TB FAQ:

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What is TB?

Tuberculosis is a disease caused by bacteria called Mycobacterium tuberculosis. The bacteria can attack any part of the body, but they usually attack the lungs. Tuberculosis (TB) is a contagious disease. Like the common cold, it spreads through the air. Only people who are sick with TB in their lungs are infectious. When infectious people cough, sneeze, talk or spit, they propel TB germs, known as bacilli, into the air. A person needs only to inhale a small number of these to be infected.

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How is TB spread?

TB is spread through the air from one person to another. When a person with TB disease of the lungs or throat coughs, sneezes or even speaks, the TB bacteria enter the air, and people nearby might breathe in these bacteria and become infected.

When a person breathes in TB bacteria, the bacteria can settle in the lungs and begin to multiply. From there, they can move through the blood to other parts of the body, like the kidney, spine, and brain.

TB in the lungs or throat can be infectious. This means that the bacteria can be spread to other people. TB in other parts of the body usually is not infectious.

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What are some of the symptoms of TB disease?

Although people with latent TB infection do not have symptoms and cannot spread TB to others, people with active TB disease may spread TB. People with active TB disease may have an abnormal chest x-ray, a positive sputum smear or culture, and may experience some of the following symptoms:

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How much of a threat is TB?

According to the World Health Organization, TB infection is currently spreading at the rate of one person per second. The disease kills more young people and adults than any other infectious disease and is the world's biggest killer of women. In 1993, WHO declared TB to be a global health emergency. Each year, an estimated eight million to 10 million people contract the disease and about two million people die from it. About one-third of the world's population -- or approximately two billion people -- carry the TB bacteria but most never develop the active disease. Around 10% of people infected with TB actually develop the disease at some point during their lives, but this proportion is changing because of HIV. HIV severely weakens the human immune system and makes people much more vulnerable to TB infection.

The World Health Organization (WHO) estimates that the largest number of new TB cases in 2004 occurred in WHO's South-East Asia Region, which accounted for 33% of incident cases globally. However, the estimated incidence per capita in sub-Saharan Africa is nearly twice that of the South-East Asia Region, at nearly 400 cases per 100,000 population.

It is estimated that 1.7 million deaths resulted from TB in 2004. Both the highest number of deaths and the highest mortality per capita are in the WHO Africa region, where HIV has led to rapid growth of the TB epidemic, and increases the likelihood of dying from TB.

In 2004, estimated per capita TB incidence was stable or falling in five out of six WHO regions, but growing at 0.6% per year globally. The exception is the African region, where TB incidence was still rising, in line with the spread of HIV. However, the number of cases notified from the African region is increasing more slowly each year, probably because the HIV epidemics in African countries are also slowing. In eastern Europe (mostly countries of the former Soviet Union), incidence per capita increased during the 1990s, but peaked around 2001, and has since fallen.

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How is TB disease treated?

TB can almost always be cured with medicine. The most common medicines used to treat TB are:

Treatment for TB depends on whether a person has active TB or latent TB infection. A person who has become infected with TB but does not have active TB might be given preventive therapy. Preventive therapy aims to kill TB bacteria that currently are inactive to prevent them from causing active TB disease in the future.

If a doctor decides a person should have preventive therapy, the usual prescription is a daily dose of INH. The person takes INH for six to nine months -- possibly up to a year for some patients --with periodic checkups to make sure the medicine is being taken as prescribed.

However, when a patient has active TB, several different medicines are needed. Taking several drugs together will do a better job of killing all of the bacteria and preventing them from becoming resistant to the drugs. Many medications are available in fixed-dose combinations (FDC), which combine several medications into a single tablet. WHO strongly recommends the use of FDC tablets for TB treatment.

Patients commonly receive a combination of several drugs -- most frequently INH plus two to three others -- usually for at least six months. The patient will probably notice improvements only a few weeks after starting to take the drugs.

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Is there a vaccine for TB?

Bacille Calmette-Guerin vaccine currently is the only vaccine available for TB. Although this vaccine is not widely used in the United States or Northern Europe, WHO recommends that BCG be given to infants and young children in countries where TB is common. The BCG vaccine does not always protect people from TB, and it should not be given during pregnancy or to children with symptomatic HIV infection.

Although BCG appears to reduce the risk of serious childhood forms of TB, BCG does not seem to be highly effective as people move into adulthood. Efforts to develop a more effective TB vaccine are underway, and researchers hope to make such a vaccine available within a decade.

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What is DOTS?

Directly observed treatment, short-course, or DOTS, is the internationally recommended strategy to control TB. DOTS has five components:

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What is multidrug-resistant TB?

The TB bacteria can become resistant to a drug or several drugs used to treat the disease. Drug resistance can occur when TB patients do not adhere to their prescribed drug regimens, health professionals prescribe an incorrect treatment regimen, or an unreliable drug supply interrupts patients' treatment. This means that the drug can no longer kill the bacteria.

Drug resistance is more common in people who have spent time with someone with drug-resistant TB disease; do not take their medicine regularly; do not take all of their prescribed medicine; develop TB disease after having taken TB medicine in the past; or come from areas where drug-resistant TB is common.

Sometimes the bacteria become resistant to more than one drug. This is called multidrug-resistant TB, or MDR-TB. People with MDR-TB disease must be treated with specific drugs that often are much more expensive than conventional therapy.

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What are the links between HIV and TB?

HIV/AIDS and TB are so closely connected that the terms "co-epidemic" or "dual epidemic" often are used to describe their relationship. The dual epidemic often is called TB/HIV or HIV/TB. HIV affects the immune system and increases the likelihood that people will acquire new TB infection. HIV also can facilitate both the progression of latent TB infection to active disease and relapse of the disease in previously treated patients. TB is one of the leading causes of death in HIV-positive people.

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What is the StopTB strategy?

In 2006, WHO launched the new Stop TB Strategy. The core of this strategy is DOTS, the TB control approach introduced by WHO in 1995. Since then, more than 22 million patients have been treated under DOTS-based services. The new six-point strategy builds on this success, while recognizing the key challenges of TB/HIV and MDR-TB. It also responds to access, equity and quality constraints, and adopts evidence-based innovations in engaging with private health-care providers, empowering affected people and communities and helping to strengthen health systems and promote research.

The six components of the Stop TB Strategy are:

•  Pursuing high-quality DOTS expansion and enhancement. Making high-quality services widely available and accessible to all those who need them, including the poorest and most vulnerable, requires DOTS expansion to even the remotest areas. In 2004, 183 countries (including all 22 of the high-burden countries which account for 80% of the world's TB cases) were implementing DOTS in at least part of the country.

•  Addressing TB/HIV, MDR-TB and other challenges. Addressing TB/HIV, MDR-TB and other challenges requires much greater action and input than DOTS implementation and is essential to achieving the targets set for 2015, including the United Nations Millennium Development Goal relating to TB (Goal 6; Target 8).

•  Contributing to health system strengthening. National TB control programmes must contribute to overall strategies to advance financing, planning, management, information and supply systems and innovative service delivery scale-up.

•  Engaging all care providers. TB patients seek care from a wide array of public, private, corporate and voluntary health-care providers. To be able to reach all patients and ensure that they receive high-quality care, all types of health-care providers are to be engaged.

•  Empowering people with TB, and communities. Community TB care projects have shown how people and communities can undertake some essential TB control tasks. These networks can mobilize civil societies and also ensure political support and long-term sustainability for TB control programmes.

Enabling and promoting research. While current tools can control TB, improved practices and elimination will depend on new diagnostics, drugs and vaccines.

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