Tuberculosis, MTB, or TB (short for tubercle bacillus), in the past also called phthisis, phthisis pulmonalis, or consumption, is a widespread, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis. Tuberculosis typically attacks the lungs,
but can also affect other parts of the body. It is spread through the
air when people who have an active TB infection cough, sneeze, or
otherwise transmit respiratory fluids through the air. Most infections do not have symptoms, known as latent tuberculosis.
About one in ten latent infections eventually progresses to active
disease which, if left untreated, kills more than 50% of those so
infected.
The classic symptoms of active TB infection are a chronic cough with blood-tinged sputum, fever, night sweats, and weight loss (the last of these giving rise to the formerly common term for the disease, "consumption"). Infection of other organs causes a wide range of symptoms. Diagnosis of active TB relies on radiology (commonly chest X-rays), as well as microscopic examination and microbiological culture of body fluids. Diagnosis of latent TB relies on the tuberculin skin test (TST) and/or blood tests. Treatment is difficult and requires administration of multiple antibiotics over a long period of time. Household, workplace and social contacts are also screened and treated if necessary. Antibiotic resistance is a growing problem in multiple drug-resistant tuberculosis (MDR-TB) infections. Prevention relies on early detection and treatment of cases and on screening programs and vaccination with the bacillus Calmette-Guérin vaccine.
Tuberculosis has a long, rich history, dating back as far as Ancient Egypt, with evidence of its presence found in the preserved spines of Egyptian mummies.1
In the 18th and 19th centuries, a tuberculosis epidemic rampaged throughout Europe and North America,2 before the German microbiologist Robert Koch discovered the microbial causes of tuberculosis in 1882.3
Following Koch's discovery, the development of vaccines and effective drug treatment led to the belief that the disease was almost defeated. Indeed, at one point the United Nations, predicted that tuberculosis (TB) would be eliminated worldwide by 2025.3
However, in the mid-80s, TB cases began to rise once more in the US and worldwide, so much so that in 1993 the World Health Organization (WHO) declared that TB was a global emergency; the first time that a disease had been labelled as such Fortunately, with proper treatment almost all cases of tuberculosis are curable. Cases of TB have decreased in the US since 1993, but the disease remains a concern. Without proper treatment up to two-thirds of people ill with tuberculosis will die.
Doctors make a distinction between two kinds of tuberculosis infection: latent and active. In latent TB, the TB bacteria remain in the body in an inactive state. They cause no symptoms and are not contagious, but they can become active. In active TB, the bacteria do cause symptoms and can be transmitted to others.
About one-third of the world's population is believed to have latent TB. There is a 10% chance of latent TB becoming active TB, but this risk is much higher in people who have compromised immune systems i.e. people living with HIV or malnutrition, or people who smoke.
TB affects all age groups and all parts of the world. However, the disease mostly affects young adults, and people living in developing countries. In 2012, 80% of reported TB cases occurred in just 22 countries
TB is contagious, but it is not easy to catch. The chances of catching TB from someone you live or work with are much higher than from a stranger. Most people with active TB who have received appropriate treatment for at least two weeks are no longer contagious.
Since antibiotics began to be used to fight TB, some strains have become resistant to drugs. Multidrug-resistant TB (MDR-TB) arises when an antibiotic fails to kill all of the bacteria that it targets, with the surviving bacteria developing resistance to that antibiotic and often others at the same time.
MDR-TB is treatable and curable only with the use of very specific anti-TB drugs, which are often limited or not readily available. In 2012, around 450,000 people developed MDR-TB.
HIV suppresses the immune system, making it harder for the body to control TB bacteria. People who are infected with both HIV and TB are around 20-30% more likely to develop active TB than those who do not have HIV.
Tobacco use has also been found to increase the risk of developing active TB. Over 20% of TB cases worldwide are related to smoking
Hyderabad: A team of scientists from city-based Centre for DNA Fingerprinting and Diagnostics (CDFD) have discovered a mycobacterial protein that promises to fight tuberculosis in a novel way.
In the study, the team led by Sanjeev Khosla used the knowledge of epigenetics to open a new frontier in the research on host-Mycobacterium tuberculosis interaction.
Epigenetics defines the process by which the same DNA in different cells of an organism perform different functions. The team has identified a novel mycobacterial protein Rv1988, which is secreted out of the mycobacterium into the host upon infection and localises to the chromatin (DNA-histone complex) in the nucleus of the human cell.
Around six years ago, the team started this research work and further observed that Rv1988 is a methyltransferase enzyme that methylates the histone H3 protein at an arginine amino acid. This methylation epigenetically modulates the transcription of genes, which would have otherwise mounted an immune response against the infecting pathogen," CDFD Director GR Chandak told reporters.
Identification of Rv1988 as an important mycobacterial virulence factor, augurs well not only for it to be a potential target for therapy against mycobacterial infections but also for developing a new biomarker for identification of M-tuberculosis infection in humans, he said.
Rv1988 is important for the pathogen as its deletion in Mycobacterium tuberculosis reduced bacterial survival.
These observations have been confirmed by Rv1988 expression in a non-pathogenic Mycobacterium smegmatis that negatively affected the health of infected mice. This study has recently been published in the prestigious journal 'Nature Communications', Mr Khosla said.
Since arginine amino acid at 42nd position in Rv1988 is normally not known to be methylated by human methyltransferases, methylation of this amino acid can be used as a sensitive marker of mycobacterial infection, he explained.
A patent based on using this novel atypical site of methylation in histone H3 for diagnosis of M-tuberculosis infection has also been filed by CDFD.
The classic symptoms of active TB infection are a chronic cough with blood-tinged sputum, fever, night sweats, and weight loss (the last of these giving rise to the formerly common term for the disease, "consumption"). Infection of other organs causes a wide range of symptoms. Diagnosis of active TB relies on radiology (commonly chest X-rays), as well as microscopic examination and microbiological culture of body fluids. Diagnosis of latent TB relies on the tuberculin skin test (TST) and/or blood tests. Treatment is difficult and requires administration of multiple antibiotics over a long period of time. Household, workplace and social contacts are also screened and treated if necessary. Antibiotic resistance is a growing problem in multiple drug-resistant tuberculosis (MDR-TB) infections. Prevention relies on early detection and treatment of cases and on screening programs and vaccination with the bacillus Calmette-Guérin vaccine.
Tuberculosis has a long, rich history, dating back as far as Ancient Egypt, with evidence of its presence found in the preserved spines of Egyptian mummies.1
In the 18th and 19th centuries, a tuberculosis epidemic rampaged throughout Europe and North America,2 before the German microbiologist Robert Koch discovered the microbial causes of tuberculosis in 1882.3
Following Koch's discovery, the development of vaccines and effective drug treatment led to the belief that the disease was almost defeated. Indeed, at one point the United Nations, predicted that tuberculosis (TB) would be eliminated worldwide by 2025.3
However, in the mid-80s, TB cases began to rise once more in the US and worldwide, so much so that in 1993 the World Health Organization (WHO) declared that TB was a global emergency; the first time that a disease had been labelled as such Fortunately, with proper treatment almost all cases of tuberculosis are curable. Cases of TB have decreased in the US since 1993, but the disease remains a concern. Without proper treatment up to two-thirds of people ill with tuberculosis will die.
What is tuberculosis?
TB is an infectious disease that usually affects the lungs. It is the second greatest killer due to a single infectious agent worldwide, and in 2012, 1.3 million people died from the disease, with 8.6 million falling ill.Doctors make a distinction between two kinds of tuberculosis infection: latent and active. In latent TB, the TB bacteria remain in the body in an inactive state. They cause no symptoms and are not contagious, but they can become active. In active TB, the bacteria do cause symptoms and can be transmitted to others.
About one-third of the world's population is believed to have latent TB. There is a 10% chance of latent TB becoming active TB, but this risk is much higher in people who have compromised immune systems i.e. people living with HIV or malnutrition, or people who smoke.
TB affects all age groups and all parts of the world. However, the disease mostly affects young adults, and people living in developing countries. In 2012, 80% of reported TB cases occurred in just 22 countries
What causes tuberculosis?
The Mycobacterium tuberculosis bacterium causes TB. It is spread through the air when a person with TB (whose lungs are affected) coughs, sneezes, spits, laughs or talks.TB is contagious, but it is not easy to catch. The chances of catching TB from someone you live or work with are much higher than from a stranger. Most people with active TB who have received appropriate treatment for at least two weeks are no longer contagious.
Since antibiotics began to be used to fight TB, some strains have become resistant to drugs. Multidrug-resistant TB (MDR-TB) arises when an antibiotic fails to kill all of the bacteria that it targets, with the surviving bacteria developing resistance to that antibiotic and often others at the same time.
MDR-TB is treatable and curable only with the use of very specific anti-TB drugs, which are often limited or not readily available. In 2012, around 450,000 people developed MDR-TB.
Who is at risk?
People with compromised immune systems are most at risk of developing active tuberculosis.HIV suppresses the immune system, making it harder for the body to control TB bacteria. People who are infected with both HIV and TB are around 20-30% more likely to develop active TB than those who do not have HIV.
Tobacco use has also been found to increase the risk of developing active TB. Over 20% of TB cases worldwide are related to smoking
Hyderabad: A team of scientists from city-based Centre for DNA Fingerprinting and Diagnostics (CDFD) have discovered a mycobacterial protein that promises to fight tuberculosis in a novel way.
In the study, the team led by Sanjeev Khosla used the knowledge of epigenetics to open a new frontier in the research on host-Mycobacterium tuberculosis interaction.
Epigenetics defines the process by which the same DNA in different cells of an organism perform different functions. The team has identified a novel mycobacterial protein Rv1988, which is secreted out of the mycobacterium into the host upon infection and localises to the chromatin (DNA-histone complex) in the nucleus of the human cell.
Around six years ago, the team started this research work and further observed that Rv1988 is a methyltransferase enzyme that methylates the histone H3 protein at an arginine amino acid. This methylation epigenetically modulates the transcription of genes, which would have otherwise mounted an immune response against the infecting pathogen," CDFD Director GR Chandak told reporters.
Identification of Rv1988 as an important mycobacterial virulence factor, augurs well not only for it to be a potential target for therapy against mycobacterial infections but also for developing a new biomarker for identification of M-tuberculosis infection in humans, he said.
Rv1988 is important for the pathogen as its deletion in Mycobacterium tuberculosis reduced bacterial survival.
These observations have been confirmed by Rv1988 expression in a non-pathogenic Mycobacterium smegmatis that negatively affected the health of infected mice. This study has recently been published in the prestigious journal 'Nature Communications', Mr Khosla said.
Since arginine amino acid at 42nd position in Rv1988 is normally not known to be methylated by human methyltransferases, methylation of this amino acid can be used as a sensitive marker of mycobacterial infection, he explained.
A patent based on using this novel atypical site of methylation in histone H3 for diagnosis of M-tuberculosis infection has also been filed by CDFD.
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