Tuberculosis (TB) is an infectious disease that affects millions of people worldwide. It is one of the ten leading causes of death worldwide, and its early diagnosis is essential for effective treatment and successful recovery. In the last decade, there has been a significant advance in the detection of tuberculosis, thanks to the introduction of blood tests for tuberculosis.
Blood Test for Tuberculosis: A new era in Diagnosis
The blood test for tuberculosis is a faster and more accurate way to diagnose the disease. Instead of looking for bacteria in sputum samples, these tests look for specific antibodies in the blood that indicate a tuberculosis infection. Blood test for tuberculosis are more accurate than sputum tests and can produce results in a matter of hours, rather than days or weeks.
For decades, tuberculosis screening has relied on the identification of bacteria in sputum samples, a process that can be lengthy and does not always produce accurate results. However, in the last decade, there has been a significant advance in the detection of tuberculosis, thanks to the introduction of a blood test for tuberculosis.
In addition to being more accurate and faster, blood test for tuberculosis are also easier to administer. Blood sampling is less invasive than sputum sampling, making it more acceptable to patients. They are also easier to administer in resource-limited health care settings, such as in developing countries, where tuberculosis is more prevalent.
Another advantage of blood test for tuberculosis is that they can detect both active and latent tuberculosis. Latent tuberculosis is a form of the disease in which the patient has no symptoms, but can still transmit the disease. Early detection of latent tuberculosis is important to prevent the spread of the disease.
What is an Interferon Gamma Release Assay (IGRA)?
An IGRA test is a blood test for tuberculosis that can determine if a person is infected with the bacteria. The IGRA test measures how responsive a person’s immune system is to the tuberculosis bacteria, using a laboratory blood test. There are two US Food and Drug Administration (FDA) approved IGRA tests available in some countries.
- QuantiFERON®-TB Gold Test in Tube (QFT-GIT)
- T–SPOT® Test for Tuberculosis (T–Spot)
How does the IGRA test work?
Blood test for tuberculosis it’s simple to do. With a needle, blood is drawn into special tubes. The blood is sent to a laboratory as indicated in the instructions for the IGRA test. The laboratory does the test and sends a report with the results to the health care provider.
What does it mean to have a positive IGRA test result?
- Positive IGRA test result: This means that the person’s body is infected with TB bacteria. More tests will need to be done to determine if the person has latent TB infection or TB disease. A healthcare worker will provide treatment as needed.
- Negative IGRA test result: This means that the person’s blood did not react to the test, and they are not likely to have latent TB infection or disease.
Who can take the IGRA test?
Everyone can get the IGRA test instead of the skin test. This can be done whenever a skin test is recommended. In general, people can get either the skin test or the IGRA test, but not both. There are rare exceptions in which it might be useful to have the results of both tests to decide if a person has TB infection.
The IGRA tuberculosis detection method is preferred in the following cases:
- People who have received the BCG vaccine
- People who have difficulty returning for the second appointment to look at skin test results
How often can the IGRA test be done?
There is no problem with repeating the IGRA test or blood test for tuberculosis.
Who should be tested for tuberculosis?
People who are at low risk of becoming infected with TB bacteria usually do not need to be screened.
Certain people should have this test because they are at higher risk for this disease, including:
- People who have been with someone who has TB disease.
- People with HIV infection or another medical problem that weakens their immune system.
- Poblation who have symptoms of tuberculosis disease (fever, night sweats, cough, and weight loss).
- People who come from a country where tuberculosis is common (most countries in Latin America and the Caribbean, Africa, Asia, Eastern Europe, and Russia).
- People who live or work in a place in the United States where TB disease is more common (homeless shelters, prisons or jails, or nursing homes).
- Person who use illegal drugs.
We do not know if it is entirely advisable for a person with HIV to have a blood test for tuberculosis, which is why they should have better prevention.
In addition, tuberculosis is one of the leading causes of death in people with HIV. Therefore, it is important that infected people are regularly tested for tuberculosis, and receive preventive treatment, if necessary. It is also important that people living with HIV take steps to protect their health and prevent TB infection, such as maintaining good hygiene, avoiding close contact with people who are sick, and following their doctor’s advice.
How to choose a tuberculosis screening test?
It is up to the health care provider to choose which tuberculosis screening test to give the person. Factors that determine which test to use include the reason for the test, the availability of the test, and the cost. In general, it is not recommended to give a person the two tests: the skin test and the IGRA test or blood test for tuberculosis.
Diagnosis of latent tuberculosis infection or tuberculosis disease
If a person is found to be infected with tuberculosis bacteria, more tests will need to be done to see if he has tuberculosis disease.
Tuberculosis disease can be diagnosed with a medical history, physical examination, chest X-ray, and other laboratory tests. It is treated by taking various medications as recommended by the health care provider.
If a person does not have TB disease, but does have TB bacteria in their body, then latent TB infection is diagnosed. The decision about treatment for latent TB infection will be based on the chances that the person will get TB.
In summary, blood test for tuberculosis are an important tool for early and accurate diagnosis of the disease. Their use can improve the effectiveness of treatment, reduce the spread of disease, and improve health outcomes for patients. Over time, blood tests for tuberculosis are expected to play an increasingly important role in the detection and control of the disease worldwide.
How is tuberculosis in children treated?
There are two situations in which children should receive TB treatment. These are:
- TB disease treatment for children who are sick with tuberculosis
- Latent TB treatment for children to prevent them from developing tuberculosis.
Just as TB treatment is given to adults, TB treatment for children involves several months of taking several different drugs at the same time. Now there is an improved treatment for children that is easier on the child. This will usually include four medications adjusted for the child’s weight.
Tuberculosis prevention begins with awareness and education.
