;13(10):e1002152.
  5. Raviglione M, Sulis G. Tuberculosis 2015: Burden, challenges and strategy for control and elimination. Infect Dis Rep 2016;8(2):6570.
  6. Sulis G, Centis R, Sotgiu G, et al. Recent developments in the diagnosis and management of tuberculosis. NPJ Prim Care Respir Med 2016;26:16078.
  7. Deutsch-Feldman M, Pratt RH, Price SF, Tsang CA, Self JL. Tuberculosis - United States, 2020. MMWR Morb Mortal Wkly Rep 2021;70(12):409-14.
  8. Cleveland JL, Gooch BF, Bolyard EA, et al. TB infection control recommendations from the CDC, 1994: Considerations for dentistry. United States Centers for Disease Control and Prevention. J Am Dent Assoc 1995;126(5):593-9.
  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.
  10. Zemouri C, Awad SF, Volgenant CMC, et al. Modeling of the transmission of coronaviruses, measles virus, influenza virus, Mycobacterium tuberculosis, and Legionella pneumophila in dental clinics. J Dent Res 2020;99(10):1192-98.
  11. Cleveland JL, Robison VA, Panlilio AL. Tuberculosis epidemiology, diagnosis and infection control recommendations for dental settings: An update on the Centers for Disease Control and Prevention guidelines. J Am Dent Assoc 2009;140(9):1092-9.
  12. Sosa LE, Njie GJ, Lobato MN, et al. Tuberculosis screening, testing, and treatment of U.S. health care personnel: Recommendations from the National Tuberculosis Controllers Association and CDC, 2019. MMWR Morb Mortal Wkly Rep 2019;68(19):439-43.
  13. Issarow CM, Mulder N, Wood R. Modelling the risk of airborne infectious disease using exhaled air. J Theor Biol 2015;372:100-6.
  14. Wells WF. Aerodynamics of droplet nuclei. In: Wells WF, editor. Airborne contagion and air hygiene: An ecological study of droplet infections. Cambridge, MA: Harvard University Press; 1955. p. 13-19.
  15. Patterson B, Wood R. Is cough really necessary for TB transmission? Tuberculosis 2019;117:31-35.
  16. Patterson B, Morrow C, Singh V, et al. Detection of Mycobacterium tuberculosis bacilli in bio-aerosols from untreated TB patients. Gates Open Res 2017;1:11.
  17. Deutsch-Feldman M, Pratt RH, Price SF, Tsang CA, Self JL Tuberculosis: United States, 2020. MMWR Morb Mortal Wkly Rep 2021;70:409–414. "https://www.cdc.gov/mmwr/volumes/70/wr/mm7012a1.htm". Accessed August 30, 2021.
  18. Jensen PA, Lambert LA, Iademarco MF, Ridzon R. Guidelines for preventing the transmission of Mycobacterium tuberculosis in health-care settings, 2005. MMWR Recomm Rep.  2005 Dec 30;54(RR-17):1-141. "https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5417a1.htm". Accessed August 30, 2021.
  19. Hopewell PC, Reichman LB, Castro KG. Parallels and mutual lessons in tuberculosis and COVID-19 transmission, prevention, and control. Emerg Infect Dis 2021;27(3):681-86.
  20. Kakisi OK, Kechagia AS, Kakisis IK, Rafailidis PI, Falagas ME. Tuberculosis of the oral cavity: A systematic review. Eur J Oral Sci 2010;118(2):103-9.
  21. Centers for Disease Control and Prevention Guidelines for infection control in dental health-care settings — 2003 (December 19, 2003 / vol. 52 / no. Rr-17). U.S. Department of Health and Human Services 2003. "http://www.cdc.gov/mmwr/PDF/rr/rr5217.pdf". Accessed September 6, 2021.
  22. Occupational Safety & Health Administration. Respiratory Protection (1910.134). U.S. Department of Labor. "https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_id=12716&p_table=STANDARDS". Accessed August 26, 2021.
  23. Advisory Council for the Elimination of Tuberculosis (ACET). The role of BCG vaccine in the prevention and control of tuberculosis in the United States--a joint statement by the Advisory Council for the Elimination of Tuberculosis and the Advisory Committee on Immunization Practices. Centers for Disease Control and Prevention. September 1995. "http://www.cdc.gov/Mmwr/preview/mmwrhtml/00041047.htm". Accessed August 27, 2021.
  24. 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.
  25. Centers for Disease Control and Prevention. Tuberculosis (TB): Infection control in health care settings. U.S. Department of Health and Human Services. "http://www.cdc.gov/tb/". Accessed September 6, 2021.
Last Updated: September 7, 2021

Prepared by:

Department of Scientific Information, Evidence Synthesis & Translation Research, ADA Science & Research Institute, LLC.


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