Tuberculosis

Tuberculosis (TB) is an infectious disease usually caused by the bacterium Mycobacterium tuberculosis (MTB).[1] Tuberculosis generally affects the lungs, but can also affect other parts of the body. Most infections do not have symptoms, known as latent tuberculosis. About 10% of latent infections progress to active disease which, if left untreated, kills about half of those infected. The classic symptoms of active TB are a chronic cough with blood-containing sputum,fevernight sweats, and weight loss.[1] The historical term “consumption” came about due to the weight loss.[2] Infection of other organs can cause a wide range of symptoms. .                                                                          Tuberculosis TB, is an infectious bacterial disease caused by Mycobacterium tuberculosis, which most commonly affects the lungs. It is transmitted from person to person via droplets from the throat and lungs of people with the active respiratory disease.

In healthy people, infection with Mycobacterium tuberculosis often causes no symptoms, since the person’s immune system acts to “wall off” the bacteria. The symptoms of active TB of the lung are coughing, sometimes with sputum or blood, chest pains, weakness, weight loss, fever and night sweats. Tuberculosis is treatable with a six-month course of antibiotics.                                                                                     Tuberculosis (TB) is a potentially serious infectious disease that mainly affects your lungs. The bacteria that cause tuberculosis are spread from one person to another through tiny droplets released into the air via coughs and sneezes.

Once rare in developed countries, tuberculosis infections began increasing in 1985, partly because of the emergence of HIV, the virus that causes AIDS. HIV weakens a person’s immune system so it can’t fight the TB germs. In the United States, because of stronger control programs, tuberculosis began to decrease again in 1993, but remains a concern.

 Pulmonary

If a tuberculosis infection does become active, it most commonly involves the lungs (in about 90% of cases).[11][14] Symptoms may include chest pain and a prolonged cough producing sputum. About 25% of people may not have any symptoms (i.e. they remain “asymptomatic”).[11]Occasionally, people may cough up blood in small amounts, and in very rare cases, the infection may erode into the pulmonary artery or aRasmussen’s aneurysm, resulting in massive bleeding.[3][15] Tuberculosis may become a chronic illness and cause extensive scarring in the upper lobes of the lungs. The upper lung lobes are more frequently affected by tuberculosis than the lower ones.[3] The reason for this difference is not clear.[10] It may be due either to better air flow,[10] or to poor lymph drainage within the upper lungs.[3]

Extrapulmonary

In 15–20% of active cases, the infection spreads outside the lungs, causing other kinds of TB.[16] These are collectively denoted as “extrapulmonary tuberculosis”.[17] Extrapulmonary TB occurs more commonly in immunosuppressed persons and young children. In those with HIV, this occurs in more than 50% of cases.[17] Notable extrapulmonary infection sites include the pleura (in tuberculous pleurisy), the central nervous system (in tuberculous meningitis), the lymphatic system (in scrofula of the neck), the genitourinary system (in urogenital tuberculosis), and the bones and joints (in Pott disease of the spine), among others. When it spreads to the bones, it is also known as “osseous tuberculosis”,[18]a form of osteomyelitis.[10] Sometimes, bursting of a tubercular abscess through skin results in tuberculous ulcer.[19] An ulcer originating from nearby infected lymph nodes is painless, slowly enlarging and has an appearance of “wash leather”.[20] A potentially more serious, widespread form of TB is called “disseminated tuberculosis”, also known as miliary tuberculosis.[3] Miliary TB makes up about 10% of extrapulmonary cases.[21]

Causes

Mycobacteria

 
Scanning electron micrograph of M. tuberculosis

The main cause of TB is Mycobacterium tuberculosis, a small, aerobic, nonmotile bacillus.[3] The high lipid content of this pathogen accounts for many of its unique clinical characteristics.[22] It divides every 16 to 20 hours, which is an extremely slow rate compared with other bacteria, which usually divide in less than an hour.[23]Mycobacteria have an outer membrane lipid bilayer.[24] If a Gram stain is performed, MTB either stains very weakly “Gram-positive” or does not retain dye as a result of the high lipid and mycolic acid content of its cell wall.[25] MTB can withstand weak disinfectants and survive in a dry state for weeks. In nature, the bacterium can grow only within the cells of a host organism, but M. tuberculosis can be cultured in the laboratory.[26]

Using histological stains on expectorated samples from phlegm (also called “sputum”), scientists can identify MTB under a microscope. Since MTB retains certain stains even after being treated with acidic solution, it is classified as an acid-fast bacillus.[10][25] The most common acid-fast staining techniques are the Ziehl–Neelsen stain[27] and the Kinyoun stain, which dye acid-fast bacilli a bright red that stands out against a blue background.[28] Auramine-rhodamine staining[29] andfluorescence microscopy[30] are also used.

The M. tuberculosis complex (MTBC) includes four other TB-causing mycobacteriaM. bovisM. africanumM. canetti, and M. microti.[31] M. africanum is not widespread, but it is a significant cause of tuberculosis in parts of Africa.[32][33] M. bovis was once a common cause of tuberculosis, but the introduction ofpasteurized milk has almost completely eliminated this as a public health problem in developed countries.[10][34] M. canetti is rare and seems to be limited to theHorn of Africa, although a few cases have been seen in African emigrants.[35][36] M. microti is also rare and is seen almost only in immunodeficient people, although its prevalence may be significantly underestimated.[37]

Other known pathogenic mycobacteria include M. lepraeM. avium, and M. kansasii. The latter two species are classified as “nontuberculous mycobacteria” (NTM). NTM cause neither TB nor leprosy, but they do cause pulmonary diseases that resemble TB.[38]

Risk factors

A number of factors make people more susceptible to TB infections. The most important risk factor globally is HIV; 13% of all people with TB are infected by the virus.[39] This is a particular problem insub-Saharan Africa, where rates of HIV are high.[40][41] Of people without HIV who are infected with tuberculosis, about 5–10% develop active disease during their lifetimes;[13] in contrast, 30% of those coinfected with HIV develop the active disease.[13]

Tuberculosis is closely linked to both overcrowding and malnutrition, making it one of the principal diseases of poverty.[11] Those at high risk thus include: people who inject illicit drugs, inhabitants and employees of locales where vulnerable people gather (e.g. prisons and homeless shelters), medically underprivileged and resource-poor communities, high-risk ethnic minorities, children in close contact with high-risk category patients, and health-care providers serving these patients.[42]

Chronic lung disease is another significant risk factor. Silicosis increases the risk about 30-fold.[43] Those who smoke cigarettes have nearly twice the risk of TB compared to nonsmokers.[44]

Other disease states can also increase the risk of developing tuberculosis. These include alcoholism[11] and diabetes mellitus (three-fold increase).[45]

Certain medications, such as corticosteroids and infliximab (an anti-?TNF monoclonal antibody), are becoming increasingly important risk factors, especially in the developed world.[11]

Genetic susceptibility also exists,[46] for which the overall importance remains undefined.[11]

Mechanism

 
Public health campaigns in the 1920s tried to halt the spread of TB.

Transmission

When people with active pulmonary TB cough, sneeze, speak, sing, or spit, they expel infectious aerosol droplets 0.5 to 5.0 µm in diameter. A single sneeze can release up to 40,000 droplets.[47] Each one of these droplets may transmit the disease, since the infectious dose of tuberculosis is very small (the inhalation of fewer than 10 bacteria may cause an infection).[48]

People with prolonged, frequent, or close contact with people with TB are at particularly high risk of becoming infected, with an estimated 22% infection rate.[49] A person with active but untreated tuberculosis may infect 10–15 (or more) other people per year.[50] Transmission should occur from only people with active TB – those with latent infection are not thought to be contagious.[10] The probability of transmission from one person to another depends upon several factors, including the number of infectious droplets expelled by the carrier, the effectiveness of ventilation, the duration of exposure, the virulence of the M. tuberculosis strain, the level of immunity in the uninfected person, and others.[51] The cascade of person-to-person spread can be circumvented by segregating those with active (“overt”) TB and putting them on anti-TB drug regimens. After about two weeks of effective treatment, subjects with nonresistant active infections generally do not remain contagious to others.[49] If someone does become infected, it typically takes three to four weeks before the newly infected person becomes infectious enough to transmit the disease to others.[52]

Pathogenesis

 
Microscopy of tuberculous epididymitis.H&E stain

About 90% of those infected with M. tuberculosis have asymptomatic, latent TB infections (sometimes called LTBI),[53] with only a 10% lifetime chance that the latent infection will progress to overt, active tuberculous disease.[54] In those with HIV, the risk of developing active TB increases to nearly 10% a year.[54] If effective treatment is not given, the death rate for active TB cases is up to 66%.[50]

TB infection begins when the mycobacteria reach the pulmonary alveoli, where they invade and replicate within endosomes of alveolar macrophages.[10][55]Macrophages identify the bacterium as foreign and attempt to eliminate it by phagocytosis. During this process, the bacterium is enveloped by the macrophage and stored temporarily in a membrane-bound vesicle called a phagosome. The phagosome then combines with a lysosome to create a phagolysosome. In the phagolysosome, the cell attempts to use reactive oxygen species and acid to kill the bacterium. However, M. tuberculosis has a thick, waxy mycolic acid capsule that protects it from these toxic substances. M. tuberculosis is able to reproduce inside the macrophage and will eventually kill the immune cell.

The primary site of infection in the lungs, known as the “Ghon focus“, is generally located in either the upper part of the lower lobe, or the lower part of the upper lobe.[10] Tuberculosis of the lungs may also occur via infection from the blood stream. This is known as a Simon focus and is typically found in the top of the lung.[56] This hematogenous transmission can also spread infection to more distant sites, such as peripheral lymph nodes, the kidneys, the brain, and the bones.[10][57] All parts of the body can be affected by the disease, though for unknown reasons it rarely affects the heartskeletal musclespancreas, or thyroid.[58]

 
Robert Carswell‘s illustration of tubercle[59]

Tuberculosis is classified as one of the granulomatous inflammatory diseases. MacrophagesT lymphocytesB lymphocytes, and fibroblasts aggregate to form granulomas, with lymphocytes surrounding the infected macrophages. When other macrophages attack the infected macrophage, they fuse together to form a giant multinucleated cell in the alveolar lumen. The granuloma may prevent dissemination of the mycobacteria and provide a local environment for interaction of cells of the immune system.[60] However, more recent evidence suggests that the bacteria use the granulomas to avoid destruction by the host’s immune system. Macrophages and dendritic cells in the granulomas are unable to present antigen to lymphocytes; thus the immune response is suppressed.[61] Bacteria inside the granuloma can become dormant, resulting in latent infection. Another feature of the granulomas is the development of abnormal cell death (necrosis) in the center of tubercles. To the naked eye, this has the texture of soft, white cheese and is termed caseous necrosis.[60]

If TB bacteria gain entry to the blood stream from an area of damaged tissue, they can spread throughout the body and set up many foci of infection, all appearing as tiny, white tubercles in the tissues.[62] This severe form of TB disease, most common in young children and those with HIV, is called miliary tuberculosis.[63]People with this disseminated TB have a high fatality rate even with treatment (about 30%).[21][64]

In many people, the infection waxes and wanes. Tissue destruction and necrosis are often balanced by healing and fibrosis.[60] Affected tissue is replaced by scarring and cavities filled with caseous necrotic material. During active disease, some of these cavities are joined to the air passages bronchi and this material can be coughed up. It contains living bacteria, so can spread the infection. Treatment with appropriate antibiotics kills bacteria and allows healing to take place. Upon cure, affected areas are eventually replaced by scar tissue.[60]

 

Diagnosis

 
M. tuberculosis (stained red) in sputum

Active tuberculosis

Diagnosing active tuberculosis based only on signs and symptoms is difficult,[65] as is diagnosing the disease in those who are immunosuppressed.[66] A diagnosis of TB should, however, be considered in those with signs of lung disease or constitutional symptoms lasting longer than two weeks.[66] A chest X-ray and multiplesputum cultures for acid-fast bacilli are typically part of the initial evaluation.[66] Interferon-? release assays and tuberculin skin tests are of little use in the developing world.[67][68] IGRA have similar limitations in those with HIV.[68][69]

A definitive diagnosis of TB is made by identifying M. tuberculosis in a clinical sample (e.g., sputum, pus, or a tissue biopsy). However, the difficult culture process for this slow-growing organism can take two to six weeks for blood or sputum culture.[70] Thus, treatment is often begun before cultures are confirmed.[71]

Nucleic acid amplification tests and adenosine deaminase testing may allow rapid diagnosis of TB.[65] These tests, however, are not routinely recommended, as they rarely alter how a person is treated.[71] Blood tests to detect antibodies are not specific or sensitive, so they are not recommended.[72]

Latent tuberculosis

 

The Mantoux tuberculin skin test is often used to screen people at high risk for TB.[66] Those who have been previously immunized may have a false-positive test result.[73] The test may be falsely negative in those with sarcoidosisHodgkin’s lymphomamalnutrition, and most notably, active tuberculosis.[10] Interferon gamma release assays (IGRAs), on a blood sample, are recommended in those who are positive to the Mantoux test.[71] These are not affected by immunization or most environmental mycobacteria, so they generate fewer false-positive results.[74] However, they are affected by M. szulgaiM. marinum, and M. kansasii.[75]IGRAs may increase sensitivity when used in addition to the skin test, but may be less sensitive than the skin test when used alone.[76]

Symptoms

Although your body may harbor the bacteria that cause tuberculosis, your immune system usually can prevent you from becoming sick. For this reason, doctors make a distinction between:

  • Latent TB. In this condition, you have a TB infection, but the bacteria remain in your body in an inactive state and cause no symptoms. Latent TB, also called inactive TB or TB infection, isn’t contagious. It can turn into active TB, so treatment is important for the person with latent TB and to help control the spread of TB. An estimated 2 billion people have latent TB.
  • Active TB. This condition makes you sick and can spread to others. It can occur in the first few weeks after infection with the TB bacteria, or it might occur years later.

Signs and symptoms of active TB include:

  • Coughing that lasts three or more weeks
  • Coughing up blood
  • Chest pain, or pain with breathing or coughing
  • Unintentional weight loss
  • Fatigue
  • Fever
  • Night sweats
  • Chills
  • Loss of appetite

Tuberculosis can also affect other parts of your body, including your kidneys, spine or brain. When TB occurs outside your lungs, signs and symptoms vary according to the organs involved. For example, tuberculosis of the spine may give you back pain, and tuberculosis in your kidneys might cause blood in your urine.

When to see a doctor

See your doctor if you have a fever, unexplained weight loss, drenching night sweats or a persistent cough. These are often signs of TB, but they can also result from other medical problems. Your doctor can perform tests to help determine the cause.

The Centers for Disease Control and Prevention recommends that people who have an increased risk of tuberculosis be screened for latent TB infection. This recommendation includes:

  • People with HIV/AIDS
  • IV drug users
  • Those in contact with infected individuals
  • Health care workers who treat people with a high risk of TB

Causes

Tuberculosis is caused by bacteria that spread from person to person through microscopic droplets released into the air. This can happen when someone with the untreated, active form of tuberculosis coughs, speaks, sneezes, spits, laughs or sings.

Although tuberculosis is contagious, it’s not easy to catch. You’re much more likely to get tuberculosis from someone you live with or work with than from a stranger. Most people with active TB who’ve had appropriate drug treatment for at least two weeks are no longer contagious.

HIV and TB

Since the 1980s, the number of cases of tuberculosis has increased dramatically because of the spread of HIV, the virus that causes AIDS. Infection with HIV suppresses the immune system, making it difficult for the body to control TB bacteria. As a result, people with HIV are many times more likely to get TB and to progress from latent to active disease than are people who aren’t HIV positive.

Drug-resistant strains of tuberculosis emerge when an antibiotic fails to kill all of the bacteria it targets. The surviving bacteria become resistant to that particular drug and frequently other antibiotics as well. Some TB bacteria have developed resistance to the most commonly used treatments, such as isoniazid and rifampin.

Some strains of TB have also developed resistance to drugs less commonly used in TB treatment, such as the antibiotics known as fluoroquinolones, and injectable medications including amikacin, kanamycin and capreomycin. These medications are often used to treat infections that are resistant to the more commonly used drugs.

Risk factors

Anyone can get tuberculosis, but certain factors can increase your risk of the disease. These factors include:

Weakened immune system

A healthy immune system often successfully fights TB bacteria, but your body can’t mount an effective defense if your resistance is low. A number of diseases and medications can weaken your immune system, including:

  • HIV/AIDS
  • Diabetes
  • Severe kidney disease
  • Certain cancers
  • Cancer treatment, such as chemotherapy
  • Drugs to prevent rejection of transplanted organs
  • Some drugs used to treat rheumatoid arthritis, Crohn’s disease and psoriasis
  • Malnutrition
  • Very young or advanced age

Traveling or living in certain areas

The risk of contracting tuberculosis is higher for people who live in or travel to countries that have high rates of tuberculosis and drug-resistant tuberculosis, including:

  • Africa
  • Eastern Europe
  • Asia
  • Russia
  • Latin America
  • Caribbean Islands

Poverty and substance abuse

  • Lack of medical care. If you receive a low or fixed income, live in a remote area, have recently immigrated to the United States, or are homeless, you may lack access to the medical care needed to diagnose and treat TB.
  • Substance abuse. IV drug use or alcohol abuse weakens your immune system and makes you more vulnerable to tuberculosis.
  • Tobacco use. Using tobacco greatly increases the risk of getting TB and dying of it.

Where you work or live

  • Health care work.Regular contact with people who are ill increases your chances of exposure to TB bacteria. Wearing a mask and frequent hand-washing greatly reduce your risk.
  • Living or working in a residential care facility.People who live or work in prisons, immigration centers or nursing homes are all at a higher risk of tuberculosis. That’s because the risk of the disease is higher anywhere there is overcrowding and poor ventilation.
  • Living in a refugee camp or shelter. Weakened by poor nutrition and ill health and living in crowded, unsanitary conditions, refugees are at especially high risk of tuberculosis infection.

Complications

Without treatment, tuberculosis can be fatal. Untreated active disease typically affects your lungs, but it can spread to other parts of your body through your bloodstream. Examples of tuberculosis complications include:

  • Spinal pain. Back pain and stiffness are common complications of tuberculosis.
  • Joint damage.Tuberculous arthritis usually affects the hips and knees.
  • Swelling of the membranes that cover your brain (meningitis).This can cause a lasting or intermittent headache that occurs for weeks. Mental changes also are possible.
  • Liver or kidney problems. Your liver and kidneys help filter waste and impurities from your bloodstream. These functions become impaired if the liver or kidneys are affected by tuberculosis.
  • Heart disorders. Rarely, tuberculosis can infect the tissues that surround your heart, causing inflammation and fluid collections that may interfere with your heart’s ability to pump effectively. This condition, called cardiac tamponade, can be fatal.
  • interfere with your heart’s ability to pump effectively. This condition, called cardiac tamponade, can be fatal.
  • Image result for tuberculosisImage result for tuberculosisImage result for tuberculosisImage result for tuberculosis

Prevention

Tuberculosis prevention and control efforts rely primarily on the vaccination of infants and the detection and appropriate treatment of active cases.[11] The World Health Organization has achieved some success with improved treatment regimens, and a small decrease in case numbers.[11]

Diagnosis of tuberculosis10

To check for TB, a health care provider will use a stethoscope to listen to the lungs and will check for swelling in the lymph nodes. They will also ask about symptoms and medical history as well as assessing a person’s risk of exposure to TB.

The most common diagnostic test for TB is a skin test where a small injection of PPD tuberculin, an extract of the TB bacterium, is made just below the inside forearm.

The injection site should be checked after 2-3 days, and if a hard, red bump has swollen up then it is likely that TB is present.

Woman having injection
TB is most commonly diagnosed via a skin test involving an injection into the forearm.

Unfortunately, the skin test is not 100% accurate and has been known to give incorrect positive and negative readings.

However, there are other tests that are available to diagnose TB. Blood tests, chest X-rays and sputum tests can all be used to test for the presence of TB bacteria, and may be used alongside a skin test.

MDR-TB is more difficult to diagnose than regular TB. It is also difficult to diagnose regular TB in children.5

Treatments for tuberculosis511

The majority of TB cases can be cured when the right medication is available and administered correctly.

The precise type and length of antibiotic treatment depends on a person’s age, overall health, potential resistance to drugs, whether the TB is latent or active, and the location of infection (i.e. the lungs, brain, kidneys).

People with latent TB may need just one kind of TB antibiotics, whereas people with active TB (particularly MDR-TB) will often require a prescription of multiple drugs.

Antibiotics are usually required to be taken for a relatively long time. The standard length of time for a course of TB antibiotics is about 6 months.

All TB medication is toxic to the liver, and although side effects are uncommon, when they do occur, they can be quite serious. Potential side effects should be reported to a health care provider and include:

  • Dark urine
  • Fever
  • Jaundice
  • Loss of appetite
  • Nausea and vomiting.

It is important for any course of treatment to be completed fully, even if the TB symptoms have gone away. Any bacteria that have survived the treatment could become resistant to the medication that has been prescribed, and could lead to developing MDR-TB in the future.

Directly observed therapy (DOT) can be recommended. It involves a health care worker administering the TB medication to ensure that the course of treatment is completed.

Prevention of tuberculosis11

Face mask
If you have active TB, a face mask can help lower the risk of the disease spreading to other people.

A few general measures can be taken to prevent the spread of active TB. Avoiding other people by not going to school or work, or sleeping in the same room as someone, will help to minimize the risk of germs from reaching anyone else. Wearing a mask, covering the mouth and ventilating rooms can also limit the spread of bacteria.

In some countries, BCG injections are given to children in order to vaccinate them against tuberculosis. It is not recommended for general use in the US because it is not effective in adults, and it can adversely influence the results of skin testing diagnoses.

The most important thing to do is to finish entire courses of medication when they are prescribed. MDR-TB bacteria are far deadlier than regular TB bacteria. Some cases of MDR-TB require extensive courses of chemotherapy, which can be expensive and cause severe adverse drug reactions in patients

Vaccines

The only available vaccine as of 2011 is Bacillus Calmette-Guérin (BCG).[77] In children it decreases the risk of getting the infection by 20% and the risk of infection turning into disease by nearly 60%.[78]

It is the most widely used vaccine worldwide, with more than 90% of all children being vaccinated.[11] The immunity it induces decreases after about ten years.[11] As tuberculosis is uncommon in most of Canada, the United Kingdom, and the United States, BCG is administered only to those people at high risk.[79][80][81] Part of the reasoning against the use of the vaccine is that it makes the tuberculin skin test falsely positive, reducing the test’s use in screening.[81] A number of new vaccines are currently in development.[11]

Public health

The World Health Organization declared TB a “global health emergency” in 1993,[11] and in 2006, the Stop TB Partnership developed a Global Plan to Stop Tuberculosis that aims to save 14 million lives between its launch and 2015.[82] A number of targets they have set are not likely to be achieved by 2015, mostly due to the increase in HIV-associated tuberculosis and the emergence of multiple drug-resistant tuberculosis.[11] A tuberculosis classification system developed by the American Thoracic Society is used primarily in public health programs.[83]

Management

Treatment of TB uses antibiotics to kill the bacteria. Effective TB treatment is difficult, due to the unusual structure and chemical composition of the mycobacterial cell wall, which hinders the entry of drugs and makes many antibiotics ineffective.[84] The two antibiotics most commonly used are isoniazid and rifampicin, and treatments can be prolonged, taking several months.[51] Latent TB treatment usually employs a single antibiotic,[85] while active TB disease is best treated with combinations of several antibiotics to reduce the risk of the bacteria developing antibiotic resistance.[11] People with latent infections are also treated to prevent them from progressing to active TB disease later in life.[85] Directly observed therapy, i.e., having a health care provider watch the person take their medications, is recommended by the WHO in an effort to reduce the number of people not appropriately taking antibiotics.[86] The evidence to support this practice over people simply taking their medications independently is poor.[87] Methods to remind people of the importance of treatment do, however, appear effective.[88]

New onset

The recommended treatment of new-onset pulmonary tuberculosis, as of 2010, is six months of a combination of antibiotics containing rifampicin, isoniazid, pyrazinamide, and ethambutol for the first two months, and only rifampicin and isoniazid for the last four months.[11] Where resistance to isoniazid is high, ethambutol may be added for the last four months as an alternative.[11                                            ]Fast facts on tuberculosis

Here are some key points about tuberculosis. More detail and supporting information is in the main article.

  • In 2012, 1.3 million people were believed to have died because of tuberculosis with an estimated 8.6 million new cases of TB worldwide.13
  • The World Health Organization estimates that 9 million people a year get sick with TB, with 3 million of these “missed” by health systems.
  • TB is among the top 3 causes of death for women aged 15 to 44.
  • Tuberculosis is caused by bacteria (Mycobacterium tuberculosis) that most often affect the lungs, although it can also affect other organs such as the kidneys and heart.5
  • TB can either be active or latent (where no symptoms occur, and the condition cannot be passed on).
  • TB symptoms (cough, fever, night sweats, weight loss etc.) may be mild for many months, and people ill with TB can infect up to 10-15 other people through close contact over the course of a year.
  • TB is an airborne pathogen, meaning that the bacteria that cause TB can spread through the air from person to person.
  • People with compromised immune systems are most at risk of developing active TB and dying from the disease; people with HIV are 26-31 times more likely to develop TB.
  • Tobacco use has been found to increase the risk of developing active TB with more than 20% of TB cases worldwide attributable to smoking.
  • TB bacteria can develop a resistance to antibiotics that fail to kill them completely.
  • The most common diagnostic test for tuberculosis is a skin test.
  • The majority of TB cases can be cured with antibiotic treatment, with isoniazid and rifampicin the two most powerful, first-line (or standard) anti-TB drugs. TB bacteria can develop a resistance to antibiotics that fail to kill them completely.
  • It is vital that any courses of treatment given are fully completed to increase the chance of successful eradication of infection and to reduce the risk of antibiotic resistance developing.

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