What is Tuberculosis and how does it spread. How can TB infection be detected. What are the different types of TB tests available. Who should get tested for TB. How are TB test results interpreted. What are the recommendations for TB testing in different populations.

Understanding Tuberculosis: Transmission and Types

Tuberculosis (TB) is a bacterial infection that primarily affects the lungs but can also impact other parts of the body. It spreads through the air when an infected person coughs, speaks, laughs, sings, or sneezes, releasing TB bacteria into the environment. Those nearby may inhale these bacteria, potentially leading to infection.

There are two main types of TB infection:

• Latent TB Infection: Individuals with latent TB have the bacteria in their bodies but are not sick and cannot spread it to others.
• Active TB Disease: People with active TB are ill and can transmit the bacteria to others. They may experience symptoms such as fever, night sweats, cough, and weight loss.

TB Testing Methods: Skin Tests and Blood Tests

To determine if a person has been infected with TB bacteria, healthcare providers use two primary testing methods:

1. Tuberculin Skin Test (TST)

The Mantoux tuberculin skin test involves injecting a small amount of tuberculin into the skin of the lower arm. After 48-72 hours, a healthcare worker examines the injection site for a reaction, measuring any raised, hard area or swelling.

2. Interferon Gamma Release Assay (IGRA)

IGRAs are blood tests that measure the immune system’s response to TB bacteria. Two FDA-approved IGRAs are available in the United States:

• QuantiFERON®–TB Gold In-Tube test (QFT–GIT)
• T–SPOT®.TB test (T–Spot)

Interpreting TB Test Results

Understanding TB test results is crucial for proper diagnosis and treatment. How are TB test results interpreted?

Tuberculin Skin Test (TST) Results

A positive TST result indicates that the person’s body has been infected with TB bacteria. The interpretation depends on the size of the reaction and the individual’s risk factors. A negative TST suggests that latent TB infection or TB disease is unlikely.

IGRA Results

A positive IGRA result means the person has been infected with TB bacteria, while a negative result indicates that latent TB infection or TB disease is improbable. In both cases, additional tests may be necessary to differentiate between latent TB infection and active TB disease.

Who Should Get Tested for TB?

The Centers for Disease Control and Prevention (CDC) and the United States Preventive Services Task Force (USPSTF) recommend TB testing for populations at increased risk of TB infection. Who are these high-risk groups?

• People who have been in close contact with someone who has active TB disease
• Individuals from countries with high TB rates
• Healthcare workers and others who work in high-risk settings
• People with weakened immune systems, including those with HIV/AIDS
• Residents and employees of high-risk congregate settings (e.g., correctional facilities, nursing homes)
• Individuals with certain medical conditions that increase TB risk

Choosing Between TST and IGRA: Factors to Consider

When deciding between a TST and an IGRA, several factors come into play. Which test is most appropriate for different situations?

Advantages of IGRA

IGRAs are preferred in certain circumstances:

• For people who have received the BCG vaccine, as it doesn’t cause false-positive results
• When it’s difficult for a person to return for TST reading
• In situations where a more specific test is needed

Considerations for TST

TST may be preferred when:

• Testing children under 5 years old
• In settings where IGRA is not available or is too costly
• For serial testing of healthcare workers or others at ongoing TB risk

Special Considerations in TB Testing

Certain populations require special attention when it comes to TB testing. What are some important considerations for these groups?

Testing in BCG-Vaccinated Individuals

People who have received the Bacille Calmette-Guerin (BCG) vaccine may have a positive TST result even if they’re not infected with TB. In these cases, an IGRA is often preferred as it’s not affected by prior BCG vaccination.

TB Testing in Pregnancy

Pregnant women can safely undergo both TST and IGRA tests. Testing is especially important for pregnant women at high risk for TB infection or progression to active disease.

Testing in HIV-Positive Individuals

People living with HIV should be tested for TB infection as they are at higher risk of developing active TB disease. Both TST and IGRA can be used, but interpretation may be affected by the degree of immunosuppression.

Frequency of TB Testing

How often should TB testing be performed? The frequency of TB testing depends on an individual’s risk factors and local guidelines. Some general recommendations include:

• Annual testing for healthcare workers and others in high-risk occupations
• Testing after known exposure to someone with active TB disease
• Periodic testing for individuals with ongoing TB risk factors

It’s important to note that there’s generally no problem with repeated TSTs or IGRAs, except in cases where a person has had a severe reaction to a previous TST.

Beyond Testing: Next Steps and TB Prevention

What happens after a positive TB test result? A positive TB test result doesn’t necessarily mean a person has active TB disease. Further evaluation is needed, which may include:

• A thorough medical history and physical examination
• Chest X-ray
• Sputum tests to check for TB bacteria

If latent TB infection is diagnosed, preventive treatment may be recommended to reduce the risk of developing active TB disease. For those with active TB disease, a comprehensive treatment plan will be developed, typically involving a combination of antibiotics taken over several months.

TB Prevention Strategies

Preventing TB transmission is crucial in controlling the spread of the disease. Key prevention strategies include:

• Early detection and treatment of active TB cases
• Treatment of latent TB infection in high-risk individuals
• Implementing infection control measures in healthcare and other high-risk settings
• Education and awareness programs about TB transmission and prevention
• Vaccination with BCG in countries with high TB prevalence

By combining effective testing, treatment, and prevention strategies, we can work towards reducing the global burden of tuberculosis and protecting public health.

Advancements in TB Diagnostics and Future Directions

The field of TB diagnostics is continuously evolving, with researchers working on developing more accurate, rapid, and accessible testing methods. What are some of the recent advancements and future directions in TB diagnostics?

Molecular Testing

Nucleic acid amplification tests (NAATs) can detect TB bacteria directly in sputum samples, providing faster results than traditional culture methods. The Xpert MTB/RIF assay, for example, can detect both TB and rifampicin resistance in about two hours.

Point-of-Care Testing

Researchers are developing portable, easy-to-use TB tests that can be performed in remote or resource-limited settings. These point-of-care tests aim to provide rapid results without the need for sophisticated laboratory equipment.

Biomarker Discovery

Scientists are exploring various biomarkers that could indicate TB infection or disease. These may include proteins, metabolites, or gene expression patterns that could lead to more sensitive and specific TB tests.

Artificial Intelligence in TB Diagnosis

Machine learning algorithms are being developed to interpret chest X-rays and other imaging studies, potentially improving the accuracy and speed of TB diagnosis.

As these new technologies emerge, they have the potential to revolutionize TB testing and diagnosis, particularly in high-burden, resource-limited settings where rapid, accurate diagnosis is crucial for controlling the spread of TB.

Global Efforts in TB Control and Elimination

Tuberculosis remains a significant global health challenge, with millions of people affected worldwide. How are global health organizations addressing this issue?

WHO End TB Strategy

The World Health Organization (WHO) has developed the End TB Strategy, which aims to end the global TB epidemic by 2035. Key components of this strategy include:

• Integrated, patient-centered care and prevention
• Bold policies and supportive systems
• Intensified research and innovation

Global Fund to Fight AIDS, Tuberculosis and Malaria

This international financing organization provides substantial funding for TB prevention, diagnosis, and treatment programs in low- and middle-income countries.

Stop TB Partnership

This global partnership works to coordinate and drive progress in TB elimination efforts worldwide, bringing together over 1,700 partners across 100 countries.

These global initiatives emphasize the importance of comprehensive approaches to TB control, including improved diagnostics, treatment access, and prevention strategies. By combining efforts at local, national, and international levels, the goal of TB elimination becomes more achievable.

The Role of Public Health in TB Control

Public health agencies play a crucial role in TB control and prevention. What are some key functions of public health in managing TB?

Surveillance and Monitoring

Public health departments track TB cases and trends, helping to identify outbreaks and high-risk populations.

Contact Tracing

When a TB case is identified, public health workers investigate to find and test close contacts who may have been exposed.

Directly Observed Therapy (DOT)

Many public health programs offer DOT, where healthcare workers observe patients taking their TB medications to ensure adherence and prevent the development of drug-resistant TB.

Education and Outreach

Public health agencies provide education to healthcare providers, high-risk groups, and the general public about TB prevention, symptoms, and the importance of testing and treatment.

Policy Development

Public health officials work with policymakers to develop and implement effective TB control strategies and guidelines.

By fulfilling these roles, public health agencies contribute significantly to TB control efforts, helping to reduce the burden of TB in communities and support global elimination goals.

Testing for Tuberculosis (TB) | TB

Tuberculosis (TB) is a disease that is spread through the air from one person to another. When someone who is sick with TB coughs, speaks, laughs, sings, or sneezes, people nearby may breathe TB bacteria into their lungs. TB usually attacks the lungs, but can also attack other parts of the body, such as the brain, spine, or kidneys.

TB bacteria can live in the body without making a person sick. This is called latent TB infection. People with latent TB infection do not feel sick, do not have TB symptoms, and cannot spread TB bacteria to others. Some people with latent TB infection go on to develop TB disease. People with TB disease can spread the bacteria to others, feel sick, and can have symptoms including fever, night sweats, cough, and weight loss.

There are two kinds of tests that are used to determine if a person has been infected with TB bacteria: the tuberculin skin test and TB blood tests.

Tuberculin Skin Test (TST)

What is a TST?

The Mantoux tuberculin skin test is a test to check if a person has been infected with TB bacteria.

How does the TST work?

Using a small needle, a health care provider injects a liquid (called tuberculin) into the skin of the lower part of the arm. When injected, a small, pale bump will appear. This is different from a Bacille Calmette-Guerin (BCG) shot (a TB vaccine that many people living outside of the United States receive).

The person given the TST must return within 2 or 3 days to have a trained health care worker look for a reaction on the arm where the liquid was injected. The health care worker will look for a raised, hard area or swelling, and if present, measure its size using a ruler. Redness by itself is not considered part of the reaction.

What does a positive TST result mean?

The TST result depends on the size of the raised, hard area or swelling. It also depends on the person’s risk of being infected with TB bacteria and the progression to TB disease if infected.

• Positive TST: This means the person’s body was infected with TB bacteria. Additional tests are needed to determine if the person has latent TB infection or TB disease. A health care worker will then provide treatment as needed.
• Negative TST: This means the person’s body did not react to the test, and that latent TB infection or TB disease is not likely.

Who can receive a TST?

Almost everyone can receive a TST, including infants, children, pregnant women, people living with HIV, and people who have had a BCG shot. People who had a severe reaction to a previous TST should not receive another TST.

How often can a TST be given?

Usually, there is no problem with repeated TSTs unless a person has had a severe reaction to a previous TST.

Testing for TB in People with a BCG

People who have had a previous BCG shot may receive a TST. In some people, the BCG shot may cause a positive TST when they are not infected with TB bacteria. If a TST is positive, additional tests are needed.

TB Blood Tests

What is an Interferon Gamma Release Assay (IGRA)?

An IGRA is a blood test that can determine if a person has been infected with TB bacteria. An IGRA measures how strong a person’s immune system reacts to TB bacteria by testing the person’s blood in a laboratory. Two IGRAs are approved by the U.S. Food and Drug Administration (FDA) and are available in the United States:

1. QuantiFERON®–TB Gold In-Tube test (QFT–GIT)
2. T–SPOT®.TB test (T–Spot)

How does the IGRA work?

Blood is collected into special tubes using a needle. The blood is delivered to a laboratory as directed by the IGRA test instructions. The laboratory runs the test and reports the results to the health care provider.

What does a positive IGRA result mean?

• Positive IGRA: This means that the person has been infected with TB bacteria. Additional tests are needed to determine if the person has latent TB infection or TB disease. A health care worker will then provide treatment as needed.
• Negative IGRA: This means that the person’s blood did not react to the test and that latent TB infection or TB disease is not likely.

Who can receive an IGRA?

Anyone can have an IGRA in place of a TST. This can be for any situation where a TST is recommended. In general, a person should have either a TST or an IGRA, but not both. There are rare exceptions when results from both tests may be useful in deciding whether a person has been infected with TB. IGRAs are the preferred method of TB infection testing for the following:

• People who have received the BCG shot
• People who have a difficult time returning for a second appointment to look at the TST after the test was given

How often can an IGRA be given?

There is no problem with repeated IGRAs.

Who Should Get Tested for TB?

The Centers for Disease Control and Prevention (CDC) and the United States Preventive Services Task Force (USPSTF) recommend testing populations that are at increased risk for TB infection. Certain people should be tested for TB bacteria because they are more likely to get TB disease, including:

• People who have spent time with someone who has TB disease
• People with HIV infection or another medical problem that weakens the immune system
• People who have symptoms of TB disease (fever, night sweats, cough, and weight loss)
• People from a country where TB disease is common (most countries in Latin America, the Caribbean, Africa, Asia, Eastern Europe, and Russia)
• People who live or work somewhere in the United States where TB disease is more common (homeless shelters, prison or jails, or some nursing homes)
• People who use illegal drugs

Choosing a TB Test

Choosing which TB test to use should be done by the person’s health care provider. Factors in selecting which test to use include the reason for testing, test availability, and cost. Generally, it is not recommended to test a person with both a TST and an IGRA.

Diagnosis of Latent TB Infection or TB Disease

If a person is found to be infected with TB bacteria, other tests are needed to see if the person has TB disease. TB disease can be diagnosed by medical history, physical examination, chest x-ray, and other laboratory tests. TB disease is treated by taking several drugs as recommended by a health care provider.

If a person does not have TB disease, but has TB bacteria in the body, then latent TB infection is diagnosed. The decision about taking treatment for latent TB infection will be based on a person’s chances of developing TB disease.

Related Links

• CDC Tuberculosis (TB)
• Basic TB Information

Tuberculosis (TB) Blood Test (IGRA)

On this page:
What is a TB blood test?
You should have TB blood (or TB skin test) if you:
How can I get a TB blood test?
What if my TB blood is “negative”?
What if my TB blood is “positive”?
What is latent TB infection?
What if I’ve had the BCG vaccine?

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What is a TB blood test?

The tuberculosis (TB) blood test, also called an Interferon Gamma Release Assay or IGRA, is a way to find out if you have TB germs in your body. The TB blood test can be done instead of a TB skin test (Mantoux).

There are two kinds of TB blood tests:

• QuantiFERON®-TB
• T-SPOT®.TB

You should have a TB blood (or TB skin test) if you:

• have had frequent close contact with someone who has active TB disease,
• have lived in a country where many people have TB,
• work or live in a nursing home, clinic, hospital, prison, or homeless shelter, or
• have HIV infection or your immune system is not very strong.

Children less than 2 years old should have the TB skin test instead of the TB blood test.

How can I get a TB blood test?

Ask your health care provider. They will draw a small amount of blood and send it to a laboratory. Your health care provider should tell you if your test result is “negative” or “positive” in a few days.

What if my TB blood is “negative”?

A “negative” TB blood test result usually means that you don’t have TB germs in your body.

What if my TB blood is “positive”?

A “positive” TB blood test result means you probably have TB germs in your body. Most people with a positive TB blood test have latent TB infection. To be sure, your doctor will examine you and do a chest x-ray. You may need other tests to see if you have latent TB infection or active TB disease.

What is latent TB infection?

There are two phases of TB. Both phases can be treated with medicine.

When TB germs enter your body, they cause latent TB infection. Without treatment, latent TB infection can become active TB disease.

Phase 1 – Latent TB Infection	Phase 2 – Active TB Disease
TB germs are “asleep” in your body. This phase can last for a very long time – even many years.	TB germs are active and spreading. They are damaging tissue in your body.
You don’t look or feel sick. Your chest x-ray is usually normal.	You usually feel sick. Your doctor will do special tests to find where TB is harming your body.
You can’t spread TB to other people.	If the TB germs are in your lungs, you can spread TB to other people by coughing, sneezing, talking, or singing.
Usually treated by taking one medicine for 9 months.	Treated by taking 3 or 4 TB medicines for at least 6 months.

What if I’ve had the BCG vaccine?

The BCG vaccine (TB vaccine) may help protect young children from getting very sick with TB. This protection goes away as people get older. People who have had BCG vaccine still can get latent TB infection and active TB disease.

If you had the BCG vaccine and you have a choice of having a TB blood test or a TB skin test, it is better for you to have the TB blood test. This is because the TB blood test is not affected by the BCG vaccine. This means that your TB blood test will be “positive” only if you have TB germs in your body.

Protect your health and the health of your family – get a TB blood test!

T-SPOT.TB – indications, preparation, benefits of the TB test

+7 (495) 276 08 08

Diagnosis of latent and active TB infection by T-SPOT.TB

T-SPOT

Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis (Koch’s rods). The infection mainly affects the lung tissue, but can spread to other organs. Tuberculosis does not go away on its own. To cope with the disease, timely diagnosis and high-quality treatment are necessary.

Tuberculosis is rarely talked about outside the medical community. There are many myths around this disease. The main one is that tuberculosis is an extremely rare, almost extinct infection. In fact, in many countries, including Russia, there is now an epidemic of tuberculosis, and every fourth carrier of a latent infection. At any moment, the latent form can turn into an open one, and the person will become dangerous to others. At the same time, in a latent form, tuberculosis can go unnoticed for many years, it does not cause symptoms and does not affect well-being.

Most methods for diagnosing tuberculosis do not allow detecting an infection in a latent form. The most advanced and accurate analysis that detects latent and active tuberculosis at the same time is T-SPOT.

What is T-SPOT

T-SPOT is a progressive method for diagnosing tuberculosis. Unlike subcutaneous Mantoux and Diaskintest tests, the T-SPOT method excludes patient contact with tuberculin and Mycobacterium tuberculosis antigens, there is no need to provoke an immune response. All that is needed for T-SPOT analysis is a standard blood sample.

Benefits of the T-SPOT method:

How the T-SPOT method works

During the study, the number of T-lymphocytes that produce interferon-gamma is determined in a blood sample. Due to this, it is revealed if there is an immune response and if Mycobacterium tuberculosis is present in the body.
The principle of the test is also reflected in its name: the letter “T” means T-lymphocytes, based on the reaction of which the analysis itself is carried out. “SPOT” is translated as “spot” – it is formed during the reaction if an infection is detected.
Testing takes place “in vitro” – in vitro. Thanks to this, the test is completely safe, has no contraindications and cannot cause adverse reactions.

Who needs T-SPOT

How to prepare for analysis

Special preparation for the study is not required.

Blood sampling is carried out on an empty stomach or not earlier than 4 hours after a light meal. It is permissible to drink pure non-mineral and non-carbonated water. Tea, coffee, juice are prohibited. The day before, avoid overeating, physical activity and emotional overstrain.

IMPORTANT:

The Mantoux test does not affect the result of the ELISPOT test for the diagnosis of tuberculosis infection, so it can be performed independently of the test.

After the Diaskin test, this study can be carried out no earlier than 2 months later.

During acute respiratory infections, a non-specific reaction may occur that interferes with the evaluation of the result. Therefore, it is preferable to do the test no earlier than 1 month after recovery.

What to choose?

T-SPOT

Mantoux

Diaskintest

Quantiferon test

At the moment, there are 4 main methods for diagnosing tuberculosis:

1. Two skin tests (Mantoux, Diaskintest)

2. Two laboratory blood tests (T-SPOT, Quantiferon test).

Of all the methods, T-SPOT is considered the most modern and accurate.
The specificity and sensitivity of the technique is 99%.
For the Mantoux test, these figures vary in the region of 70–80%.

Comparison of methods for diagnosing tuberculosis

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Tuberculosis and COVID-19

About 25% of the world’s inhabitants are infected with tuberculosis infection.
Most of those infected will be lucky and never know about it.
But you need to remember that the infection can wake up at any time – usually this happens against the background of reduced immunity.

The state of immunity is affected by chronic diseases, autoimmune and oncological processes, heavy therapy, and taking a number of medications. A separate group of people who are at risk for tuberculosis are HIV-infected. Russia has been experiencing an HIV epidemic for many years.

But HIV is not the only virus that destroys the immune system and makes the body defenseless against Mycobacterium tuberculosis. Since the beginning of 2020, the world has been living in a new coronavirus epidemic caused by the Sars-Cov-2 strain.

COVID-19 affects the lungs, and its complications have devastating effects on the cardiovascular system, liver, and other organs. Coronavirus weakens the body and reduces the defenses of the immune system. During the course of a coronavirus infection and a long recovery period after it, a person becomes especially vulnerable to tuberculosis. If the patient was a carrier of a latent form of tuberculosis, the risk increases that it will go into the active stage.

Despite all the efforts of the medical community and the development of medicine, tuberculosis is still among the ten leading causes of death in the world. Among infectious diseases, it ranks first, even ahead of HIV and coronavirus. Tuberculosis kills about 1.5 million people every year. About 10 million more are infected with tuberculosis each year.

Against the background of the coronavirus epidemic, WHO expects an increase in mortality from tuberculosis. People with tuberculosis, even in latent form, are more susceptible to contracting the coronavirus. Conversely, those who recovered from COVID-19are at risk for tuberculosis. A particularly difficult task for doctors is the simultaneous infection with coronavirus and tuberculosis, which is also not excluded.

Due to the similarity of the symptoms of coronavirus and tuberculosis, parallel diagnostics of these two diseases can be recommended, which will make it possible to make an accurate and complete diagnosis and prevent the spread of infections. Testing for tuberculosis after a coronavirus infection is also recommended.

The service can be used at the CITILAB medical center or at home.

Tuberculosis testing: which method to choose?

Mantoux reaction, Diaskin test, quantiferon test, T-spot, PCR, or maybe fluorography? Let’s tell you more.

Tuberculosis in Russia is so widespread that by the age of forty 70-90% of the inhabitants of our country are infected with it. This does not mean that they are sick: after infection, the immune system of most people copes with the bacterium. The probability of getting sick is on average 8% in the first two years after infection, then it gradually decreases, and acquired cellular immunity is formed. Among adults, people who are weakened, living in poor conditions, with a lack of light and fresh air, are more likely to get sick. However, absolutely anyone of us can get infected. That’s why it’s so important to get regular TB checks and check your kids.

IMPORTANT! Information from the article cannot be used for self-diagnosis and self-treatment! Only a doctor can prescribe the necessary examinations, establish a diagnosis and draw up a treatment plan for a consultation!

Why is the BCG vaccine needed?

WHO recommends mass vaccination of newborns against tuberculosis in all countries where the disease is prevalent. Therefore, on the 3-5th day after birth, even in the maternity hospital, all newborns are vaccinated with BCG free of charge. But this vaccine does not protect against TB infection. Her task is somewhat different. If an unvaccinated child younger than 2 years of age is infected with TB, they are very likely to develop TB meningitis and generalized forms of TB, which can lead to death very quickly. BCG quite reliably protects the child from these forms. It also protects children from pulmonary TB, but less effectively.

What other vaccinations do children under 2 years of age need?

Mantoux test

Mantoux test is performed annually for all children up to 7 years of age. This is not a vaccination (!), but an immunological test that shows whether there is a causative agent of tuberculosis in the body. In this case, tuberculin is injected intradermally – a specific protein containing antigens of human and bovine tuberculosis. After 72 hours, the size of the papule is measured. The result of the Mantoux reaction can be affected by visiting the sauna, taking a long bath, swimming in the pool and scratching the injection site. Temporary contact with water does not affect the results of the Mantoux test in any way, so the opinion that Mantoux cannot be wetted is a myth.

Diaskintest test

It is carried out for children from 8 years old. It is also a skin test. But if antigens of both human and bovine tuberculosis are used in Mantoux, then only antigens of human tuberculosis are used in diaskintest. Diaskintest is much more specific: a reaction to it occurs only if there are active tuberculosis bacteria in the body. Simply put, if the Mantoux test is positive, it still does not mean anything: this test often gives false positive reactions. But after the diaskintest, a reaction appeared – this is a more serious indicator.

The accuracy of Mantoux is 50-70%, Diaskintest is 90%.

Quantiferon test

Quantiferon test is one of the new methods for diagnosing tuberculosis by blood test. It is based on the determination of gamma-interferon in the blood, which cells produce in response to the introduction of a tubercle bacillus. Unlike Mantoux and Diaskintest, the quantiferon test does not require the introduction of any antigens and bacteria into the body. Blood for research is taken from a vein. The result is ready in a few days, and its accuracy is much higher than that of skin tests. The test will only be positive if the person is really sick.

T.SPOT.TB (“tee-spot”)

This method of diagnosing tuberculosis by blood is similar to the quantiferon test. The difference is that the quantiferon test detects gamma-interferon in the blood, which is produced in response to the introduction of a tubercle bacillus, and T-POTS determines the T-cells themselves, which produce gamma-interferon in the presence of Mycobacterium tuberculosis. Both tests are equally sensitive and informative (up to 97%), they are more sensitive than diaskintest and much more sensitive than the Mantoux reaction. “Te-spot” virtually eliminates false positive and false negative reactions, while the quantiferon test can still give a false positive reaction if, for example, a person was sick with ARVI at the time of blood donation.

Comparative characteristics of four tuberculosis tests

9 0088 No

	Mantoux	Diaskintest	Kwan tiferon test	T. SPOT.TB
Precision	50, 00%	90.00%	97.00%	97.00%
Evaluation of data	Subjective	Subjective	Objective	Objective
False positives	Common	Rare	Extremely rare
With latent form of tuberculosis	Not reliable	Not reliable	Reliable	Reliable
Contraindications	Many	Yes	No	No
With HIV and other immunodeficiencies	Not informative	Not informative	Informative	Informative
Test method	Skin test	Skin test	Blood test	Blood test

PCR

To distinguish between active and latent tuberculosis, a specific test is used – PCR (sputum DNA testing).