Tuberculosis

Tuberculosis is a leading infectious cause of morbidity and mortality at a global level, accounting for approximately 10.0 million new cases and 1.3 million deaths in 2017.¹ One-fourth of the world’s population is infected with tuberculosis.¹ 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.^{2, 3} In 2017, the largest number of new TB cases occurred in Southeast Asia and the Western Pacific regions, followed by Africa. Eight countries accounted for two thirds of the new TB cases that year: India, China, Indonesia, the Philippines, Pakistan, Nigeria, Bangladesh and South Africa.⁴ Approximately 9,105 cases of tuberculosis (a rate of 2.8 cases per 100,000 persons) were reported in the U.S. in 2017.¹

Although the risk of transmission of tuberculosis in dental settings is low,^{5, 6} 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.⁷

Tuberculosis is caused by infection with Mycobacterium tuberculosis.⁷ Infection occurs through inhalation of mycobacteria, which then travel to the alveoli of the lungs.  Only people with active disease can spread the infection. M. tuberculosis is communicated through airborne particles, known as “droplet nuclei,” which can be generated when people with pulmonary or laryngeal tuberculosis sneeze, cough, speak or sing.⁷ These small particles (1 to 5 micrometers in diameter) can stay suspended in the air for hours.⁸ If a susceptible person inhales 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.⁷ 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.⁷ 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.⁷ 

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.⁷ 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).⁹

Only a person with active tuberculosis can transmit the disease. People with active tuberculosis infection generally have symptoms (e.g., a productive cough, night sweats, fever, weakness or fatigue, weight loss, pain in the chest); and can have a positive tuberculin skin test reaction.⁷

In 2005, the CDC developed guidelines for preventing transmission of M. tuberculosis in health-care settings.^{7, 10} All dental settings need to follow a TB infection control program based on three levels of controls (Table).⁴ The most important component of this program is the use of administrative measures to reduce the risk of exposure to potentially infectious persons.¹⁰ 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.

Table.  Tuberculosis (TB) Precautions for Outpatient Dental Settings ^{7, 10}

Administrative Controls	Assign responsibility for managing TB infection control program Conduct annual risk assessment Develop written TB infection control policies 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/or wear a surgical mask Ensure that dental health care personnel (dental health care personnel (DHCP)) are educated regarding signs and symptoms of TB  When hiring DHCP, ensure that they are screened for latent TB infection and TB disease Postpone urgent dental treatment
Environmental Controls	Use 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 filtering face piece (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

Ask all patients about past history of or exposure to tuberculosis. Ask about signs and symptoms of tuberculosis and medical conditions that increase risk for disease when taking the medical history. A Respiratory tuberculosis should be suspected in any patient with symptoms including coughing for more than 3 weeks, loss of appetite, unexplained weight loss, night sweats, bloody sputum or hemoptysis, hoarseness, fever, fatigue or chest pains.⁷  Because a person with latent tuberculosis is not infectious, he or she can be treated in the dental office under standard infection control precautions.^{11, 12}

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.^{7, 10} Standard precautions are insufficient to prevent transmission of the bacterium. Elective dental treatment should be deferred until the patient has been declared noninfectious by a physician.^{7, 10} 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. OSHA describes a standard for respiratory protection, which should be consulted if setting up such a program (CFR 1910.134 Respiratory Protection).¹³ When treating a patient with active disease, dental health care personnel should use respiratory protection (e.g., fitted, disposable N-95 respirators). Standard surgical face masks are not adequate to protect against tuberculosis transmission.

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.¹⁴ 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 in low-risk settings, every 12 months in medium-risk settings and every 8–10 weeks in the event of potential ongoing transmission until no further evidence of ongoing transmission is apparent.^{7, 10, 15} By doing so, conversions (from a negative to positive result) following an exposure incident can be distinguished from positive results resulting from previous exposures. After baseline testing additional TB screening is not necessary in low-risk settings unless an exposure to M. tuberculosis occurs.

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

The CDC recommends that dental offices perform an annual risk assessment.^{7, 10} Risk assessment involves:

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 3 patients with active tuberculosis are seen each year. An office that saw 3 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 determines the types of administrative, environmental, and respiratory protection controls needed. Annual risk reassessment serves as an ongoing evaluation of the quality of the office’s tuberculosis infection control practices and serves to 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.⁹

1. Centers for Disease Control and Prevention. Tuberculosis (TB): Data and statistics. Accessed March 14, 2019. 
2. Raviglione M, Sulis G. Tuberculosis 2015: Burden, Challenges and Strategy for Control and Elimination. Infect Dis Rep 2016;8(2):6570.
3. 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.
4. World Health Organization. Tuberculosis. Accessed March 14, 2019.
5. 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.
6. Petti S. Tuberculosis: Occupational risk among dental healthcare workers and risk for infection among dental patients. A meta-narrative review. Journal of Dentistry 2016;49(Supplement C):1-8.
7. 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.
8. 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.
9. Centers for Disease Control and Prevention. Tuberculosis (TB). U.S. Department of Health and Human Services. Accessed March 14, 2019.
10. 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. Accessed March 14, 2019.
11. Centers for Disease Control and Prevention. Summary of Infection Prevention Practices in Dental Settings: Basic Expectations for Safe Care. Atlanta, GA: Centers for Disease Control and Prevention 2016. Accessed March 14, 2019.
12. 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. Accessed March 14, 2019.
13. Occupational Safety & Health Administration. Respiratory Protection (1910.134). U.S. Department of Labor. Accessed March 14, 2019.
14. 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. Accessed March 14, 2019.
15. Lewinsohn DM, Leonard MK, LoBue PA, et al. Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention Clinical Practice Guidelines: Diagnosis of Tuberculosis in Adults and Children. Clinical Infectious Diseases 2017;64(2):111-15.

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Centers for Disease Control and Prevention (CDC)

• Division of Tuberculosis Elimination (DTBE): TB Resources
• Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Settings, 2005
• State and Local Tuberculosis Control Programs
• Tuberculosis (TB)