Is Tuberculosis (TB) Contagious?

  • Medical Author:
    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

What is tuberculosis (TB)?

Tuberculosis (TB) is a disease (bacterial infection) caused by a bacterium named Mycobacterium tuberculosis that usually infects the lungs, but in some individuals, the bacteria can attack any part of the body. Before treatments were effective against TB, it was the leading cause of death in the United States.

Is tuberculosis (TB) contagious?

Yes, TB is highly contagious and can be transmitted from an infected person to an uninfected person, mainly when a person with TB coughs, sneezes, speaks, or even sings (known as airborne transmission or airborne disease). Other people who breathe in the aerosolized bacteria can become infected. Some individuals have TB infections but show no symptoms because their bodies prevent TB organisms from growing. Patients with this type of infection are termed as having latent (dormant) TB. Individuals with latent TB have the organisms suppressed; in this condition, the individuals are not contagious for TB when the organisms are dormant. However, if a person with latent TB is no longer able to suppress the TB organisms, that individual can then become contagious.

Mycobacterium tuberculosis organisms can survive for a while even in the deceased; to avoid getting TB, physicians who perform autopsies have to be careful not to spread the organisms into the air while they're doing their investigations.

How will I know if I have tuberculosis?

People may suspect they have tuberculosis if they have spent any length of time around coughing or sneezing individuals known to have tuberculosis. Symptoms and signs of TB include the following:

A physician can order skin tests, TB blood tests, and send sputum samples for specialized stains and culture to definitively diagnose tuberculosis in an individual.

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Tuberculosis (TB) Prevention

A vaccine against TB is commercially available; it is termed BCG, or Bacille Calmette-Guerin vaccine. However, the vaccine is not recommended for use in the U.S. because of the low risk for TB infections.

How do people transmit tuberculosis?

TB spreads when the organisms are coughed up or aerosolized by sneezing, speaking, or singing. The U.S. Centers for Disease Control and Prevention (CDC) states that TB is not spread by handshakes, sharing food, drinks, or toothbrushes, touching items like toilet seats, clothing, or bedsheets, or kissing. People with other health problems like diabetes, HIV infection, drug abuse, alcohol abuse, and/or recent exposure to individuals with TB are at increased risk for contracting TB.

What is the incubation period for tuberculosis?

The incubation period for tuberculosis is measured from exposure time to time of development of a positive tuberculin skin test. In most individuals, the incubation period varies from approximately two to 12 weeks. However, the risk for developing active disease is highest in the first two years after infection and development of a positive TB skin test.

How will I know if I am cured of tuberculosis? What is the contagious period for TB?

Treatment for tuberculosis, both active infections and latent TB infections, involves the use of several different anti-TB medications (for example, isoniazid [Nydrazid, Laniazid, INH], rifampin [Rifadin], rifapentine [Priftin], ethambutol [Myambutol], pyrazinamide), often in combination, for up to a total of six to nine months. A physician will determine the best treatment for you on an individual basis, since some strains of the bacteria are resistant to certain drugs. Some people are probably noncontagious after two weeks while on medication or during treatment but some researchers suggest that others may take longer (months) until they are not able to spread the disease. Reduction or absence of symptoms and signs suggests that a person on antibiotics is unlikely to be contagious, but this is not always true.

When should I contact a medical caregiver about tuberculosis?

Tuberculosis, like many diseases, is best treated early in the infection. Consequently, you should contact a physician if

  • you have been exposed to someone with active TB;
  • you have had a positive TB skin test;
  • you have developed symptoms of a severe cough with blood-tinged or bloody sputum;
  • you have other symptoms of TB, such as fatigue, fever, or night sweats along with coughing;
  • your condition worsens with treatment;
  • you have symptoms of yellowing of the skin and whites of the eyes (jaundice) while undergoing treatment;
  • your vision changes, such as developing blurry or odd colored vision.

An individual should not put off seeing a physician if there's slightest chance he or she has TB because the disease can progress and eventually cause death if not treated in a timely fashion.

REFERENCES:

Herchline, T. "Tuberculosis." Medscape.com. Oct. 22, 2015. <http://emedicine.medscape.com/article/230802-overview>.

United States. Centers for Disease Control and Prevention. "Tuberculosis (TB)." Apr. 28, 2015. <http://www.cdc.gov/tb/>.

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Reviewed on 8/16/2016
References
REFERENCES:

Herchline, T. "Tuberculosis." Medscape.com. Oct. 22, 2015. <http://emedicine.medscape.com/article/230802-overview>.

United States. Centers for Disease Control and Prevention. "Tuberculosis (TB)." Apr. 28, 2015. <http://www.cdc.gov/tb/>.

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