Tuberculosis Control Branch

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Understanding Your Test Results

Positive symbol indicating abnormal result

Positive (abnormal result)

If your blood test result is positive, it means you have TB germs in your body. A doctor or healthcare provider should examine you. Most people with positive TB tests feel just fine and have no signs of illness, because they have latent (or “hidden”) TB infection. Latent TB infection means that your body is able to keep you from feeling sick right now, but TB germs in your body could make you sick in the future. When you are sick from TB germs, it is called TB disease. When you have TB disease, your illness may spread to family members and other people around you.

The TB vaccine (or “BCG vaccine”) does not affect your blood test result: a positive blood test means you have TB germs in your body. Even if you have had the BCG vaccine, you can still have latent TB infection or TB disease and should be examined by a doctor or healthcare professional.

If you test positive do not worry: there is medication that can help you.

See “Next Step” to learn what to do next.

Negative symbol indicating normal result

Negative (normal result)

If your blood test result is negative, it means you do not have TB germs in your body.

Talk to your doctor if you plan to travel to places where TB is common (this includes many countries in Asia, Africa, Latin American, Eastern Europe and Russia) or if you are around someone with TB disease.

Other Types of TB Tests

You may have had a different type of TB test, the TB skin test (also sometimes called the “PPD”). If so, talk to your doctor or healthcare provider about how to understand this test. If the skin test is positive, you may need to be examined by a doctor or healthcare provider.

Next Steps

A positive blood test could mean either latent TB infection or TB disease. Therefore, a doctor or healthcare provider should examine you. For help finding a doctor or healthcare provider, please contact your local health department (Local Health Services/Offices, https://www.cdph.ca.gov/pages/localhealthservicesandoffices.aspx) or a local Federally Qualified Health Center (Health Resources and Services Administration: Find a Health Center, https://findahealthcenter.hrsa.gov). See additional info in “Frequently Asked Questions” below.

Your doctor or healthcare provider may ask you how you are feeling and recommend that you get a chest x-ray to make sure you do not have TB disease. They may also suggest you take medication for latent TB infection. Take the medicine to protect yourself and your loved ones from getting sick in the future.

If you notice symptoms that could be TB disease (such as a cough that lasts more than 3 weeks, fever, or weight loss for no reason), speak to your doctor or healthcare provider as soon as possible, ideally within a few days. If you are very sick, you may need to visit an emergency room.

For more information, please see the CDC Diagnosing Latent TB Infection and Disease webpage.

Doctor holding medication bottle and pen while talking to a patient

Medication to prevent TB disease (latent TB treatment)

If your doctor tells you that you have latent TB infection, it is important that you take medication to stop the germs in your body from making you sick in the future. Even though you may not feel sick now, taking medications will prevent you from getting sick with TB disease, and will keep you from spreading germs to your family in the future.

It is a lot easier to treat latent TB infection than TB disease.

There are different medicines that can be taken to prevent TB disease. Your doctor or healthcare provider will help you decide which one is right for you. It is important that you complete all of your medication for it to keep you from getting sick.

Most people complete latent TB treatment within 3 or 4 months.

Taking your medication for latent TB infection

Before You Start Your Medication:

Review all of your current medications with your doctor or healthcare provider. This includes birth control pills, prescription medications, over-the-counter medications, herbal medications and vitamins.
Let your doctor know if you drink alcohol regularly. You may need to cut back or avoid alcohol until you complete treatment.

While You Are Taking Medication:

It is important to take all of your medication the way your doctor or healthcare provider recommends. If not, the TB germs may grow in your body and be harder to get rid of.
Serious side effects are rare, but if you experience any of these symptoms, call your doctor or healthcare provider:

nausea, vomiting, diarrhea, abdominal pain or stomach cramps
fever
rash or itching
yellow eyes or skin
less appetite or no appetite for food
severe tiredness or weakness
pain, tingling or numbness in your hands, feet or joints
feeling dizzy or lightheaded

You may have red- or orange-colored urine (pee) or tears. This is normal with certain medicines used for latent TB infection. It does not hurt your body and will go away once you finish taking the medicines.

After You Take Medication:

Talk to your doctor or healthcare provider to let them know you have finished your treatment
Great job! You have protected yourself, and your loved ones, from getting sick with TB in the future.

Frequently Asked Questions (FAQs)

Who should I contact if I do not have a doctor or healthcare provider and/or health insurance?

Please contact your local health department (Local Health Services/Offices; https://www.cdph.ca.gov/pages/localhealthservicesandoffices.aspx) or a local Federally Qualified Health Center (health care clinic) (Health Resources and Services Administration: Find a Health Center; https://findahealthcenter.hrsa.gov/) for more information about where you can get treated for latent TB infection. If you need additional help with insurance or getting an appointment, you may want to reach out to social service organizations in your county. Using an internet search engine, type in the name of the county you live in and the words 'social services'. This should bring up a link to your county's social services webpage, which includes information about healthcare access and how to apply for healthcare assistance programs like Medi-Cal.

Can I be fired from work, expelled from school, or forced to leave the country because I tested positive for TB?

Your test results will be kept confidential. The clinic or public health program is not allowed to share this information with anyone other than the healthcare providers that care for you. You cannot legally be fired from a job or forced to leave school or the country if you have latent TB infection.

I was born in another country and received the BCG vaccine. Is BCG causing my blood test to be positive?

No. Having a BCG vaccine does not cause a positive blood test. If your TB blood test is positive, then you most likely have TB infection. Learn more about BCG at: CDC Bacille Calmette-Guerin (BCG) Vaccine for Tuberculosis (https://www.cdc.gov/tb/hcp/vaccines/).

I was born in another country and received the BCG vaccine. Even thought I have a positive blood test, BCG will protect me against TB, right?

The BCG vaccine is given to people in some countries at an early age to protect against TB. Over time the vaccine stops providing protection, meaning most teenagers and adults are not protected by the vaccine. Even if you received BCG as a child, you should be seen by a doctor or healthcare provider, and you probably need treatment for latent TB infection or TB disease. Learn more about BCG at: CDC Bacille Calmette-Guerin (BCG) Vaccine for Tuberculosis (https://www.cdc.gov/tb/hcp/vaccines/).

Do I need to isolate (stay away) from others if I have a positive TB test?

People with a positive TB test but no symptoms of TB disease (such as cough for more than three weeks, fever, or weight loss without trying to lose weight) cannot usually spread TB and do not need to stay away from others. However, you should be examined by a doctor or healthcare provider and should receive a chest x-ray to make sure. Please contact your doctor or the local health department with additional questions about isolation.

Is there natural treatment to treat latent TB infection?

The TB medication that your doctor gives you is the only way to get rid of TB germs in your body. There are no other medicines, natural remedies or vitamins that are proven to get rid of TB germs.

I thought TB is genetic or inherited so how can it be prevented?

There are many myths about TB. Some people think it is inherited, and others believe it can be caught from drinking cups, forks/spoons/knives or touching someone with TB. In fact, TB can only be caught if you breathe in the germs when a person with TB disease coughs or speaks. The reason TB can be common in families is because families spend a lot of time together and breathe the same air: it is not genetic or inherited.

If I was treated for latent TB infection (or TB disease) in the past, and I have a positive test now, do I need to be treated again?

Treatment is generally not required more than once, but if you think you have been exposed to someone who was sick with TB disease, please contact your doctor or healthcare provider to see if you need more medical assistance. This is especially important for people with other health conditions, such as diabetes or cancer.

Doesn’t treating latent TB infection take a long time?

Killing all the TB germs in your body several months. It is much easier to treat latent TB infection than TB disease. Most treatments for latent TB infection last 3-4 months, compared to 6 months or longer for TB disease. This is why we recommend getting treated for latent TB, before the germs have a chance to grow in your body and make you sick.

How do I know that treatment for latent TB infection was successful?

There is no specific test to show that treatment was successful, but studies have shown that treatment for latent TB infection is very good at preventing TB disease. Taking medications for latent TB infection now gives you the best chance of preventing you from getting sick and from spreading germs to your family and friends.