Intercountry (International) Adoption: Tuberculosis

About TB

TB is caused by a bacterium called Mycobacterium tuberculosis that spreads through the air from one person to another when a person with TB disease of the lungs or throat coughs, speaks, or sings. The bacteria usually attack the lungs, but TB bacteria can attack any part of the body such as the kidneys, spine, and brain.

TB disease is a serious condition. Worldwide, approximately 1.3 million people died of TB in 2022, including 167,000 people with HIV. In the United States, TB disease is less common than in many other countries. In 2022, the United States reported 8,331 TB cases. Learn more about tuberculosis in the United States at CDC's Tuberculosis Data and Statistics webpage.

TB Testing and Diagnosis

As required by U.S. law, any child or adult who is applying for an immigrant visa to enter the United States needs an overseas medical exam, which includes testing for TB. This medical exam must be conducted by a panel physician, a doctor who has an agreement with the local U.S. embassy or consulate to perform the exam according to requirements described in the Technical Instructions written by the CDC.

There are two kinds of tests used to detect TB bacteria in the body (TB infection):

1. TB skin test (TST)
2. TB blood tests (including IGRA)

A positive TB skin test or TB blood test means that a person has been infected with TB bacteria. It does not tell whether the person has LTBI or TB disease. Other tests, such as a chest x-ray and sputum samples are needed to see whether the person has LTBI or TB disease. More information on TB diagnosis can be found in the next section of this page and on CDC’s TB Testing webpage.

According to CDC's Technical Instructions, several factors affect the choice of TB tests for a child. These include:

• The child's age
• Whether the child has
  • Known HIV infection
  • TB signs or symptoms, or
  • A personal history of TB disease
• Whether the child is is undergoing the panel physician examination in a country with a high TB disease rate, defined as ≥ 20 (20 or more) TB cases per 100,000 people, as estimated by the World Health Organization (WHO).
• Whether the child is a known contact of a person with TB disease (for example, lived in the same house with that person)

Types of TB Tests

Interferon-Gamma Release Assay (IGRA)

• This is a blood test conducted to detect and measure a child’s immune response to TB bacteria. It can have a positive result because of LTBI or TB disease.
• Children 2 years of age and older examined in countries with a WHO-estimated tuberculosis disease rate of 20 or more cases per 100,000 people must have an IGRA. In these countries, IGRA can also be performed for children younger than 2 years of age with known HIV infection or TB signs or symptoms, but TST is an option for children younger than 2 years of age who need to be tested for TB infection.
• In countries with a TB disease rate fewer than 20 TB cases per 100,000 people, an IGRA is required in any child younger than 15 years old with known HIV infection or TB signs or symptoms.
• Children who are a known recent contact of a person with TB disease also need an IGRA performed.
• If your child has a positive IGRA result, your child will need a chest x-ray to help determine if your child has LTBI or TB disease.
• Children with HIV infection are less likely to have a positive IGRA, even if they have TB disease, so children with known HIV infection must have a chest x-ray and provide three sputum specimens for smears and culture plus molecular testing of the first sample, regardless of IGRA result, to ensure they do not have TB disease.
• Children who have signs or symptoms of TB disease must also have a chest x-ray and provide three sputum specimens for smears and culture plus molecular testing of the first sample, regardless of IGRA result, to ensure they do not have TB disease.

Tuberculin Skin Test (TST)

A TST is performed only if the child is younger than 2 years of age and has known HIV infection or TB signs or symptoms or is a known recent contact of a person with TB disease, or if an IGRA is not available. Like the IGRA, a TST is used to determine if your child has an immune response to TB. A TST can have a positive result because of LTBI or TB disease.

• The test is performed by a healthcare worker, who injects a small amount of fluid (called tuberculin) just under the top layer of the skin of your child’s lower arm.
• After 48-72 hours, your child returns to the healthcare worker, who looks for a raised, hard area or swelling at and around the injection site. A raised area measuring 10 millimeters or more is a positive TST result (TST measuring 5 mm or more is a positive test if your child has known HIV infection or is a known recent contact to a person with TB disease).
• If your child has a positive TST result, your child will need a chest x-ray to help determine if your child has LTBI or TB disease.
• Children who have known HIV infection or signs or symptoms of TB disease must have a chest x-ray and provide three sputum specimens for smears and culture plus molecular testing of the first sample, regardless of TST result, to ensure they do not have TB disease.

Chest X-ray

This is an x-ray of your child’s lungs that is performed if your child has a positive IGRA or TST, known HIV infection, TB signs or symptoms, or a personal history of TB disease.

• Children with HIV infection are less likely to have a positive chest X-ray, even if they have TB disease. Therefore, children with known HIV infection must provide three sputum specimens for smears and culture plus molecular testing of the first sample, regardless of chest X-ray findings, to ensure they do not have TB disease.
• Children who have signs or symptoms of TB disease must also provide three sputum specimens for smears and culture plus molecular testing of the first sample, regardless of chest x-ray findings, to ensure they do not have TB disease.

Sputum Samples (3 total)

Sputum samples are needed if your child’s chest x-ray suggests TB disease, or if your child has known HIV infection, or TB signs or symptoms.

• Under the direct observation of a trained healthcare worker, your child produces three samples of sputum (mucus that is coughed up) that are collected and tested for TB bacteria. One sputum sample is collected per day on three separate days.
• If a child is unable to cough up enough sputum for testing, the panel physician will consider sputum induction, early morning gastric aspirates, or molecular testing of stool.
  • In sputum induction, your child is given an inhaler with saline solution (a mixture of salt and water) to help them cough up sputum. This can work well if your child is old enough to cooperate with directions.
  • In an early morning gastric aspirate, a tube is passed through your child’s nose into their stomach and used to collect lung mucus that your child has swallowed. This method can be very helpful if your child is unable to follow directions to cough, for example because of very young age or developmental disabilities.
  • A molecular test (a test that looks for DNA of the TB bacteria) performed on three stool specimens can be acceptable in place of gastric aspirates, in some circumstances. If a child has a positive stool test, three gastric aspirates must be collected to attempt to grow the TB bacteria.

Sputum Smear (3 total)

To confirm whether your child has TB disease, the sputum sample is processed, placed on a microscope slide, and examined for TB bacteria under a microscope. There are several types of bacteria that can resemble TB; therefore, a positive smear is only suggestive of TB. Because small amounts of TB bacteria can be missed under a microscope, a negative smear does not confirm that the child does not have TB disease.

Molecular Tests

Sputum Culture (3 total)

To confirm whether your child has TB disease, the sputum sample is processed, placed in a tube with growth nutrients, and kept in a lab for 8 weeks to watch for the growth of TB bacteria.

• Sputum culture is the most accurate laboratory test that doctors can use to determine whether your child has TB disease.
• If your child has TB disease, the bacteria should grow and be visible within 2 - 8 weeks, which means a positive diagnosis of TB disease. Because TB bacteria often grow slowly, a full 8 weeks must pass to allow the bacteria to grow.
• If your child does not have TB disease, no TB bacteria will grow by the end of 8 weeks. This is called a negative TB culture. However, sometimes, even if the laboratory tests are negative, if your child has persistent TB signs or symptoms, the doctor may make a clinical diagnosis of TB disease because not treating TB can have severe consequences.

Drug Susceptibility Test (DST)

If your child has a positive sputum culture, this laboratory test determines which medications can best kill the TB bacteria. Based on the results of this test, doctors will select the TB medications that will be most effective.

Typical Timeframe for TB Testing

Treatment Administration

TB disease is treated with a combination of antibiotics determined by your child’s strain of TB. A four-drug regimen is usually used to treat TB disease. If your child is receiving medication to treat TB disease, a healthcare worker or other trained person will watch your child swallow each dose of medication. This treatment is called directly observed therapy (DOT) and is the standard of care. TB treatment typically takes 6 months or more to complete.

If your child is diagnosed with LTBI, the panel physician may offer treatment but treatment of LTBI is not required for your child to immigrate to the United States. LTBI treatment is important to prevent progression to TB disease, especially in children. Your child can also be treated for LTBI after they move to the United States.

Learn more about the treatment of TB disease and LTBI at CDC’s Treating Tuberculosis and TB Treatment for Children webpages.

TB and HIV

TB disease is the leading cause of death among people with known HIV infection and one of the most common diseases for people with weakened immune systems. Therefore, it is especially important for people with known HIV infection to be tested for TB.

Because HIV infection weakens a person’s immune system, and some of the TB tests measure a person’s immune response to the TB bacteria, people with known HIV infection and TB may:

• Test negative on the IGRA or TST, chest x-ray, and sputum smears, BUT
• Test positive on the sputum culture.
  • Known HIV infection is not the only reason why your child's sputum smears may be negative but the sputum culture test is positive.

Therefore, to accurately determine whether people with known HIV infection have TB disease and to help them receive appropriate medical care as quickly as possible, they are required to undergo multiple tests.

If your child has known HIV infection, he or she must have an IGRA (or TST if younger than 2 years of age), a chest x-ray, and sputum smears and cultures. Some people with HIV infection and TB disease don’t have enough of an immune response for the IGRA or TST result to be positive or for TB disease to show on a chest x-ray; others will have positive tests or show TB disease in the lungs on x-ray. Therefore, sputum smears and cultures are useful for diagnosis in these children. For those who do show lung TB disease on their chest x-ray, the panel site radiologist can compare the chest x-ray taken before treatment with chest x-rays taken during and after treatment to help determine whether the medication your child is taking is effectively curing the TB disease.

Waivers and Exemptions

Waivers

Children who have TB disease and apply to immigrate to the United States are required to complete TB treatment before traveling to the United States. However, for children whose medical situations suggest they would benefit from receiving their TB treatment in the United States, the Department of Homeland Security’s U.S. Citizenship and Immigration Services may grant a Class A waiver allowing them to travel to the United States before the end of their TB treatment. More information on waivers can be found on the Intercountry (International) Adoption Health Guidance webpage.

Exemptions

Immigrant applicants (including children who have been adopted from other countries) older than age 10 cannot travel to the United States until sputum culture results are completed. However, applicants 10 years of age or younger who require sputum cultures, regardless of HIV infection status, may travel to the United States immediately after sputum smear analysis and molecular test results are reported as negative (while culture results are pending) if none of the following conditions exist:

• Chest X-ray that shows:
  • One or more cavities, or
  • Widespread TB disease in the lungs (especially in the upper area of the lung)
• A forceful and productive cough
• Known contact with a person with multidrug-resistant TB or extensively drug-resistant TB who could have spread TB bacteria at the time of contact

If the child could not provide sputum specimens and gastric aspirates were obtained, positive gastric aspirates for acid-fast bacillus (AFB) smears do not prevent travel while culture results are pending.

This exemption can occur only for applicants who are traveling immediately and can be seen by a U.S. healthcare provider within days of arrival in the United States.