infections
Tuberculosis (TB)
Prevention of Tuberculosis
Prevention of tuberculosis has three aspects: Stopping the spread of infection Treating infection as early as possible before it becomes active disease Sometimes vaccination Because tuberculosis bacteria are airborne, good ventilation with fresh air lowers the concentration of bacteria and limits their spread. Also, germicidal ultraviolet lamps can be used to kill airborne tuberculosis bacteria in buildings where people at risk are gathered, such as homeless shelters, jails, and hospital and emergency department waiting areas. If health care workers handle samples of infected tissue or fluid or interact with people who may be infected, they wear specially fitted masks called respirators, which filter the air, to help protect them. No precautions are needed if people have no symptoms even if their skin or blood test for tuberculosis is positive. Most people with active tuberculosis do not need to be hospitalized. However, to help prevent spread of the disease, they should do the following: Stay at home Avoid visitors (they do not have to avoid family members who have already been exposed) Cover their cough with a tissue or cough into their elbow People should follow these precautions until they are responding to treatment and no longer coughing. After only a week or two of treatment with the correct antibiotics, people are less likely to spread the disease. However, if they live or work with people who are at high risk (such as young children or people with AIDS), repeated analyses of sputum samples may be needed to determine when the danger of spreading the infection has passed. Also, people who continue to cough during treatment, do not take their drugs as instructed, or have highly drug-resistant tuberculosis may need to follow these precautions longer so that they do not spread the disease. Directly observed therapy ( Antibiotics ) can also help prevent the spread of infection. Making sure that infected people take the prescribed drugs as instructed increases the chance that the bacteria will be eradicated. Public health personnel try to determine who might have been infected by a person with tuberculosis and recommend that these people be tested for tuberculosis. Because tuberculosis is spread only by people with active disease, treatment of latent disease and early recognition and treatment of active disease are among the best ways to stop it from spreading. Most people who have a positive tuberculin skin or blood test are treated even if they are not yet ill. The antibioticisoniazidis very effective at stopping the infection before it becomes active disease. It is given daily for 9 months. For some people,rifampinalone may be prescribed daily for 4 months. In some countries,isoniazidandrifapentineare used together once a week for 3 months as directly observed therapy. Preventive therapy definitely benefits younger people who have a positive tuberculin skin test. It also is likely to help older people with a positive tuberculin skin test if they are at high risk of tuberculosis—for example, if the any of the following apply: Their skin or blood test recently changed from negative to positive. They have been recently exposed. They have a weakened immune system. For older people with long-standing latent infection, the risk of toxicity from the antibiotics may be greater than the risk of developing tuberculosis. In such cases, doctors often consult an expert in the subject before they decide whether to use preventive therapy. If people have a positive skin or blood test, the risk of developing active infection is high in the following situations: If they become infected with HIV If they take corticosteroids or other drugs that suppress the immune system (including some of the newer anti-inflammatory drugs) Such people usually need treatment of latent tuberculosis infection. In areas of the world where tuberculosis is common, a vaccine called bacille Calmette-Guérin (BCG) is used to do the following: Prevent development of serious complications, such as meningitis Help prevent infection in people who are at high risk of becoming infected withMycobacterium tuberculosis, especially children Doctors usually do not recommend the BCG vaccine for people living in the United States. However, the vaccine may have a role in protecting health care workers and others (particularly children) exposed to tuberculosis that is resistant to two or more drugs. Research is under way to develop a more effective vaccine. People who have received BCG at birth may have a positive reaction to the tuberculin skin test years later, even if they are not infected with tuberculosis bacteria. The effect of BCG vaccination on skin test results is usually smaller than that of tuberculosis, and it lessens with time. About 15 years after BCG vaccination, a positive test result is much more likely to be due to tuberculosis than to BCG vaccination. Nonetheless, people vaccinated at birth often incorrectly attribute a positive skin test later in life to the BCG vaccine. In most countries, tuberculosis is stigmatized, and many people are reluctant to believe that they have even latent infection, much less active disease. Usually, if children who have been vaccinated have a positive tuberculin skin test, doctors presume it is due to tuberculosis and treat it accordingly. Untreated latent infection can have serious complications, especially in children. However, if possible, people who have been vaccinated with BCG should be tested using the Blood test for tuberculosis (IGRA) because the IGRA does not cause a false-positive test result in people who have received the BCG vaccine. This test can also determine whether a positive reaction to a skin test is due to infection with 