tuberculosis?
i need information on tuberculosis, how's it's spread, how long can someone live with it, what does it do to the body, is there a typ e that's not contagious.
Respiratory Diseases - 5 Answers
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1 :
Tuberculosis (commonly abbreviated as TB) is an infectious disease caused by the bacterium Mycobacterium tuberculosis, which most commonly affects the lungs (pulmonary TB) but can also affect the central nervous system (meningitis), lymphatic system, circulatory system (miliary tuberculosis), genitourinary system, bones and joints. Tuberculosis is one of the deadliest and most common major infectious diseases today. In 2004, the prevalence (number of existing cases) of active TB disease was 14.6 million people with an incidence (number of new cases) of 8.9 million people and mortality (number of deaths) of 1.7 million people [1] mostly in developing countries. However, developing countries are not the only places with tuberculosis. There is a rising number of people in the developed world who contract tuberculosis because they have compromised immune systems, typically as a result of immunosuppressive drugs, substance abuse, or HIV/AIDS. These people are at particular risk of tuberculosis infection and active tuberculosis disease. Most of those infected (90%) have asymptomatic latent TB infection (LTBI). There is a 10% lifetime chance that LTBI will progress to TB disease which, if left untreated, will kill more than 50% of its victims. TB is one of the top four infectious killing diseases in the world: TB kills 1.7 million, and malaria kills 2-3 million[footnote needed]. HIV/AIDS, the neglect of TB control programs, and immigration have caused a resurgence of tuberculosis. Multidrug-resistant strains of TB (MDR-TB) and Extensively Drug-Resistant Tuberculosis (XDR-TB)[2] are emerging. The World Health Organization declared TB a global health emergency in 1993, and the Stop TB Partnership proposed a Global Plan to Stop Tuberculosis which aims to save an additional 14 million lives between 2006 and 2015.
2 :
you speaking of TB'S OHHHHHH!
3 :
respiratory TB is the commonest, spreads by respiratory droplets (breathing, coughing). can infect any organ in the body, symptoms depend on the organ infected, same goes for life expectency, lately they have discovered forms that are virtually resistant to any antibiotics known, so this type kills fast, you can try to search more on mayoclinic.com, good luck
4 :
go to: http://en.wikipedia.org/wiki/Tuberculosis http://www.cdc.gov/nchstp/tb/faqs/qa.htm and you will be answered.
5 :
Tuberculosis Tuberculosis (commonly abbreviated as TB) is an infectious disease caused by the bacterium Mycobacterium tuberculosis, which most commonly affects the lungs (pulmonary TB) but can also affect the central nervous system (meningitis), lymphatic system, circulatory system (miliary tuberculosis), genitourinary system, bones and joints. Tuberculosis is one of the deadliest and most common major infectious diseases today. In 2004, the prevalence (number of existing cases) of active TB disease was 14.6 million people with an incidence (number of new cases) of 8.9 million people and mortality (number of deaths) of 1.7 million people [1] mostly in developing countries. However, developing countries are not the only places with tuberculosis. There is a rising number of people in the developed world who contract tuberculosis because they have compromised immune systems, typically as a result of immunosuppressive drugs, substance abuse, or HIV/AIDS. These people are at particular risk of tuberculosis infection and active tuberculosis disease. Most of those infected (90%) have asymptomatic latent TB infection (LTBI). There is a 10% lifetime chance that LTBI will progress to TB disease which, if left untreated, will kill more than 50% of its victims. TB is one of the top four infectious killing diseases in the world: TB kills 1.7 million, and malaria kills 2-3 million[footnote needed]. HIV/AIDS, the neglect of TB control programs, and immigration have caused a resurgence of tuberculosis. Multidrug-resistant strains of TB (MDR-TB) and Extensively Drug-Resistant Tuberculosis (XDR-TB)[2] are emerging. The World Health Organization declared TB a global health emergency in 1993, and the Stop TB Partnership proposed a Global Plan to Stop Tuberculosis which aims to save an additional 14 million lives between 2006 and 2015. The bacterium Acid-fast bacilli (AFB) (shown in red) are tubercle bacilli Mycobacterium tuberculosis.The cause of tuberculosis, Mycobacterium tuberculosis (MTB), is a slow-growing aerobic bacterium that divides every 16 to 20 hours. This is extremely slow compared to other bacteria (although not the slowest), which tend to have division times measured in minutes (among the fastest growing bacteria is a strain of E. coli that can divide roughly every 20 minutes; by contrast, Mycobacterium leprae divides every 20 days). MTB is not classified as either Gram-positive or Gram-negative because it does not have the chemical characteristics of either. If a Gram stain is performed, it stains very weakly Gram-positive or not at all (ghost cells). It is a small rod-like bacillus which can withstand weak disinfectants and can survive in a dry state for weeks but, spontaneously, can only grow within a host organism (in vitro culture of M. tuberculosis took a long time to be achieved, but is nowadays a routine laboratory procedure). MTB is identified microscopically by its staining characteristics: it retains certain stains after being treated with acidic solution, and is thus classified as an "acid-fast bacillus" or AFB. In the most common staining technique, the Ziehl-Neelsen stain, AFB are stained a bright red which stands out clearly against a blue background. Acid-fast bacilli can also be visualized by fluorescent microscopy, and by an auramine-rhodamine stain. The M. tuberculosis complex includes 3 other mycobacteria which can cause tuberculosis: M. bovis, M. africanum and M. microti. The first two are very rare causes of disease and the last one does not cause human disease. Nontuberculous mycobacteria (NTM) are other mycobacteria (besides M. leprae which causes leprosy) which may cause pulmonary disease resembling TB, lymphadenitis, skin disease, or disseminated disease. These include Mycobacterium avium, M. kansasii, and others. Epidemiology One-third of the world population (2 billion people) have latent TB infection; in 2004, around 14.6 million people have active TB disease with 9 million new cases. The annual incidence rate varies enormously, from 356 per 100,000 in Africa to 41 per 100,000 in the Americas.[1] In the UK, incidence ranges from 90 per 100,000 in the centre of Birmingham to less than 5 per 100,000 in rural Hertfordshire. Approximately 1.7 million people died from TB in 2004. The incidence of TB is known to vary with age. In endemic areas, TB is a disease that primarily affects adolescents and young adults (hence the UK policy until recently was to vaccinate with BCG at the age of 12). However, in countries where TB has gone from high to low incidence, TB is mainly a disease of older people, because of the re-activation of latent TB acquired many decade before (as is the situation in the native population of the UK currently). There are a number of known factors that make people more susceptible to TB infection: worldwide the most important of these is HIV. Smoking more than 20 cigarettes a day also increases the risk of TB by two- to four-times.[3] Transmission TB is spread by aerosol droplets expelled by people with active TB disease of the lungs when they cough, sneeze, speak, or spit. Each droplet is 5 µm in diameter and contains 1 to 3 bacilli. Close contacts (people with prolonged, frequent, or intense contact) are at highest risk of becoming infected (typically a 22% infection rate). A person with untreated, active tuberculosis can infect an estimated 20 other people per year. Others at risk include foreign-born from areas where TB is common, immunocompromised patients (eg. HIV/AIDS), residents and employees of high-risk congregate settings, health care workers who serve high-risk clients, medically underserved, low-income populations, high-risk racial or ethnic minority populations, children exposed to adults in high-risk categories, and people who inject illicit drugs. Transmission can only occur from people with active TB disease (not latent TB infection). The probability of transmission depends upon infectiousness of the person with TB (quantity expelled), environment of exposure, duration of exposure, and virulence of the organism. The chain of transmission can be stopped by isolating patients with active disease and starting effective anti-tuberculous therapy. Pathogenesis Most of those infected (90%) have asymptomatic latent TB infection (LTBI). There is a 10% lifetime chance that LTBI will progress to TB disease. If untreated, the death rate for active TB disease is more than 50%. TB infection begins when MTB bacilli reach the pulmonary alveoli, where the mycobacteria replicate at an exponential rate and infect alveolar macrophages. The primary site of infection in the lungs is called the Ghon focus. Bacteria are picked up by dendritic cells, which can transport the bacilli to local (mediastinal) lymph nodes, and then through the bloodstream to the more distant tissues and organs where TB disease could potentially develop: lung apices, peripheral lymph nodes, kidneys, brain, and bone. Tuberculosis is classified as one of the granulomatous inflammatory conditions. Macrophages, T lymphocytes, B lymphocytes and fibroblasts are among the cells that aggregate to form a granuloma, with lymphocytes surrounding infected macrophages. The granuloma functions not only to prevent dissemination of the mycobacteria, but also provides a local environment for communication of cells of the immune system. Within the granuloma, T lymphocytes (CD4+) secrete a cytokine such as interferon gamma, which activates macrophages to destroy the bacteria with which they are infected, making them better able to fight infection. T lymphocytes (CD8+) can also directly kill infected cells. Importantly, bacteria are not eliminated with the granuloma, but can become dormant, resulting in a latent infection. Latent infection can only be diagnosed in a non-immunized person by a tuberculin skin test, which yields a delayed hypersensitivity type response to purified protein derivatives of M. tuberculosis. Those immunized for TB or with past-cleared infection will respond with parallel delayed hypersensitivity to those currently in a state of infection and thus must be used with caution, particularly with regard to persons from countries where TB immunization is common. Another feature of the granulomas of human tuberculosis is the development of cell death, also called necrosis, in the center of tubercles. To the naked eye this has the texture of soft white cheese and was termed caseous necrosis. If TB bacteria gain entry to the blood stream from an area of tissue damage they spread through the body and set up myriad foci of infection, all appearing as tiny white tubercles in the tissues. This is called miliary tuberculosis and has a high rate of fatality. In many patients the infection waxes and wanes. Tissue destruction and necrosis are balanced by healing and fibrosis. Affected tissue is replaced by scarring and cavities filled with cheese-like white necrotic material. During active disease, some of these cavities are in continuity with the air passages bronchi. This material may therefore be coughed up. It contains living bacteria and can pass on infection. Treatment with appropriate antibiotics kills bacteria and allows healing to take place. Affected areas are eventually replaced by scar tissue. Progression In those people in whom TB bacilli overcome the immune system defenses and begin to multiply, there is progression from TB infection to TB disease. This may occur soon after infection (primary TB disease – 1 to 5%) or many years after infection (post primary TB, secondary TB, reactivation TB disease of dormant bacilli – 5 to 9%). The risk of reactivation increases with immune compromise, such as that caused by infection with HIV. In patients co-infected with M. tuberculosis and HIV, the risk of reactivation increases to 10% per year, while in immune competent individuals, the risk is between 5 and 10% in a lifetime. About five percent of infected persons will develop TB disease in the first two years, and another five percent will develop disease later in life. In other words, about 10% of infected persons with normal immune systems will develop TB disease in their lifetime. Some medical conditions increase the risk of progression to TB disease. In HIV infected persons with TB infection, the risk increases to 10% each year instead of 10% over a lifetime. Other such conditions include drug injection (mainly because of the life style of IV Drug users), substance abuse, recent TB infection (within two years) or history of inadequately treated TB, chest X-ray suggestive of previous TB (fibrotic lesions and nodules), diabetes mellitus, silicosis, prolonged corticosteroid therapy and other immunosuppressive therapy, head and neck cancers, hematologic and reticuloendothelial diseases (leukemia and Hodgkin's disease), end-stage renal disease, intestinal bypass or gastrectomy, chronic malabsorption syndromes, or low body weight (10% or more below the ideal). Some drugs, including rheumatoid arthritis drugs that work by blocking tumor necrosis factor-alpha (an inflammation-causing cytokine), raise the risk of causing a latent infection to become active due to the importance of this cytokine in the immune defense against TB. Symptoms TB most commonly affects the lungs (75% or more), where it is called pulmonary TB. Symptoms may include a productive, prolonged cough of more than three weeks duration, chest pain, and hemoptysis. Systemic symptoms include fever, chills, night sweats, appetite loss, weight loss, and easy fatigability. The term consumption arose because sufferers appeared as if they were "consumed" from within by the disease. People from Asian and African descent may have lymph node TB more often than Caucasians. Lymph node TB is not contagious. Extrapulmonary sites include the pleura, central nervous system (meningitis), lymphatic system (scrofula of the neck), genitourinary system, and bones and joints (Pott's disease of the spine). An especially serious form is disseminated, or miliary TB, so named because the lung lesions so-formed resemble millet seeds on x-ray. These are more common in immunosuppressed persons and in young children. Pulmonary TB may co-exist with extrapulmonary TB. Drug resistance Main article: Tuberculosis treatment#Multidrug-resistant tuberculosis Drug-resistant tuberculosis is transmitted in the same way as regular TB. Primary resistance is said to occur in persons who are infected with a resistant strain of TB. A patient with fully-susceptible TB develops secondary resistance (acquired resistance) during TB therapy because of inadequate treatment, i.e. not taking the prescribed regimen appropriately, or using low quality medication. Drug-resistant TB is an important public health issue in many developing countries, as treatment of drug-resistant TB requires the use of more expensive drugs and treatment is longer. Multidrug-resistant TB (MDR-TB) is defined as resistance to the two most effective first line TB drugs: rifampicin (RMP) and isoniazid (INH). Extensively drug-resistant TB (XDR-TB) is defined as MDR-TB what is also resistant to three or more of the six classes of second-line drugs.[2] Diagnosis Main article: Tuberculosis diagnosis A complete medical evaluation for TB must include a medical history, a chest X-ray, and a physical examination. It may also include a tuberculin skin test, a serological test, microbiological smears and cultures. The interpretation of the tuberculin skin test depends upon the person's risk factors for progression of TB infection to TB disease; recommendations on how to interpret tuberculin skin tests varies widely from country to country. Bacteriophage-based assays are among a few new testing procedures that offer the hope of cheap, fast and accurate TB testing for the impoverished countries that need it most. See also:Tuberculosis radiology Treatment Main article: Tuberculosis treatment For all practical purposes, only patients with tuberculosis of the lungs can spread TB to other people. People may become infected with TB but not have active disease: such people are said to have latent TB infection (LTBI) and are not capable of passing the infection on to other people. The reason for treating people with LTBI is to prevent them from progressing to active TB disease later in life (approximately 10% lifetime risk). The distinction is important because treatment options are different for the two groups
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