What is TB?

Tuberculosis (TB) is caused by bacteria called Mycobacterium tuberculosis.  The bacteria usually attack the lungs, but they can attack any part of the body, including the kidneys, spine, and brain.  Not everyone who gets infected with TB bacteria becomes sick. As a result, there are two types of TB conditions: TB infection and TB disease.

What is TB?

Tuberculosis (TB) is caused by bacteria called Mycobacterium tuberculosis.  The bacteria usually attack the lungs, but they can attack any part of the body, including the kidneys, spine, and brain.  Not everyone who gets infected with TB bacteria becomes sick. As a result, there are two types of TB conditions: TB infection and TB disease.

How TB spreads

When people with TB of the lungs or throat cough, sneeze or spit, they propel the TB bacteria into the air. A non-infected person needs to inhale a few particles  to become infected. People with TB disease often spread TB bacteria to people with whom they spend the most time with, including family members, friends, and coworkers or schoolmates.

TB is NOT spread by:

  1. Shaking someone’s hand
  2. Sharing food or drink
  3. Touching bed linens or toilet seats
  4. Sharing toothbrushes
  5. Kissing

TB Infection

TB bacteria can live in the body without multiplying or making a person sick.  This is called latent TB infection (LTBI) or TB infection.  

People with TB infections:

  1. Have no symptoms
  2. Cannot spread TB bacteria to others

For majority of people with TB infection, the TB bacteria will stay inactive for their entire life and never cause TB disease.  However, for about 5-10% of the people, the TB bacteria will multiply and cause TB disease.

TB Disease

When a person’s immune system cannot stop the TB bacteria from multiplying, it is called TB disease.  People with TB disease can spread TB bacteria to those around them (learn How TB Spreads).  

The symptoms of TB disease vary in presentation and severity depending on how long and where in the body the TB bacteria have been multiplying. Common symptoms of TB disease in the lungs include:

  1. Cough
  2. Pain in the chest
  3. Coughing up blood or sputum (phlegm from deep inside the lungs)
  4. Fever
  5. Unexplained weight loss
  6. Sweating at night
  7. Weakness or fatigue
  8. No appetite
  9. Chills
  10. Swelling

Difference between latent TB infection and TB disease:

TB infection

TB disease

No symptoms

Presents one or more symptoms, including: prolonged cough, chest pain, fever, chills, night sweats, weight loss, loss of appetite

Does not feel sick

Usually feels sick

Not infectious, cannot spread TB bacteria to others

Infectious, may spread TB bacteria to others

Normal chest X-ray and a negative sputum smear

May have an abnormal chest X-ray, or positive sputum smear or Xpert result

Positive TST test or blood test result indicating TB infection

Positive TST test or blood test result indicating TB infection

Needs treatment for latent TB infection to prevent TB disease

Needs treatment to treat TB disease

How TB spreads

When people with TB of the lungs or throat cough, sneeze or spit, they propel the TB bacteria into the air. A non-infected person needs to inhale a few particles  to become infected. People with TB disease often spread TB bacteria to people with whom they spend the most time with, including family members, friends, and coworkers or schoolmates.

TB is NOT spread by:

  1. Shaking someone’s hand
  2. Sharing food or drink
  3. Touching bed linens or toilet seats
  4. Sharing toothbrushes
  5. Kissing

TB Infection

TB bacteria can live in the body without multiplying or making a person sick.  This is called latent TB infection (LTBI) or TB infection.  

People with TB infections:

  1. Have no symptoms
  2. Cannot spread TB bacteria to others

For majority of people with TB infection, the TB bacteria will stay inactive for their entire life and never cause TB disease.  However, for about 5-10% of the people, the TB bacteria will multiply and cause TB disease.

TB Disease

When a person’s immune system cannot stop the TB bacteria from multiplying, it is called TB disease.  People with TB disease can spread TB bacteria to those around them (learn How TB Spreads).  

The symptoms of TB disease vary in presentation and severity depending on how long and where in the body the TB bacteria have been multiplying. Common symptoms of TB disease in the lungs include:

  1. Cough
  2. Pain in the chest
  3. Coughing up blood or sputum (phlegm from deep inside the lungs)
  4. Fever
  5. Unexplained weight loss
  6. Sweating at night
  7. Weakness or fatigue
  8. No appetite
  9. Chills
  10. Swelling

Difference between latent TB infection and TB disease:

TB infection

TB disease

No symptoms

Presents one or more symptoms, including: prolonged cough, chest pain, fever, chills, night sweats, weight loss, loss of appetite

Does not feel sick

Usually feels sick

Not infectious, cannot spread TB bacteria to others

Infectious, may spread TB bacteria to others

Normal chest X-ray and a negative sputum smear

May have an abnormal chest X-ray, or positive sputum smear or Xpert result

Positive TST test or blood test result indicating TB infection

Positive TST test or blood test result indicating TB infection

Needs treatment for latent TB infection to prevent TB disease

Needs treatment to treat TB disease

Preventing TB

Groups at high risk for developing TB disease include:

  1. People with HIV infection
  2. People who became infected with TB bacteria in the last 2 years
  3. Babies and young children
  4. People who inject illegal drugs
  5. People who are sick with other diseases that weaken the immune system
  6. Elderly people
  7. People who were not treated correctly for TB in the past

To minimize the risk of TB infection, individuals should avoid close contact with known TB patients in crowded, enclosed environments such as clinics, hospitals, nursing homes, factories or prisons. 

People working in health care facilities where TB patients are likely to be encountered should consult infection control or occupational health experts and inquire about administrative and environmental procedures for preventing exposure to TB.

Preventing TB

Groups at high risk for developing TB disease include:

  1. People with HIV infection
  2. People who became infected with TB bacteria in the last 2 years
  3. Babies and young children
  4. People who inject illegal drugs
  5. People who are sick with other diseases that weaken the immune system
  6. Elderly people
  7. People who were not treated correctly for TB in the past

To minimize the risk of TB infection, individuals should avoid close contact with known TB patients in crowded, enclosed environments such as clinics, hospitals, nursing homes, factories or prisons. 

People working in health care facilities where TB patients are likely to be encountered should consult infection control or occupational health experts and inquire about administrative and environmental procedures for preventing exposure to TB.

Diagnosing TB

Testing for TB infection

Mantoux Tuberculin Skin Test (TST)

The Mantoux tuberculin skin test (TST) requires two encounters with a healthcare provider.  On the first visit, a small amount of fluid (called tuberculin or purified protein derivative [PPD]) is injected into the skin on the lower part of the arm.  The person being tested must return within 48 to 72 hours to have a health care worker assess the injection site. If a raised, hard area or swelling of sufficient size appears, this means the person being tested has been infected with TB bacteria.  

Interferon Gamma Release Assay (IGRA)

TB infection can also be tested through TB blood tests, or IGRAs. In Viet Nam, the blood test that is available is the QuantiFERON®–TB Gold Plus test (QFT). Blood tests are the preferred TB test for people who have received the BCG vaccine. A health care provider will draw a patient’s blood and send it to a laboratory for analysis and results.

A positive test confirms that a person has been infected with TB bacteria and should begin TB preventive treatment. 

Testing for TB disease

A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria.  These tests cannot distinguish between TB infection and TB disease. Additional tests, such as a chest X-ray and a sputum examination are then needed to determine whether the person being tested has TB disease. 

Sputum Microscopy

In many countries, including Viet Nam, the commonly used method for diagnosing TB is sputum smear microscopy. Trained laboratory technicians look at sputum samples under a microscope to see if TB bacteria are present. However, smear microscopy detects only half the number of TB cases and cannot detect drug-resistance. 

Xpert MTB/RIF

The Xpert MTB/RIF® is a WHO recommended test which has been increasingly used to test for TB disease since 2010. The test detects TB disease and resistance to rifampicin, a potent first line antitubercular drug, within as little as 2 hours.

Diagnosing TB

Testing for TB infection

Mantoux Tuberculin Skin Test (TST)

The Mantoux tuberculin skin test (TST) requires two encounters with a healthcare provider.  On the first visit, a small amount of fluid (called tuberculin or purified protein derivative [PPD]) is injected into the skin on the lower part of the arm.  The person being tested must return within 48 to 72 hours to have a health care worker assess the injection site. If a raised, hard area or swelling of sufficient size appears, this means the person being tested has been infected with TB bacteria.  

Interferon Gamma Release Assay (IGRA)

TB infection can also be tested through TB blood tests, or IGRAs. In Viet Nam, the blood test that is available is the QuantiFERON®–TB Gold Plus test (QFT). Blood tests are the preferred TB test for people who have received the BCG vaccine. A health care provider will draw a patient’s blood and send it to a laboratory for analysis and results.

A positive test confirms that a person has been infected with TB bacteria and should begin TB preventive treatment. 

Testing for TB disease

A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria.  These tests cannot distinguish between TB infection and TB disease. Additional tests, such as a chest X-ray and a sputum examination are then needed to determine whether the person being tested has TB disease. 

Sputum Microscopy

In many countries, including Viet Nam, the commonly used method for diagnosing TB is sputum smear microscopy. Trained laboratory technicians look at sputum samples under a microscope to see if TB bacteria are present. However, smear microscopy detects only half the number of TB cases and cannot detect drug-resistance. 

Xpert MTB/RIF

The Xpert MTB/RIF® is a WHO recommended test which has been increasingly used to test for TB disease since 2010. The test detects TB disease and resistance to rifampicin, a potent first line antitubercular drug, within as little as 2 hours.

Treating TB infection and TB disease

TB infection 

Regimens for latent TB infection (LTBI) use isoniazid (INH), rifapentine (RPT), or rifampin (RIF). It has been proven that patients are more likely to complete shorter treatment regimens. When possible, healthcare providers should prescribe the more convenient shorter regimens.

Where available, WHO has updated the recommendations for use of once-weekly isoniazid-rifapentine for 12 weeks (3HP) for treatment of latent TB infection.

Drugs

Duration

Frequency

Isoniazid (INH)

6 months

Daily

9 months

Daily

Rifampicin (RIF)

4 months

Daily

Isoniazid (INH) and Rifapentine (RPT) 

3 months

Weekly

TB disease

It is very important for people with TB disease to finish taking all of their anti-TB medicine exactly as prescribed. If medicines are stopped early, TB disease can return (relapse).  If doses or certain medicines are skipped, the TB bacteria can develop drug resistance.

Drug-susceptible TB disease is treated by taking a combination of several anti-TB medicines for at least six months.  The treatment course is split into an intensive phase containing four medicines for two months (eight weeks) and a continuation phase containing two medicines for an additional four months (18 weeks).

Intensive Phase

Continuation Phase

  • Four anti-TB medicines
  • Rifampin (R, RIF)
  • Isoniazid (H, INH)
  • Pyrazinamide (Z, PZA)
  • Ethambutol (E, EMB)
  • Seven days per week for 56 doses (8 weeks)
  • Two anti-TB medicines
  • Rifampin (R, RIF)
  • Isoniazid (H, INH)
  • Seven days per week for 126 doses (18 weeks)

Treating TB infection and TB disease

TB infection 

Regimens for latent TB infection (LTBI) use isoniazid (INH), rifapentine (RPT), or rifampin (RIF). It has been proven that patients are more likely to complete shorter treatment regimens. When possible, healthcare providers should prescribe the more convenient shorter regimens.

Where available, WHO has updated the recommendations for use of once-weekly isoniazid-rifapentine for 12 weeks (3HP) for treatment of latent TB infection.

Drugs

Duration

Frequency

Isoniazid (INH)

6 months

Daily

9 months

Daily

Rifampicin (RIF)

4 months

Daily

Isoniazid (INH) and Rifapentine (RPT) 

3 months

Weekly

TB disease

It is very important for people with TB disease to finish taking all of their anti-TB medicine exactly as prescribed. If medicines are stopped early, TB disease can return (relapse).  If doses or certain medicines are skipped, the TB bacteria can develop drug resistance.

Drug-susceptible TB disease is treated by taking a combination of several anti-TB medicines for at least six months.  The treatment course is split into an intensive phase containing four medicines for two months (eight weeks) and a continuation phase containing two medicines for an additional four months (18 weeks).

Intensive Phase

Continuation Phase

  • Four anti-TB medicines
  • Rifampin (R, RIF)
  • Isoniazid (H, INH)
  • Pyrazinamide (Z, PZA)
  • Ethambutol (E, EMB)
  • Seven days per week for 56 doses (8 weeks)
  • Two anti-TB medicines
  • Rifampin (R, RIF)
  • Isoniazid (H, INH)
  • Seven days per week for 126 doses (18 weeks)

Drug-resistant TB

Drug-resistant TB (DR-TB) disease is caused by TB bacteria which are resistant to at least one of the four first-line anti-TB medicines (rifampin, isoniazid, pyrazinamide or ethambutol).  Drug-resistant TB bacteria are spread the same way as drug-susceptible TB bacteria (through the air).

Causes of drug-resistant TB

Drug-resistant TB can occur when anti-TB medicines are misused or mismanaged. This includes:

  1. People who do not complete a full course of anti-TB treatment
  2. Health care providers who prescribe the wrong treatment (wrong dose or length of time)
  3. When anti-TB medicines are not available (stock out, resulting in treatment interruptions)
  4. When anti-TB medicines are of poor quality

Types of drug-resistant TB

Multidrug-resistant TB (MDR-TB) occurs when the TB bacteria are resistant to both isoniazid and rifampin, the two most potent anti-TB drugs.  Extensively drug-resistant TB (XDR -TB) is a rare type of MDR-TB where the TB bacteria are resistant to both isoniazid and rifampin, plus any fluoroquinolone (e.g. ciprofloxacin, ofloxacin, levofloxacin, etc) and at least one of the three injectable second-line anti-TB medicines (i.e. amikacin, kanamycin, or capreomycin).

Diagnosing drug-resistant TB

For all patients, the initial M. tuberculosis isolate should be tested for drug resistance. It is crucial to identify drug resistance as early as possible to ensure effective treatment. Drug susceptibility patterns should be repeated for patients who do not respond adequately to treatment or who have positive culture results despite 3 months of therapy. Susceptibility results from laboratories should be promptly reported to the primary health care provider and to the state or local TB control program.

Treating drug-resistant TB

Treating and curing drug-resistant TB is complicated.  Drug-resistant TB should be managed by or in close consultation with an expert in the disease.

During the last few years, two new drugs have emerged from the research pipeline – bedaquiline and delamanid, these are indicated for the treatment of drug-resistant TB. WHO has produced interim guidance on the use of these two new drugs. Further, to address challenges in preparing and enabling safe and effective uptake of new drugs or regimens under programmatic conditions in countries, WHO has issued a Policy Implementation Package.

Preventing drug-resistant TB

Preventing development of resistance

Ensuring anti-TB treatment adherence is the best way to prevent the development of new drug-resistant TB bacteria.  People treated for TB should not miss doses or stop their treatment early.

Preventing exposure/infection

Since drug-resistant TB bacteria are spread the same way as drug-susceptible TB bacteria, the same airborne infection control measures are effective at preventing exposure to the TB bacteria (see Preventing TB).  It is also important to diagnose drug-resistant TB quickly and to link people to appropriate treatment, rather than waiting for them to first fail an anti-TB treatment course.  Every person diagnosed with TB should receive a drug susceptibility test (DST).

Preventing disease

The World Health Organization (WHO) does not currently recommend any type of preventative treatment for contacts of people with MDR-TB and national policies are limited, inconsistent and lacking consensus.  However, there is a growing body of evidence which indicates that preventative MDR-TB treatment is feasible and effective (report from the Harvard Medical School’s Center for Global Health Delivery-Dubai).  Several trials are currently being conducted to test the effectiveness of different preventative MDR-TB treatment regimens in children and adults (TB-CHAMP, PHEONIx and V-QUIN), which will hopefully lead to the release of new WHO policy guidance and harmonization of national policies.

Drug-resistant TB

Drug-resistant TB (DR-TB) disease is caused by TB bacteria which are resistant to at least one of the four first-line anti-TB medicines (rifampin, isoniazid, pyrazinamide or ethambutol).  Drug-resistant TB bacteria are spread the same way as drug-susceptible TB bacteria (through the air).

Causes of drug-resistant TB

Drug-resistant TB can occur when anti-TB medicines are misused or mismanaged. This includes:

  1. People who do not complete a full course of anti-TB treatment
  2. Health care providers who prescribe the wrong treatment (wrong dose or length of time)
  3. When anti-TB medicines are not available (stock out, resulting in treatment interruptions)
  4. When anti-TB medicines are of poor quality

Types of drug-resistant TB

Multidrug-resistant TB (MDR-TB) occurs when the TB bacteria are resistant to both isoniazid and rifampin, the two most potent anti-TB drugs.  Extensively drug-resistant TB (XDR -TB) is a rare type of MDR-TB where the TB bacteria are resistant to both isoniazid and rifampin, plus any fluoroquinolone (e.g. ciprofloxacin, ofloxacin, levofloxacin, etc) and at least one of the three injectable second-line anti-TB medicines (i.e. amikacin, kanamycin, or capreomycin).

Diagnosing drug-resistant TB

For all patients, the initial M. tuberculosis isolate should be tested for drug resistance. It is crucial to identify drug resistance as early as possible to ensure effective treatment. Drug susceptibility patterns should be repeated for patients who do not respond adequately to treatment or who have positive culture results despite 3 months of therapy. Susceptibility results from laboratories should be promptly reported to the primary health care provider and to the state or local TB control program.

Treating drug-resistant TB

Treating and curing drug-resistant TB is complicated.  Drug-resistant TB should be managed by or in close consultation with an expert in the disease.

During the last few years, two new drugs have emerged from the research pipeline – bedaquiline and delamanid, these are indicated for the treatment of drug-resistant TB. WHO has produced interim guidance on the use of these two new drugs. Further, to address challenges in preparing and enabling safe and effective uptake of new drugs or regimens under programmatic conditions in countries, WHO has issued a Policy Implementation Package.

Preventing drug-resistant TB

Preventing development of resistance

Ensuring anti-TB treatment adherence is the best way to prevent the development of new drug-resistant TB bacteria.  People treated for TB should not miss doses or stop their treatment early.

Preventing exposure/infection

Since drug-resistant TB bacteria are spread the same way as drug-susceptible TB bacteria, the same airborne infection control measures are effective at preventing exposure to the TB bacteria (see Preventing TB).  It is also important to diagnose drug-resistant TB quickly and to link people to appropriate treatment, rather than waiting for them to first fail an anti-TB treatment course.  Every person diagnosed with TB should receive a drug susceptibility test (DST).

Preventing disease

The World Health Organization (WHO) does not currently recommend any type of preventative treatment for contacts of people with MDR-TB and national policies are limited, inconsistent and lacking consensus.  However, there is a growing body of evidence which indicates that preventative MDR-TB treatment is feasible and effective (report from the Harvard Medical School’s Center for Global Health Delivery-Dubai).  Several trials are currently being conducted to test the effectiveness of different preventative MDR-TB treatment regimens in children and adults (TB-CHAMP, PHEONIx and V-QUIN), which will hopefully lead to the release of new WHO policy guidance and harmonization of national policies.

The TB Epidemic

While TB is more prevalent in developing countries, it occurs in every part of the world. In 2017, 10 million people fell ill with TB, and 1.6 million died from the disease (including 0.3 million among people with HIV). he largest number of new TB cases occurred in the South-East Asia and Western Pacific regions (62% of new cases), followed by the African region (25% of new cases).

In 2017, 87% of new TB cases occurred in the 30 high TB burden countries. Eight  countries accounted for two thirds of the new TB cases: India, China, Indonesia, the Philippines, Pakistan, Nigeria, Bangladesh and South Africa. Viet Nam ranks 16th among countries with the highest TB burden in the world and 13th with the highest MDR-TB burden.

About 3 million people are “missed” each year by health systems and many therefore do not get the TB care that they need and deserve. Many of the missed by health services each year will die, some will get better, and others will continue to infect others they come in contact with. The proportion of missed cases has been steady for the past seven years and continues to accumulate each year. 

Globally, TB incidence is falling at about 2% per year. This needs to accelerate to a 4–5% annual decline to reach the 2020 milestones of the End TB Strategy.

The TB Epidemic

While TB is more prevalent in developing countries, it occurs in every part of the world. In 2017, 10 million people fell ill with TB, and 1.6 million died from the disease (including 0.3 million among people with HIV). he largest number of new TB cases occurred in the South-East Asia and Western Pacific regions (62% of new cases), followed by the African region (25% of new cases).

In 2017, 87% of new TB cases occurred in the 30 high TB burden countries. Eight  countries accounted for two thirds of the new TB cases: India, China, Indonesia, the Philippines, Pakistan, Nigeria, Bangladesh and South Africa. Viet Nam ranks 16th among countries with the highest TB burden in the world and 13th with the highest MDR-TB burden.

About 3 million people are “missed” each year by health systems and many therefore do not get the TB care that they need and deserve. Many of the missed by health services each year will die, some will get better, and others will continue to infect others they come in contact with. The proportion of missed cases has been steady for the past seven years and continues to accumulate each year. 

Globally, the net reduction in the TB incidence rate from 2015 to 2022 was 8.7%, far from the WHO End TB Strategy milestone of a 50% reduction by 2025.

Global Goals

The World Health Assembly passed a resolution in May 2014, approving with full support the new post-2015 End TB Strategy with its ambitious targets as part of the newly adopted Sustainable Development Goals. It serves as a blueprint for countries to reduce TB incidence by 80%, TB deaths by 90%, and to eliminate catastrophic costs for households by 2030. While the strategy is combines holistic mix of health and social interventions, it is not a “one size fits all” approach and its success depends on adaption for diverse country settings. It is both a challenge and an opportunity to addressing the TB epidemic. 

The Strategy outlines three strategic pillars that need to be put in place to effectively end the epidemic:

Pillar 1: integrated patient-centred care and prevention

Pillar 2: bold policies and supportive systems

Pillar 3: intensified research and innovation

The success of the Strategy will depend on countries respecting the following 4 key principles as they implement the interventions outlined in each pillar:

  1. Government stewardship and accountability, with monitoring and evaluation
  2. Strong coalition with civil society organizations and communities
  3. Protection and promotion of human rights, ethics and equity
  4. Adaptation of the strategy and targets at country level, with global collaboration.

Read more about the End TB Strategy here.

Global Goals

The World Health Assembly passed a resolution in May 2014, approving with full support the new post-2015 End TB Strategy with its ambitious targets as part of the newly adopted Sustainable Development Goals. It serves as a blueprint for countries to reduce TB incidence by 80%, TB deaths by 90%, and to eliminate catastrophic costs for households by 2030. While the strategy is combines holistic mix of health and social interventions, it is not a “one size fits all” approach and its success depends on adaption for diverse country settings. It is both a challenge and an opportunity to addressing the TB epidemic. 

The Strategy outlines three strategic pillars that need to be put in place to effectively end the epidemic:

Pillar 1: integrated patient-centred care and prevention

Pillar 2: bold policies and supportive systems

Pillar 3: intensified research and innovation

The success of the Strategy will depend on countries respecting the following 4 key principles as they implement the interventions outlined in each pillar:

  1. Government stewardship and accountability, with monitoring and evaluation
  2. Strong coalition with civil society organizations and communities
  3. Protection and promotion of human rights, ethics and equity
  4. Adaptation of the strategy and targets at country level, with global collaboration.

Read more about the End TB Strategy here.