Many Americans assume tuberculosis is a disease of the past, but the reality is one-third of the world's population is infected with TB - an estimated 10 to 15 million people in the United States alone. Second Opinion explores this historic disease and what you need to know to protect yourself.
Tuberculosis is not a disease of the past
Many scholars have remarked that tuberculosis was to the 19th century what cancer was to the 20th, the most widespread and most feared deadly disease. It was called "consumption" then, and even appeared in popular literature, drama, and opera, where it claimed many a tragic heroine and hero. More importantly, it was the leading cause of death in the U.S.
That seems so long ago – and that may be the greatest danger from tuberculosis (TB) today. We think of it as a disease of the past, no longer relevant. Unfortunately, that's just not true. According to the World Health Organization (WHO) about two billion people, one third of the world's population, have TB bacteria.
What is tuberculosis?
People can have the bacteria, but have no symptoms; that's called latent TB. When symptoms appear, they're said to have active TB. (For more information about TB symptoms, go to Key Point 1.) About 10% of people with latent TB may develop the active form at some time in their lives. The risk of developing it is greatest during their first year of being infected, but it can happen many years later. WHO says every year eight million people worldwide develop active TB, and nearly two million die.
Known as Mycobacterium tuberculosis (or M. tuberculosis), the TB bacterium usually attacks the lungs; TB in the lungs is called pulmonary TB. But the disease also targets the kidneys, spine, lymph nodes, urinary tract, central nervous system, brain, bones, joints, and just about any other area of the body. However, only active pulmonary TB is infectious - that is, it can spread to other people. Usually it spreads through the air. When a person with active pulmonary TB of the lungs coughs, sneezes, spits, sings, talks, laughs, etc., the bacteria are carried on tiny droplets. But normally one sneeze is not enough to infect someone else; other people need a lot of exposure to an infected person before becoming infected themselves. That being said, there's always exceptions to the rule.
Treatment of tuberculosis
Perhaps the single most important thing to remember about TB is that it is caused by bacteria. That means it can be treated by antibiotics. People with latent TB can take medicines to prevent it from becoming active, and people with active TB can take medicines that will cure them. However, for these treatments to be effective, the prescription must be followed scrupulously. (For more information about TB treatments, go to Key Point 3.)
It's because TB is so curable that we think of it as a disease of the past. After the first antibiotics to treat it were developed in the 1940s, the number of cases in the U.S. declined. They declined so much that by the late 70s people thought TB had been eradicated here, and prevention and control efforts were allowed to relax. Funding for TB programs and sanitariums (places where TB patients went to recuperate) was cut, and some sanitariums had to close.
That, plus several other reasons, caused the incidence of TB in America to begin to rise in 1985. These reasons include:
- The worldwide HIV/AIDS epidemic. People's immune systems naturally fight TB bacteria and help prevent the latent condition from becoming active. People with HIV have weakened immune systems and are therefore less able to fight the disease and more likely to develop active TB when they are first infected. Moreover, TB itself can increase the rate at which the AIDS virus replicates. In fact, the sudden onset of TB may be a sign of HIV infection.
- Increased poverty, homelessness, and lack of medical care. Because TB is spread through the air, it spreads easily in the cramped, crowded, badly ventilated areas where the world's poor tend to live. Homeless shelters, prisons, and juvenile detention centers have disproportionally high rates of infection. This situation is worsened by the poor's inability to get good medical care.
- Increased numbers of people in nursing homes. As elderly people's immune systems weaken and general health declines, they may either develop active TB from the bacteria they have had for years or become more susceptible to new infection.
- Increased number of drug-resistant strains of TB. There are many strains of TB bacteria and many TB medications. But no medication can fight every strain, and new strains evolve that resist standard medications. The most dangerous are strains that resist two or more anti-TB medications. This situation is worsened by people who do not complete their course of medication. Not taking all the medicine prescribed allows the bacteria to develop resistance and keeps the person sick and infectious (able to spread the disease) longer. For more information about drug resistant TB and TB treatments,
go to Key Point 3.
- Increased numbers of people from countries with high rates of TB. Looking for a better way of life, people come to America from poverty stricken areas with rising rates of TB infection, especially Africa, Asia and Latin America. As many as half the cases of TB reported in America are in people born elsewhere.
Today, although the incidence of tuberculosis in America is again declining, it is not declining as quickly as it once did.
- Every second someone, somewhere, becomes infected with TB bacteria.
- One third of the world's population – about two billion people – is currently infected with TB bacteria.
- Nearly two million people die from TB every year.
- There are two kinds of TB. People who have latent TB have the bacteria, but have no symptoms. People with active TB have symptoms, feel sick, and can infect others.
- About 10% of people with latent TB may develop the active form at some time in their lives.
- Most kinds of TB are completely curable with antibiotics.
- It is more complex and difficult to diagnose and treat people who have HIV/AIDS and TB, but they too can be cured of TB.
- TB treatment programs must be followed exactly. If you stop taking TB medicines before the prescribed time, the TB bacteria can mutate into drug resistant strains.
- Multi-drug resistant TB (MDR-TB) is the most dangerous because it's the most difficult to treat.
- TB is spread through the air, when a person with active pulmonary TB coughs, sneezes, laughs, talks, etc.
- Generally, you need a lot of exposure to an infected person before becoming infected yourself, though there are always exceptions to the rule.
- Symptoms of active pulmonary TB include coughing for three weeks or more, weight and appetite loss, chills, fever, fatigue, and night sweats.
- Tests for TB include skin tests, blood tests, chest x-rays and sputum, blood, and urine cultures.
- Curing TB may require taking several drugs, several times per week, for several months.
- In 2006, the World Health Organization (WHO) launched a global plan to stop TB. One of its core strategies is DOT (Directly Observed Therapy). A DOT program ensures that a TB antibiotic treatment plan is carried out as prescribed because the drugs are given to the patient by a medical professional on an ongoing, regular basis.
Ask Your Doctor
This list of questions is a good starting point for discussion with your doctor. However, it is not a comprehensive list.
- I've noticed these symptoms: list them
- What medical tests should I take to get an accurate diagnosis?
- When will I know the results?
- What do I have to do to prepare for these tests?
- Do these tests have any side effects or risks?
- Will I need more tests later?
- What type of tuberculosis do I have?
- How severe is it?
- Am I infectious (can I spread the disease to other people)?
- How can I make sure I don't spread tuberculosis to others?
- How will my disease be treated?
- What medications will I take?
- When will the treatment start, and how long will it last?
Questions about any medications that may be prescribed.
- What are their names and purposes?
- What time of day do I take them, with food or without, and for how long?
- What are the potential side effects and what should I do if they occur?
- What should I do if I miss a dose?
- Should I swallow it whole or can it be crushed?
- Will this drug interact with any other medications I am currently taking – prescription, over-the-counter, or herbal?
- While taking these medications, should I avoid certain foods, alcohol, or dietary supplements?
- How do I get on a DOT (Directly Observed Therapy) program to make sure I follow the course of treatment exactly as prescribed and for as long as prescribed?
- Do I need to make any life style changes (such as diet, exercise, work or school, etc.) because of my condition?
Key Point 1
Tuberculosis is a huge public health issue, increasing in numbers worldwide and in certain populations right here in the U.S.
The Centers for Disease Control and Prevention (CDC) reported 14,093 cases of active TB in the U.S in 2005. While the overall rate of new TB cases continues to decline, the amount of that decline has fallen from about 7% per year (1993 to 2000) to only 3.8% (2001-2005). Further, the CDC estimates another ten to fifteen million people in the U.S. have latent TB.
The disease is more prevalent among minorities, especially people born outside the U.S. because they had a greater chance of being exposed to the bacteria in their original countries. For example, in 2004, 95% of Asians and 75% of Hispanics living in the U.S. who were born elsewhere were reported to be infected with the TB bacteria.
Although anyone of any age, race, or nationality can contract TB, there are certain risk factors (things that increase your chance of getting a disease), including:
- Lowered immunity. Since your immune system is your first line of defense against TB bacteria, a weakened immune system obviously puts one at greater risk. Things that can weaken your immune system include:
- Long-term drug and alcohol abuse
- Certain other diseases, such as diabetes, silicosis (a lung disease), cancer of the head or neck, leukemia, Hodgkin's disease, and severe kidney disease
- Certain medications, such as corticosteroids, some arthritis and Crohn's disease medicines, some chemotherapy drugs, and drugs used in organ transplants
- Normal aging and illness
- Continued close contact with a person with active TB of the lungs. Occasional contact may not cause you to get TB.
- Poverty, malnutrition, and lack of medical care.
- Country of origin. Certain parts of the world, such as Africa, Asia and Latin America, have a much higher incidence of TB. The countries of the former Soviet Union have a higher incidence of TB that is resistant to two or more antibiotics.
- Living or working in a crowded, poorly ventilated area. These areas make it easier for the bacteria to spread from person to person. Examples include:
- Long-term care facilities and nursing homes
- Immigration centers
- Refugee camps and shelters
- Traveling to areas with a high risk of TB
The two forms of TB are latent (or inactive) and active. Someone with latent TB infection (LTBI):
- Has inactive TB bacteria
- Has no symptoms
- Is not infectious (can't spread the disease to others)
- Should be treated for latent TB to stop it from becoming active
The opposite is true for someone with active TB. He or she:
- Has active TB bacteria.
- Has symptoms and feels sick
- Is infectious (can spread the disease)
- Must be treated for active TB
The immune system is what initially stops latent TB from becoming active TB. When you're infected with TB bacteria, specialized white blood cells (macrophages) surround them and stop them from harming the tissues in your lungs, or wherever they have settled. But if this immune reaction fails, eventually the bacteria will break through and spread. This is the active form of the disease.
By definition, latent TB has no symptoms. But it can be detected, using the tests described in Key Point 2. If you have any of the risk factors mentioned above, you should get tested for TB on a regular basis.
On the other hand, active pulmonary TB does have symptoms, including:
- A bad cough that lasts three weeks or longer
- Coughing up blood or mucus
- Painful coughing or breathing
- Weight loss
- Appetite loss
- Fatigue or weakness
- Night sweats
If you have any of these symptoms on a continuing basis, see your doctor and get tested for TB.
The symptoms of active non-pulmonary TB depend, as you might imagine, on where the bacteria are located. TB in the urinary tract might cause blood in the urine. TB in the spine might cause back pain, etc.
There is a vaccine against TB called BCG (Bacille Calmette Guerin) made from a live weakened bacterium related to M. tuberculosis. WHO (the World Health Organization) recommends vaccinating infants in areas with high rates of TB. But the vaccine is not very effective for adults, and may lead to a false positive result when one is given a skin test for TB. Therefore, it's not used much in the U.S.
Key Point 2
Tuberculosis is transmitted through the air and its transmission is promoted by close living conditions, poor nutrition, and a compromised immune system. However, anyone can get it, so talk to your doctor to find out how often you need to be tested.
The best-known initial test for TB exposure is called the Mantoux tuberculin skin test. A medical professional injects a small amount of fluid (called PPD tuberculin) into the skin of the lower part of your arm. (The injection is so fast, you feel only a pinprick.) After 48 to 72 hours, you return to the health care professional who will "read" the result on your arm. If a hard, red bump or welt over a certain size develops around the injection site, the test result is probably positive, which means you may have been infected with the tuberculosis bacteria.
But the result could be a false positive. A false positive means the test says you have whatever is being tested for (in this case the presence of TB bacteria), when in reality you don't. A false negative is the reverse; the test shows you don't have what is being tested for, when in reality you do. The false positive could be because you had the TB vaccine or have been exposed to a bacterium similar to M. tuberculosis.
Further, even if the result is positive, that means only that you've been exposed to TB bacteria; it does not mean you have active TB. That's why if the result of this test appears positive, you must have further tests.
The test can give a false negative for a number of reasons:
- Your exposure to TB bacteria may be too recent.
- Your immune system may be severely weakened. Many things can cause this, especially HIV/AIDS. For other causes, see Key Point 1.
- You may have had a vaccine with a live virus that interferes with the test.
- Your body may be so overwhelmed by TB bacteria that it can't respond to the skin test.
- The test may have been improperly administered.
Usually, the chance of a false negative is not that high. But diagnosing and treating TB in people with HIV/AIDS is especially complex and difficult. If you know you have HIV/AIDS, you need to be extremely careful and should have the chest X-ray and/or fluid cultures described below.
There is another, newer initial test for TB bacteria - the QuantiFERON® - TB Gold test. The medical professional will get a small blood sample from you, mix it with the bacteria that causes TB, then examine it to see how your immune system reacts to the bacteria. The advantages of this test are that you don't have to return for a reading, and you can usually get the results within a day. But the test is not yet widely available. Again, if this test yields a positive result, you must have further tests.
The tests that normally follow a positive initial test include:
- Chest X-ray. This can show areas where your immune system has fought TB bacteria (by surrounding them with specialized white blood cells that prevent them damaging your lungs) or damage caused by active TB bacteria.
- Fluid examination and cultures. You give your doctor samples of your sputum (phlegm and mucus you cough up), and/or blood, urine, and stomach secretions which can then be tested in a variety of ways, including microscopic examination and culturing, for the presence of TB bacteria. If the sample is "cultured," it is placed on a substance that promotes bacteria growth; the bacteria are then tested to see if they respond to TB antibiotics. Tuberculosis bacteria grow very slowly, so a culture test may take up to four weeks before giving a result.
If these tests are positive, you will probably begin a course of antibiotic treatments for TB
For information about treating tuberculosis, go to Key Point 3.
Key Point 3
Tuberculosis is a deadly disease. However there are antibiotics that work very well. Most people who comply with the drug therapy will get better and be cured. There are drugs that work and make a real difference in quality of life.
The presence of TB bacteria is usually confirmed by a positive result from a "culture test" done in a lab. (For information about culture tests, go to Key Point 2.) Tuberculosis bacteria grow very slowly, so it may take up to four weeks to complete a culture test. If the result is positive, it can take another two to three weeks of testing to know which antibiotics to use to treat the specific strain of TB the person has.
The usual treatment for latent TB is an antibiotic called isoniazid (INH). It prevents latent TB from becoming active by killing the TB bacteria in the body. But for the treatment to be effective, you must complete the entire course of medicine as prescribed. Usually that means you take the medicine for about six to nine months. This could be longer for people with HIV/AIDS and for children.
Because long-term use of this drug can have side effects such as hepatitis, a life threatening liver disease, your doctor should watch you closely while you're taking it. To help prevent liver disease, you should also avoid the over-the-counter drug acetaminophen (the generic name for Tylenol and many other popular products) and drinking alcohol while you're taking INH.
Other possible side effects from INH are:
- Abdominal pain, tenderness, or soreness
- Aching joints
- Appetite loss
- Blurred or changed vision
- Easy bleeding and bruising
- Fever for three or more days
- Hearing loss
- Jaundice (yellowish skin or eyes)
- Nausea and vomiting
- Ringing in the ears
- Skin rash
- Tingling fingers or toes
- Tingling or numbness around the mouth
These side effects are not very common, but if you notice any of them, get in touch with your doctor immediately.
The treatment for active TB is more complicated, usually involving taking several medications for a period of several months, possibly six months to a year. Usually, they're some combination of:
- Isoniazid (also used against latent TB)
- Rifampin (trade names: Rifadin; Rimactane)
- Ethambutol (trade name: Myambutol)
- Pyrazinamide (the drug trade named Rifater contains pyrazinamide plus isoniazid, and rifampin)
- Rifapentine (trade named: Priftin), sometimes given during the last four months of treatment
The possible side effects of these drugs (again, not very common) include those listed above for isoniazid plus the following for rifampin:
- Turning urine, saliva, or tears orange
- Increasing your sensitivity to the sun
- Weakening the effectiveness of birth control pills and implants
- Creating withdrawal symptoms in people taking rifampin and methadone
As with latent TB, you must take all the medicine as prescribed, for as long as prescribed, even if you stop feeling sick and/or have no symptoms before you finish the course of treatment. Although you may feel better, if you stop taking the medicines before you're supposed to, the bacteria remain alive in your body. Therefore they can become active again at any time. That means:
- You can become sick again.
- You can become infectious again (able to infect other people).
- Worst of all, the bacteria have time to become drug-resistant; they mutate into forms that have their own immunities to drugs and are able to live despite the medicine.
Drug resistant strains of TB bacteria are obviously much harder to kill and therefore more dangerous. The most dangerous are:
- MDR-TB or multi-drug resistant TB: bacteria that are resistant to isoniazid and rifampin (the two most powerful antibiotics used against TB)
- XDR-TB or extensive drug-resistant TB: bacteria resistant to what MDR-TB resists, plus three or more of the antibiotics used against MDR-TB
They can be treated, but the length of treatment is usually two or more years, and the drugs used can have serious side effects. Further, after the drug treatment is complete, surgery may be needed to remove infected areas or restore damaged lungs.
You will be at greater risk of having or getting MDR-TB if you:
- Don't complete your course of treatment exactly as prescribed
- Have spent extensive time with someone with active MDR-TB
- Develop active TB again, after having taken TB medicine in the past
- Live in a location with a large population of people with MDR-TB
There is a fear in the medical community that if TB bacteria continue to mutate into stronger, more resistant forms, the disease could become incurable. The major cause of that would be people not completing their course of treatment exactly as prescribed. That's why many doctors and clinics use a treatment program called directly observed therapy (DOT).
In a DOT program, you meet regularly (usually several times per week) with a medical professional who watches you take your medications. This ensures that the course of treatment is being followed as prescribed. Further, it allows the medical professional to monitor your progress, watch for side effects, give tests when needed (for example, get a sputum sample for a culture test, to see if the TB bacteria are reacting to the medicines), and generally help you get completely cured as quickly and effectively as possible. Even if you don't follow a DOT program, you will still need to make regular visits to a medical professional for all these other reasons.
Treating people with HIV/AIDS and TB is especially complex and difficult. For one thing, each condition exacerbates the effects of the other. People with HIV/AIDS have a weakened immune system and therefore, if they're infected with TB bacteria, are more likely to develop active TB and MDR-TB. Further, the most effective AIDS drugs interact with the most effective TB antibiotics, reducing the effects of both.
However, with careful medical planning to choose the right combination of drugs and careful monitoring to make sure they are working, people with HIV/AIDS can be cured of both latent and active TB. If you know you have HIV/AIDS, get tested for TB by having a chest X-ray and/or the culture tests described in Key Point 2.
Conduct an off-site search for Tuberculosis information from MedlinePlus. These up-to-date search results are based on search terms specific to Second Opinion Key Points.