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Tuberculosis
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International awareness day March 24 |
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Overview
Tuberculosis (TB) is a disease caused by bacteria called Mycobacterium tuberculosis. The bacteria usually attack the lungs. But, TB bacteria can attack any part of the body such as the kidney, spine, and brain. If not treated properly, TB disease can be fatal.
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Causes
The bacterium that causes tuberculosis spreads in microscopic droplets that are released into the air when someone with the untreated, active form of the disease coughs, speaks, laughs, sings or sneezes.
(Details: open / close) | Although tuberculosis is contagious, it's not especially easy to catch. In general, you need long-term contact with an infected person to become infected yourself. You're much more likely to contract tuberculosis from a family member or close co-worker than from a stranger on a bus or in a restaurant. A person with nonresistant active TB who's been effectively treated for at least two weeks is generally no longer contagious. Rarely, a pregnant woman with an active TB disease may pass the bacteria to her fetus. |
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Epidemiology
It is estimated that 2 million people die from TB each year and more than 8 million people develop active TB each year. TB strikes people most often during their most productive years. The disease has reached alarming proportions in Africa, Asia and Latin America. In the last decade, TB cases have increased by about 20%. If this trend continues, there will be a total of 36 million deaths from TB by the year 2020.
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Prevention
In general, TB is a preventable disease. From a public health standpoint, the best way to control TB is to diagnose and treat people with TB infection before they develop active disease and to take careful precautions with people hospitalized with TB. But there are also measures you can take on your own to help protect yourself and others.
(Details: open / close) * Keep your immune system healthy. Make sure you eat plenty of healthy foods, get adequate amounts of sleep and exercise regularly to keep your immune system in top form.
* Get tested regularly. Experts advise getting a skin test annually if you have HIV or another disease that weakens your immune system, live or work in a prison or nursing home, are a health care worker, or have a substantially increased risk of exposure to the disease.
* Consider preventive therapy. If you test positive for latent TB infection, but have no evidence of active TB, talk to your doctor about therapy with isoniazid to reduce your risk of developing active TB in the future. A vaccine, BCG, is available and has been of some benefit in preventing TB.
* Finish your entire course of medication. This is the most important step you can take to protect yourself and others from TB. When you stop treatment early or skip doses, TB bacteria have a chance to develop mutations that are resistant to the most potent TB drugs. The resulting drug-resistant strains are much more deadly and difficult to treat. To help keep your family and friends from getting sick if you have active TB: * Stay home. Don't go to work or school or sleep in a room with other people during the first few weeks of treatment for active TB.
* Ensure adequate ventilation. Open the windows whenever possible to let in fresh air.
* Cover your mouth. It takes two to three weeks of treatment before you're no longer contagious. During that time, be sure to cover your mouth with a tissue any time you laugh, sneeze or cough. Put the dirty tissue in a bag, seal it and throw it away. Also, wearing a mask when you're around other people during the first three weeks of treatment may help lessen the risk of transmission. |
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Symptoms
Tuberculosis is either latent (dormant) or active. * Latent TB means that you have the TB-causing bacteria in your body, but you cannot spread the disease to others. However, you can still develop active TB.
* Active TB means the infection is spreading in your body and, if your lungs are infected, you can spread the disease to others. Symptoms of active TB may include: * Ongoing cough that brings up thick, cloudy, and sometimes bloody mucus from the lungs (sputum).
* Fatigue and weight loss.
* Night sweats and fever.
* Rapid heartbeat.
* Swelling in the neck (when lymph nodes in the neck are infected).
* Shortness of breath and chest pain (in rare cases). Sometimes, when you are first infected, the disease is so mild you don't know you have it. This is also true for people with latent TB because they have no symptoms.
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Diagnosis
The doctor will complete the following tests to diagnose tuberculosis: * Chest x-ray: The most common diagnostic test that leads to the suspicion of infection is a chest x-ray.
(Details: open / close) In primary TB an x-ray will show an abnormality in your mid and lower lung fields, and lymph nodes may be enlarged.
Reactivated TB bacteria infiltrate the upper lobes of your lungs.
Miliary tuberculosis exhibits diffuse nodules. |
* Mantoux skin test:This test helps identify people infected with M tuberculosis but who have no symptoms. A doctor must read the test.
(Details: open / close) | The doctor will inject 5 units of purified protein derivative (PPD) into your skin. If a raised bump of more than 5 mm (0.2 in) appears at the site 48 hours later, the test may be positive. This test can often indicate disease when there is none (false positive). Also, it can show no disease when you may in fact have TB (false negative). |
* Sputum testing: Sputum testing for acid-fast bacilli is the only test that confirms a TB diagnosis. If sputum (the mucus you cough up) is available, or can be induced, a lab test may give a positive result in up to 30% of people with active disease.
(Details: open / close) | Sputum or other bodily secretions such as from your stomach or lung fluid can be cultured for growth of mycobacteria to confirm the diagnosis. It may take 1-3 weeks to detect growth, but 8-12 weeks to be certain. |
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Treatment
The most common drugs used to fight TB are the following: * Isoniazid (INH)
* Pyrazinamide (PZA)
* Rifampin
* Ethambutol Your doctor will determine the best antibiotics for you. Antibiotics must be taken for at least 6 months to kill all the TB bacteria. Taking more than one antibiotic at a time prevents drug-resistant TB .
(Details: open / close) | Treatment for TB disease is relatively safe. Sometimes the drugs may cause side effects. Some side effects are minor problems. The side effects listed below are serious. If you have any of these see your doctor immediately: No appetite, nausea, vomiting, yellowish skin or eyes, fever for 3 days or more, stomach pain, tingling fingers or toes, skin rash, easy bleeding, sore joints, dizziness, tingling or numbness round the mouth, easy bruising, blurred or changed vision, ringing in the ears, hearing loss. It is always best not to drink alcohol while you are taking TB drugs. |
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Illustrations
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Mycobacteria
Kinyoun stain shows presence of mycobacteria in sputum sample
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Mantoux Skin Test
The positive immunologic response to PPD antigen is seen here. The size of the papule is over 2 cm in diameter.
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News
U.S. Unlikely to Meet Target for TB Elimination
Saturday, 2nd February 2008
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Continuous Doctor Care Key to Childhood Screenings
Monday, 10th March 2008
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Scientific Articles (a selection for patients)
Immunization by a bacterial aerosol
Garcia-Contreras L, Wong YL, Muttil P, Padilla D, Sadoff J, Derousse J, Germishuizen WA, Goonesekera S, Elbert K, Bloom BR, Miller R, Fourie PB, Hickey A, Edwards D.
University of North Carolina, Chapel Hill, NC 27599-7360
(Details: open / close) | A bacterial aerosol vaccine has been developed. This vaccine has microstructural properties which are adapted to alter the dispersion and aerosol properties independently. This means that the vaccine is able to provide effective dispersion or spread of the particles as well as allows the alignment of the particles with the airflow. The vaccine was used with the live attenuated tuberculosis vaccine bacille Calmette-Guérin (BCG). Guinea pigs exposed to this vaccine were seen to be far more resistive to infection by active Mycobacterium Tuberculosis bacilli than guinea pigs who had not received this vaccine and guinea pigs who had received the traditional BCG injection. The above is a summarization of the following article:
Full reference of the article: Garcia-Contreras L, Wong YL, Muttil P, Padilla D, Sadoff J, Derousse J, Germishuizen WA, Goonesekera S, Elbert K, Bloom BR, Miller R, Fourie PB, Hickey A, Edwards D. Immunization by a bacterial aerosol.Proc Natl Acad Sci U S A. 2008 Mar 14 |
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Treatment of latent tuberculosis infection in HIV infected persons
Woldehanna S, Volmink J.
(Details: open / close) | Background: Individuals with HIV infection are at an increased risk of developing active tuberculosis. It is known that treatment of latent tuberculosis infection (LTBI), also referred to as preventive therapy or chemoprophylaxis, helps to prevent progression to active disease in human immunodeficiency virus (HIV) negative populations. However, the extent and magnitude of protection (if any) has not been quantified. Objectives: To determine the effectiveness of tuberculosis preventive therapy in reducing the risk of active tuberculosis and death in persons infected with HIV. Method: Scientific databases and referenced lists of articles were searched for relevant material and authors and other researchers in the field were contacted. Studies in which HIV positive individuals were randomly allocated to preventive therapy for TB and placebo, or to alternative TB preventive therapy regimens were selected. Participants could be tuberculin skin test positive or negative, but without active tuberculosis. Main results: 11 trials were included with a total of 8,130 randomized participants. Preventive therapy (any anti-TB drug) versus placebo was associated with a lower incidence of active tuberculosis. This benefit was more pronounced in individuals with a positive tuberculin skin test than in those who had a negative test. Efficacy was similar for all regimens (regardless of drug type, frequency or duration of treatment). However, compared to INH monotherapy (treatment with only Isoniazid), short -course multi-drug regimens (more than one drug) were much more likely to require discontinuation of treatment due to adverse effects. Overall, there was no evidence that preventive therapy versus placebo reduced all-cause mortality, although a favourable trend was found in people with a positive tuberculin test. Conclusions:Treatment of latent tuberculosis infection (LTBI) reduces the risk of active tuberculosis in HIV positive individuals with a positive tuberculin skin test. The choice of regimen will depend on factors such as cost, adverse effects, adherence and drug resistance. Future studies should assess these aspects. The above is a summarization of the following article:
Full reference of the article: Woldehanna S, Volmink J. Treatment of latent tuberculosis infection in HIV infected persons. Cochrane Database of Systematic Reviews 1996, Issue 3. Art. No.: CD000171. DOI: 10.1002/14651858.CD000171.pub2 |
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Medical Journals (for health professionals)
The International Journal of Tuberculosis and Lung Disease
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Indian Journal of Tuberculosis
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