Physics

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TUBERCULOSIS
Tuberculosis, commonly known as TB, is a contagious and an often severe airborne disease caused by a bacterial infection. TB typically affects the lungs, but it also may affect any other organ of the body. It is usually treated with a regimen of drugs taken for 6 months to 2 years, depending on the type of infection Tuberculosis was popularly known as consumption for a long time. Scientists know it as an infection caused by M. tuberculosis. In 1882, the microbiologist Robert Koch discovered the tubercle bacillus, at a time when one of every seven deaths in Europe was caused by TB. Because antibiotics were unknown, the only means of controlling the spread of infection was to isolate patients in private sanitoria or hospitals limited to patients with TB—a practice that continues to this day in many countries. The net effect of this pattern of treatment was to separate the study of tuberculosis from mainstream medicine. Entire organizations were set up to study not only the disease as it affected individual patients, but its impact on the society as a whole. At the turn of the twentieth century more than 80% of the population in the United States were infected before age 20, and tuberculosis was the single most common cause of death. By 1938 there were more than 700 TB hospitals in this country A highly contagious infection caused by the bacterium called Mycobacterium tuberculosis. Abbreviated TB. Tubercles (tiny lumps) are a characteristic finding in TB. Diagnosis may be made by skin test, which if positive should will be followed by a chest X-ray to determine the status (active or dormant) of the infection. Tuberculosis is more common in people with immune system problems, such as AIDS, than in the general population. Treatment of active tuberculosis is mandatory by law in the US, and should be available at no cost to the patient through the public health system. It involves a course of antibiotics and vitamins that lasts about six months. It is important to finish the entire treatment, both to prevent reoccurrence and to prevent the development of antibiotic-resistant tuberculosis. Most patients with tuberculosis do not need to be quarantined, but it is sometimes necessary. Although there are millions of new cases of TB each year, not everyone exposed to the bacterium becomes infected nor does everybody infected with it develop clinical symptoms of TB. A genetic region has been discovered to be associated with clinical TB. People with at least one high-risk copy of this genetic region are ten times more likely to develop TB than normal. The genetic region contains a gene, NRAMP1, that is known to be involved in the susceptibility to leprosy, which is caused by a bacterium related to TB. A specific disease caused by infection with Mycobacterium tuberculosis, the tubercle bacillus, which can affect almost any tissue or organ of the body, the most common site of the disease being the lungs. Primary TB is typically a mild or asymptomatic local pulmonary infection. Regional lymph nodes may become involved, but in otherwise healthy people generalized disease does not immediately develop. A cell-mediated immune response arrests the spread of organisms and walls off the zone of infection. Infected tissues and lymph nodes may eventually calcify. The tuberculin skin test result becomes positive within a few weeks and remains positive throughout life. Organisms in a primary lesion remain viable and can become reactivated months or years later to initiate secondary TB. Progression to the secondary stage eventually occurs in 10–15% of people who have had primary TB; in one half of these, progression occurs within 2 years. The risk of reactivation is increased by diabetes mellitus, malnutrition, HIV infection, silicosis, and various systemic or malignant conditions, as well as in patients with alcoholism, IV drug abusers, nursing home residents, and those receiving adrenocortical steroid or immunosuppressive therapy....
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