Prevention of the spread of TB lies primarily in identifying, isolating, and treating those who have it before they pass it on to others.
A vaccine, called BCG (Bacille Calmette-Guérin), is routinely administered in parts of the world where TB is common, although studies have shown that this vaccine will not prevent every case of TB. People vaccinated with BCG have a positive TB skin test, which eliminates the use of the skin test as an indicator of a recent TB infection. The incidence of TB in the US is low, so US health authorities do not recommend the use of the BCG vaccine.
Early detection depends on identifying those at risk and testing them at regular intervals for latent TB infection. It also depends on recognizing, diagnosing, and treating those who progress to active tuberculosis.
If a person is diagnosed with latent TB infection and follow-up testing reveals no indication of active tuberculosis and they are not considered at a high risk for developing active TB, the doctor may decide to simply monitor the person's health at regular intervals (since about 90% of those with latent infections never develop active tuberculosis).
If, however the person is at risk of developing active TB, they will be treated with a six to nine month course of an antimicrobial drug, either isoniazid or rifampin. It is necessary to take it faithfully for the entire treatment period to ensure that all of the bacteria have been killed. The doctor may use lab tests to monitor a person's liver during this time period, since isoniazid and rifampin may affect liver function.
Active tuberculosis must always be treated. Once M. tuberculosis has been positively identified, the doctor will start the infected person on a treatment program that involves taking several drugs for several months. The length of treatment depends on the results of the AFB smears and cultures used to monitor the effectiveness of treatment.
People with HIV who are diagnosed with active TB may require a unique drug regimen. One of the antibiotics, rifampin, is known to interfere with some of the antiretroviral drugs that are used in the treatment of HIV, so a different TB drug may be prescribed.
Although symptoms will often go away after several weeks, it is crucial that the infected person continue to take the drugs for the entire time period. There are a large number of mycobacteria to kill, and it takes several months to make sure that all of them have been eradicated. If treatment is not continued, the TB can come back, and this time it may be more difficult to treat. It may now be resistant to the first-line drugs, requiring treatment for several more months with drugs that have more side effects.
The health community strongly recommends that those with active tuberculosis participate in directly observed therapy (DOT). This involves taking the medication each day, or several days a week, under the supervision of medical personnel. This increases patient compliance with treatment and decreases the number of people who have to be treated again because their TB has returned.
Those who have been exposed to, or diagnosed with, TB that is resistant to one or both of the first-line drugs, rifampin and isoniazid (multidrug- resistant TB, MDR-TB), are prescribed a regimen utilizing second-line drugs.