Tell me more about TB.
Tuberculosis is a disease caused by Mycobacterium tuberculosis that primarily attacks the lungs, though any organ in the body can be affected. For 90% of persons infected with TB, the bacteria will be walled off by the immune system and the disease will remain latent in the body, but always with the possibility of multiplying and causing infection. However, when the immune system weakens because of HIV disease, corticosteroid use, autoimmune disease, or other chronic conditions, the TB bacteria are able to multiply freely in the body and cause disease.
While TB was once the second leading cause of death in the US, great steps have been made in TB control, although the AIDS epidemic, loss of public health infrastructure, and the threat of multi-drug resistant disease allow TB to remain a threat. Around the world, M. tuberculosis infects one-third of the population and causes two million deaths per year.
How is TB transmitted?
The bacteria that cause TB are transmitted from one person to another when an infectious person talks, coughs, or sneezes. A person is only considered infectious when they have active TB disease of the lungs (pulmonary TB), especially when M. tuberculosis can be found in their sputum. A person with latent TB disease is not considered infectious. The bacteria do not remain alive in the air for very long, and therefore prolonged close contact is usually required. However, cases of brief and/or contact have been occasionally documented.
What are the symptoms of TB?
When a person develops pulmonary TB, the classic symptoms are:
- Cough lasting longer than 3 weeks
- Coughing up blood
- Weakness and fatigue
- Weight loss
- Lack of appetite
- Night sweats
If a person develops TB disease outside of the lungs (this happens in approximately 25% of all TB cases in the US), the symptoms may be less specific, and will more likely involve the area infected, as well as the last 6 symptoms on the list.
How is TB diagnosed?
In order to diagnose TB, several steps must be taken. First a TB skin test may be administered to determine if the body has been infected with the TB bacteria. If this test is positive and the person is showing symptoms of active TB disease, he or she will be asked to give a sample of their sputum to test for the presence of TB bacteria. A medical exam and a chest x-ray will also be taken to check for the presence of TB disease. Based on the laboratory results and the physical exam, a diagnosis of TB will be made.
Should an infection of TB be suspected that is outside of the lungs, the specific diagnostic steps will vary, although the TB skin test will still be administered.
How is TB treated?
Because the bacterium that causes TB grows very slowly, it also takes a long time for the anti-TB antibiotics to kill the bacteria. For that reason, the course of antibiotics to treat TB usually lasts 6-9 months, occasionally longer. It is necessary to complete the entire course of antibiotics when you have TB, even if you start feeling better, to make sure that all of the TB bacteria in your body are killed.
Usually, a person with simple pulmonary TB is treated with a course of four antibiotics for two months, followed by two antibiotics for four to seven months. A person who is HIV-positive and also infected with TB will typically take slightly different antibiotics for a longer period of time to decrease side effects and interaction with HIV medications, as well as to ensure that all of the TB bacteria are killed.
To help a person remember to take all of their anti-TB medication, and to allow them to take fewer doses of antibiotics per week, Directly Observed Therapy (DOT) may be used. A person from Monroe County Health Department will meet with you twice a week at a location of your choosing and watch you take your medicine. They can also answer any questions you may have about your TB treatment.
How can I prevent TB?
Right now, the best thing you can do to prevent TB disease is to get treated if you have a latent infection. Although there is a vaccine to help prevent TB (the BCG vaccine), it is not routinely administered in the US because it would interfere with reading TB skin tests, and has not been proven effective in preventing adult pulmonary TB, the main form of TB in this country.
As well, if you currently have active TB disease, by staying at home until you are no longer infectious, and by taking all of your medications as prescribed, you can prevent others from becoming infected with TB.
CDC Info on tuberculosis:
TB-Related links (provided by CDC):
Stop TB Foundation:
Q & A About TB from Michigan Department of Community Health: