TB the silent killer
By, Ishrat Firdousi,The Financial Express, March 10, 2007
In developed countries, many people think tuberculosis (TB) is a disease of the past. TB, however, is still a leading killer of young adults worldwide. Some 2 billion people-one-third of the world's population-are thought to be infected with TB bacteria, Mycobacterium tuberculosis.
TB is a chronic bacterial infection. It is spread through the air and usually infects the lungs, although other organs and parts of the body can be involved as well. Most people who are infected with M. tuberculosis harbor the bacterium without symptoms (have latent TB), but some will develop active TB disease. According to World Health Organization (WHO) estimates, each year, 8 million people worldwide develop active TB and nearly 2 million die.
One in 10 people who are infected with M. tuberculosis may develop active TB at some time in their lives. The risk of developing active disease is greatest in the first year after infection, but active disease often does not occur until many years later.
TB is primarily an airborne disease. The bacteria are spread from person to person in tiny microscopic droplets when a TB sufferer coughs, sneezes, speaks, sings, or laughs. Only people with active TB can spread the disease to others. People with TB who have been treated with the correct drugs for at least 2 weeks, however, are no longer contagious and do not spread the bacteria to others.
To identify those who may have been exposed to M. tuberculosis, health care providers typically inject a substance called tuberculin under the skin of the forearm. If a red welt forms around the injection site within 72 hours, the person may have been infected. This doesn't necessarily mean he or she has active disease.
If people have an obvious reaction to the skin test, other tests can help to show if they have active TB. In making a diagnosis, doctors rely on symptoms and other physical signs, the person's history of exposure to TB, and X-rays that may show evidence of M. tuberculosis infection.
The health care provider also will take sputum and other samples to see if the TB bacteria will grow in the lab. If bacteria are growing, this positive culture confirms the diagnosis of TB. Because M. tuberculosis grows very slowly, it can take 4 weeks to confirm the diagnosis. An additional 2 to 3 weeks usually are needed to determine which antibiotics to use to treat the disease.
Between 2 to 8 weeks after being infected with M. tuberculosis, a person's immune system responds to the TB germ by walling off infected cells. From then on the body maintains a standoff with the infection, sometimes for years. Most people undergo complete healing of their initial infection, and the bacteria eventually die off. A positive TB skin test, and old scars on a chest X-ray, may provide the only evidence of the infection.
If, however, the body's resistance is low because of aging, infections such as HIV, malnutrition, or other reasons, the bacteria may break out of hiding and cause active TB.
Early symptoms of active TB can include weight loss, fever, night sweats, and loss of appetite. Symptoms may be vague, however, and go unnoticed by the affected person. For some, the disease either goes into remission (halts) or becomes chronic and more debilitating with cough, chest pain, and bloody sputum.
Symptoms of TB involving areas other than the lungs vary, depending upon the organ or area affected. With appropriate antibiotic treatment, TB can be cured in most people. Successful treatment of TB depends on close cooperation between patient and health care provider. Treatment usually combines several different antibiotic drugs that are given for at least 6 months, sometimes for as long as 12 months.
Some people with TB do not get better with treatment because their disease is caused by a TB strain that is resistant to one or more of the standard TB drugs. If that happens, their health care providers will prescribe different drugs and increase the length of treatment.
People who do not take all the required medications can become sick again and spread TB to others. Additionally, when people do not take all the prescribed medicines or skip times when they are supposed to take them, the TB bacteria evolve to outwit the TB antibiotics. Soon those medicines no longer work against the disease. If this happens, the person now has drug-resistant TB.
Some people have disease that is resistant to two or more drugs. This is called multidrug-resistant TB or MDR-TB. This form of TB is much more difficult to cure.
Treatment for MDR-TB often requires the use of special TB drugs, all of which can produce serious side effects. People with MDR-TB may have to take several antibiotics, at least three to which the bacteria still respond, every day for up to 2 years. Even with this treatment, however, between four and six out of 10 patients with MDR-TB will die, which is the same rate seen with TB patients who are not treated.
TB is largely a preventable disease, and adequate ventilation is the most important measure to prevent its transmission in the community.
Health care providers try to identify people infected with M. tuberculosis as early as possible, before they have developed active TB. They will give infected people a medicine called isoniazid (INH) to prevent active disease. This medicine is given every day for 6 to 12 months. INH can cause hepatitis (inflammation of the liver) in a small percentage of people, especially those older than 35 years.
Hospitals and clinics take precautions to prevent the spread of TB, which include using ultraviolet light to sterilize the air, special filters, and special respirators and masks. In hospitals, people with TB are isolated in special rooms with controlled ventilation and airflow until they can no longer spread TB bacteria.
In those parts of the world where the disease is common, WHO recommends that infants receive a vaccine called BCG (Bacille Calmette Guerin) made from a live weakened bacterium related to M. tuberculosis. BCG vaccine prevents M. tuberculosis from spreading within the body, thus preventing TB from developing.
BCG has its drawbacks, however. It does not protect adults very well against TB. In addition, BCG may interfere with the TB skin test, showing a positive skin test reaction in people who have received the vaccine. In countries where BCG vaccine is used, the ability of the skin test to identify people infected with M. tuberculosis is limited. Because of these limitations, U.S. health experts do not recommend BCG for general use in this country.
WHO estimates 11.4 million people worldwide are infected with both M. tuberculosis and HIV (human immunodeficiency virus, which causes AIDS [acquired immunodeficiency disease]). The primary cause of death in those infected with body microbes is from TB, not AIDS.
One of the first signs that a person is infected with HIV may be that he or she suddenly develops TB. This form of TB often occurs in areas outside the lungs, particularly when the person is in the later stages of AIDS.
It is much more likely for people infected with M. tuberculosis and HIV to develop active TB than it is for someone that is only infected with M. tuberculosis. Fortunately, TB disease can be prevented and cured, even in people with HIV infection.
People infected with both MDR-TB and HIV appear to have a more rapid and deadly disease course than do those with MDR-TB only. If no medicines are available, as many as eight out of ten people with both infections may die, often within months of diagnosis.
Diagnosing TB in people with HIV infection is often difficult. They frequently have disease symptoms similar to those of TB and may not react to the standard TB skin test because their immune system does not work properly. X-rays, sputum tests, and physical exams may also fail to show evidence of M. tuberculosis infection with in people infected with HIV.
Source: http://www.financialexpress-bd.com/index3.asp?cnd=3/10/2007§ion_id=10&newsid=54960&spcl=no
In developed countries, many people think tuberculosis (TB) is a disease of the past. TB, however, is still a leading killer of young adults worldwide. Some 2 billion people-one-third of the world's population-are thought to be infected with TB bacteria, Mycobacterium tuberculosis.
TB is a chronic bacterial infection. It is spread through the air and usually infects the lungs, although other organs and parts of the body can be involved as well. Most people who are infected with M. tuberculosis harbor the bacterium without symptoms (have latent TB), but some will develop active TB disease. According to World Health Organization (WHO) estimates, each year, 8 million people worldwide develop active TB and nearly 2 million die.
One in 10 people who are infected with M. tuberculosis may develop active TB at some time in their lives. The risk of developing active disease is greatest in the first year after infection, but active disease often does not occur until many years later.
TB is primarily an airborne disease. The bacteria are spread from person to person in tiny microscopic droplets when a TB sufferer coughs, sneezes, speaks, sings, or laughs. Only people with active TB can spread the disease to others. People with TB who have been treated with the correct drugs for at least 2 weeks, however, are no longer contagious and do not spread the bacteria to others.
To identify those who may have been exposed to M. tuberculosis, health care providers typically inject a substance called tuberculin under the skin of the forearm. If a red welt forms around the injection site within 72 hours, the person may have been infected. This doesn't necessarily mean he or she has active disease.
If people have an obvious reaction to the skin test, other tests can help to show if they have active TB. In making a diagnosis, doctors rely on symptoms and other physical signs, the person's history of exposure to TB, and X-rays that may show evidence of M. tuberculosis infection.
The health care provider also will take sputum and other samples to see if the TB bacteria will grow in the lab. If bacteria are growing, this positive culture confirms the diagnosis of TB. Because M. tuberculosis grows very slowly, it can take 4 weeks to confirm the diagnosis. An additional 2 to 3 weeks usually are needed to determine which antibiotics to use to treat the disease.
Between 2 to 8 weeks after being infected with M. tuberculosis, a person's immune system responds to the TB germ by walling off infected cells. From then on the body maintains a standoff with the infection, sometimes for years. Most people undergo complete healing of their initial infection, and the bacteria eventually die off. A positive TB skin test, and old scars on a chest X-ray, may provide the only evidence of the infection.
If, however, the body's resistance is low because of aging, infections such as HIV, malnutrition, or other reasons, the bacteria may break out of hiding and cause active TB.
Early symptoms of active TB can include weight loss, fever, night sweats, and loss of appetite. Symptoms may be vague, however, and go unnoticed by the affected person. For some, the disease either goes into remission (halts) or becomes chronic and more debilitating with cough, chest pain, and bloody sputum.
Symptoms of TB involving areas other than the lungs vary, depending upon the organ or area affected. With appropriate antibiotic treatment, TB can be cured in most people. Successful treatment of TB depends on close cooperation between patient and health care provider. Treatment usually combines several different antibiotic drugs that are given for at least 6 months, sometimes for as long as 12 months.
Some people with TB do not get better with treatment because their disease is caused by a TB strain that is resistant to one or more of the standard TB drugs. If that happens, their health care providers will prescribe different drugs and increase the length of treatment.
People who do not take all the required medications can become sick again and spread TB to others. Additionally, when people do not take all the prescribed medicines or skip times when they are supposed to take them, the TB bacteria evolve to outwit the TB antibiotics. Soon those medicines no longer work against the disease. If this happens, the person now has drug-resistant TB.
Some people have disease that is resistant to two or more drugs. This is called multidrug-resistant TB or MDR-TB. This form of TB is much more difficult to cure.
Treatment for MDR-TB often requires the use of special TB drugs, all of which can produce serious side effects. People with MDR-TB may have to take several antibiotics, at least three to which the bacteria still respond, every day for up to 2 years. Even with this treatment, however, between four and six out of 10 patients with MDR-TB will die, which is the same rate seen with TB patients who are not treated.
TB is largely a preventable disease, and adequate ventilation is the most important measure to prevent its transmission in the community.
Health care providers try to identify people infected with M. tuberculosis as early as possible, before they have developed active TB. They will give infected people a medicine called isoniazid (INH) to prevent active disease. This medicine is given every day for 6 to 12 months. INH can cause hepatitis (inflammation of the liver) in a small percentage of people, especially those older than 35 years.
Hospitals and clinics take precautions to prevent the spread of TB, which include using ultraviolet light to sterilize the air, special filters, and special respirators and masks. In hospitals, people with TB are isolated in special rooms with controlled ventilation and airflow until they can no longer spread TB bacteria.
In those parts of the world where the disease is common, WHO recommends that infants receive a vaccine called BCG (Bacille Calmette Guerin) made from a live weakened bacterium related to M. tuberculosis. BCG vaccine prevents M. tuberculosis from spreading within the body, thus preventing TB from developing.
BCG has its drawbacks, however. It does not protect adults very well against TB. In addition, BCG may interfere with the TB skin test, showing a positive skin test reaction in people who have received the vaccine. In countries where BCG vaccine is used, the ability of the skin test to identify people infected with M. tuberculosis is limited. Because of these limitations, U.S. health experts do not recommend BCG for general use in this country.
WHO estimates 11.4 million people worldwide are infected with both M. tuberculosis and HIV (human immunodeficiency virus, which causes AIDS [acquired immunodeficiency disease]). The primary cause of death in those infected with body microbes is from TB, not AIDS.
One of the first signs that a person is infected with HIV may be that he or she suddenly develops TB. This form of TB often occurs in areas outside the lungs, particularly when the person is in the later stages of AIDS.
It is much more likely for people infected with M. tuberculosis and HIV to develop active TB than it is for someone that is only infected with M. tuberculosis. Fortunately, TB disease can be prevented and cured, even in people with HIV infection.
People infected with both MDR-TB and HIV appear to have a more rapid and deadly disease course than do those with MDR-TB only. If no medicines are available, as many as eight out of ten people with both infections may die, often within months of diagnosis.
Diagnosing TB in people with HIV infection is often difficult. They frequently have disease symptoms similar to those of TB and may not react to the standard TB skin test because their immune system does not work properly. X-rays, sputum tests, and physical exams may also fail to show evidence of M. tuberculosis infection with in people infected with HIV.
Source: http://www.financialexpress-bd.com/index3.asp?cnd=3/10/2007§ion_id=10&newsid=54960&spcl=no
posted by AIDS-Care-Watch at 2:13 pm
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