Tuberculosis

Tuberculosis

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  TUBERCULOSIS Mycobacterium tuberculosis
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  INTRODUCTION • TB isan airborne disease caused by the bacterium Mycobacterium tuberculosis (M. tuberculosis). • Tuberculosis is spread through the air when people who have active TB in their lungs cough, spit, speak, or sneeze. • TB usually affects the lungs, but it can also affect other parts of the body, such as the brain, the kidneys, or the spine. • A person with TB can die if they do not get treatment.
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  TRANSMISSION OF TB •M. tuberculosis is carried in airborne particles, called droplet nuclei, of 1– 5 microns in diameter. Infectious droplet nuclei are generated when persons who have pulmonary or laryngeal TB disease cough, sneeze, shout, or sing. • M. tuberculosis is transmitted through the air, not by surface contact. • Transmission occurs when a person inhales droplet nuclei containing M. tuberculosis, and the droplet nuclei traverse the mouth or nasal passages, upper respiratory tract, and bronchi to reach the alveoli of the lungs. TB is spread from person to person through the air. The dots in the air represent droplet nuclei containing tubercle bacilli.
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  SIGNS AND SYMPTOMSOF TB DISEASE Extra pulmonary TB • M. tuberculosis can infect any organ of the body • Symptoms vary by site of disease • Occurs in immunosuppressed person and young children Pulmonary TB • Cough >2 weeks • Often productive (sputum), can be bloody • Fever • Night sweats • Weight loss • Chest pain
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  Factors that Determinethe Probability of M. tuberculosis Transmission FACTOR 1. Susceptibility 2. Infectiousness 3. Environment 4. Exposure DESCRIPTION 1. Susceptibility (immune status) of the exposed individual 2. Infectiousness of the person with TB disease is directly related to the number of tubercle bacilli that he or she expels into the air. Persons who expel many tubercle bacilli are more infectious than patients who expel few or no bacilli. 3. Environmental factors that affect the concentration of M. tuberculosis organisms. 4. Proximity, frequency, and duration of exposure.
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  RISK FACTORS FORTB DISEASE Low socioeconomic status Homelessness •Cancer Transplantation •Malnutrition Diabetes •Alcoholism HIV infection Diseases, conditions or drugs that weaken the immune system • 10% lifetime risk for developing active TB among HIV uninfected • 10% annual risk for developing active TB among HIV infected TB is the leading cause of death worldwide in HIV infected individuals Major surgical procedures may occasionally trigger dissemination
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  SITES OF TBDISEASE Pulmonary Extrapulmonary Military TB Central Nervous System
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  LATENT TUBERCULOSIS INFECTION(LTBI) • Persons with LTBI have M. tuberculosis in their bodies, but do not have TB disease and cannot spread the infection to other people. • The process of LTBI begins when extracellular bacilli are ingested by macrophages and presented to other white blood cells. This triggers the immune response in which white blood cells kill or encapsulate most of the bacilli, leading to the formation of a granuloma. At this point, LTBI has been established. • LTBI may be detected by using the tuberculin skin test (TST) or an interferon-gamma release assay (IGRA). • It can take 2 to 8 weeks after the initial TB infection for the body’s immune system to be able to react to tuberculin and for the infection to be detected by the TST or IGRA. • Within weeks after infection, the immune system is usually able to halt the multiplication of the tubercle bacilli, preventing further progression.
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  TB DISEASE In somepeople, the tubercle bacilli overcome the immune system and multiply, resulting in progression from LTBI to TB disease. Persons who have TB disease are usually infectious and may spread the bacteria to other people. The progression from LTBI to TB disease may occur at any time, from soon to many years later. Body fluid or tissue from the disease site should be collectedfor AFB smear and culture. Positive culture for M. tuberculosis confirms the diagnosis of TB disease.
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  TB INFECTION V/STB DISEASE
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  TESTING OF TB •There are tests that can be used to help detect TB infection: a skin test or TB blood tests. • The Mantoux tuberculin skin test is performed by injecting a small amount of fluid (called tuberculin) into the skin in the lower part of the arm. • A person given the tuberculin skin test must return within 48 to 72 hours to have a trained health care worker look for a reaction on the arm. • The TB blood tests measures how the patient’s immune system reacts to the germs that cause TB.
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  TREATMENT • TB diseasecan be treated by taking several drugs for 6 to 12 months. • It is very important that people who have TB disease finish the medicine, and take the drugs exactly as prescribed. • If they stop taking the drugs too soon, they can become sick again; if they do not take the drugs correctly, the germs that are still alive may become resistant to those drugs. • TB that is resistant to drugs is harder and more expensive to treat. • In some situations, staff of the local health department meet regularly with patients who have TB to watch them take their medications. • This is called directly observed therapy (DOT). • DOT helps the patient complete treatment in the least amount of time.
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  PREVENTION • Tuberculosis preventionand control efforts rely primarily on the vaccination of infants and the detection and appropriate treatment of active cases. • Vaccines • The only available vaccine as of 2011 is Bacillus Calmette-Guérin (BCG). • In children it decreases the risk of getting the infection by 20% and the risk of infection turning into disease by nearly 60%. • Public health • The World Health Organization declared TB a "global health emergency" in 1993,and in 2006, the Stop TB Partnership developed a Global Plan to Stop Tuberculosis that aimed to save 14 million lives between its launch and 2015. • A number of targets they set were not achieved by 2015, mostly due to the increase in HIV- associated tuberculosis and the emergence of multiple drug-resistant tuberculosis. • A tuberculosis classification system developed by the American Thoracic Society is used primarily in public health programs.