Oral Health Topics
Tuberculosis (TB) is caused by infection with the bacterium Mycobacterium tuberculosis. Infection occurs through inhalation of the bacterium, which then travels to the alveoli of the lungs. In most people who become infected, the body is able to contain the bacteria and prevent it from multiplying. The bacterium 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 TB infection. A person with latent TB is not infectious to others but the infection can develop into active TB disease in the future and usually exhibits a positive reactive tuberculin skin test.
People with latent TB infection
- have no symptoms
- don’t feel sick
- can’t spread TB to others
- can have a positive tuberculin skin test reaction
- can develop TB disease later in life if they do not receive treatment for latent TB infection.
Most people who have latent TB infection never develop active TB, but if they do not receive treatment for latent TB infection about 10 percent of latent TB infections can develop active disease over a lifetime.
This can happen when the person’s immune system is weakened allowing the bacteria to become active and cause TB disease (e.g., individuals with HIV, diabetes, certain hematologic disorders such as leukemias and lymphomas, prolonged corticosteroid use, and other conditions). Only a person with active TB can transmit the disease.
People with active TB disease
- have symptoms (e.g., a productive cough, night sweats, fever, weakness or fatigue, weight loss, pain in the chest);
- feel sick;
- can spread TB to others; and
- can have a positive tuberculin skin test reaction.
The Centers for Disease Control and Prevention (CDC) has developed guidelines for preventing transmission of Mycobacterium tuberculosis in health-care settings.1
Routine Medical History
Ask all patients about past history of TB or exposure to TB. Ask about TB signs and symptoms and medical conditions that increase their risk for TB disease when taking their medical history. A diagnosis of respiratory TB should be considered for 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. The ADA’s Health History Form contains these kinds of questions.
Dental Treatment and TB
Because a person with latent TB is not infectious, he or she can be treated in the dental office under standard infection control precautions.2
Any patient with symptoms suggestive of active TB 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. Standard precautions are insufficient to prevent transmission of the bacterium. Elective dental treatment should be deferred until the patient has been declared non-infectious by a physician. Urgent dental care for a person with suspected or active TB 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 a program (CFR 1910.134 Respiratory Protection). When treating a patient with active TB, dental health care personnel should use respiratory protection (e.g., fitted, disposable N-95 respirators). Standard surgical face masks are not designed to protect against TB transmission.
The CDC recommends that dental offices perform an annual risk assessment. Risk assessment involves:
- Risk Classification—identifying the number of cases of active TB encountered in the office. The CDC classifies a low-risk setting as one where less than 3 patients with active TB are seen each year. An office that saw more than or equal to 3 patients with active TB in the past year is classified as a medium-risk setting. An office where there is evidence of a transmission of TB within the past year or one of the staff has a confirmed diagnosis of active TB is temporarily classified as potential ongoing transmission
- Community Awareness—being aware of the TB risk level in the surrounding community. Contact the local or state health department to find out the number of TB cases in the community.
Just because a dentist practices in a community with a high number of TB cases does not mean that that dentist’s office is medium risk. The likelihood of encountering TB cases in that particular practice determines its risk category.
The level of risk for encountering active TB in the dental office determines the types of administrative, environmental, and respiratory protection controls needed. Annual risk reassessment can also serve as an ongoing evaluation tool of the quality of the office’s TB infection control practices and allows identification of any needed improvements in infection control measures.
The CDC recommends that dental office personnel receive training and education on M. tuberculosis and TB disease that emphasizes the increased risks posed by an undiagnosed person with TB disease in a dental-care setting and the specific measures to reduce this risk. Training and education materials are available from the CDC
(http://www.cdc.gov/tb and http://www.findtbresources.org).
Dental Healthcare Workers and TB Skin Test
The CDC’s Advisory Committee on Immunization Practices does not recommend routine immunization (Bacille-Calmette- Guérin [BCG]) of U.S. health care workers against TB. 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 TB disease (which essentially means all personnel) receive a two-step baseline tuberculin skin test (TST) 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. By doing so, TST conversions (from a negative to positive result) following an exposure incident can be distinguished from positive TST 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.
- Centers for Disease Control and Prevention:
Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Settings, 2005. MMWR 2005; 54(RR17);1-141
- Centers for Disease Control and Prevention:
Guidelines for Infection Control in Dental Health-Care Settings—2003; 52(RR17);1-61