Tuberculosis (TB) General Information for the Public

Tuberculosis (TB) is a serious disease that affects people all over the world. TB used to be one of the leading causes of death in the United States, but not anymore.  In most cases, tuberculosis is preventable, treatable, and curable.

TB is caused by a tiny germ, a bacterium called Mycobacterium tuberculosis. TB usually affects the lungs, but it sometimes harms other parts of the body, like the brain, kidneys, lymph nodes, or spine. Common symptoms of TB include weakness, fever, weight loss, night sweats, chest pain, and a cough (sometimes a bloody cough) that won’t go away. Thanks to the knowledge and medications we have today, TB can be cured.  If left untreated though, TB disease can lead to disability and death.

Did you know San Mateo County has a TB Control Program?

The County’s TB Control program works hard to prevent tuberculosis, control its spread, cure people with TB disease, and protect the health of the public. Here are some of the things the TB Control Program does to prevent and control TB in our county:

  • We evaluate, treat, and provide case-management services for County residents with active TB disease or latent (sleeping) TB infection
  • We identify, notify, and follow up with people we know have been in contact with someone who has active TB disease
  • We investigate outbreaks of TB
  • We collect and analyze data about TB cases in the County
  • We consult with medical providers about how to diagnose and treat TB
  • We educate the public about TB

Although the number of TB cases in the United States has been dropping over the past 20 years, San Mateo County still experiences a significant number of TB cases each year.

Where can I get tested for TB in San Mateo County?

  • You can ask your doctor for a TB skin test or blood test
  • You can visit one of the County Clinics that offer TB skin tests or TB blood tests

Do staff and children in school or childcare need to be tested for TB?

Here are 3 things you can do to reduce TB in San Mateo County

  1. Learn the symptoms of TB disease
  2. If you have symptoms (or are close to someone with symptoms), ask your healthcare provider about TB testing
  3. If you’re being treated for TB, take all your medicine, exactly as your doctor prescribed it. Early treatment with antibiotics cures TB disease, so it’s very important to follow your doctor’s instructions and take all your medicine.

To see how TB affects San Mateo County, take a look at our latest TB Annual Report and then join us in the fight to prevent and cure TB!


The best way to know if you have TB is to get a TB test.

There are two kinds of tests: a skin test and a blood test. Either test can tell if you’ve been infected by the TB germ.

If you’ve been infected, you might need other follow-up tests to tell whether you have active TB disease.

Symptoms of TB depend on which part of the body is affected. 

Most people with TB disease have a cough that won’t go away, feel weak or sick, lose weight, have fever, and have night sweats.  If you have any of these symptoms, contact your doctor right away.


TB disease occurs when the TB germs are active in a person’s body in large numbers.  People with TB disease usually feel sick, and have one or more symptoms of TB disease.  They may be infectious, which means they can pass the TB bacteria on to others. If it’s not treated, TB disease can cause serious disability and even death.  

TB infection is caused by the same germs, but it’s less serious. People with TB infection are not sick because they have fewer of the germs in their body, and the germs are latent (sleeping). People with TB infection are not contagious. That means they cannot spread the germs to others. People with TB infection can end up developing TB disease in the future, especially if they are in one of the high-risk groups listed below, under "Who gets TB disease?"  People with TB infection can take medicine to keep from developing TB disease.

This chart explains the differences between TB disease and TB infection.

Latent TB Infection 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 cannot 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 several TB medicines for at least 6 months.


Who gets TB disease?

If you have latent TB infection, you may never develop active TB disease.  The risk of developing TB disease is higher if you:

  • Have HIV infection
  • Have been infected with TB germs recently (in the last 2 years)
  • Have other health problems, like diabetes, that make it hard for your body to fight germs
  • Take medications that suppress your immune system
  • Use alcohol or misuse drugs
  • Don’t eat enough healthy food
  • Smoke cigarettes
  • Were not treated correctly for TB infection in the past
  • Are a child younger than 5

How is TB spread?

  • TB germs are spread from person to person through the air.
  • TB germs get into the air when a person with infectious TB disease of the lungs or throat coughs, sneezes, laughs, or sings.
  • TB is NOT spread by touching or sharing dishes.


For a TB skin test, a health care worker uses a small needle to put a small amount of testing material, called tuberculin, just under your skin — usually on the inside of your forearm. After you get the test, you must return in 48 to 72 hours (2 to 3 days) to have the skin examined by a healthcare professional.  The test must be read in person by a trained health care worker. 

The TB blood test — also called an Interferon Gamma Release Assay (IGRA) — draws a small amount of blood. Results are usually available in a few days.

Here are 3 important choices about getting tested for TB:

  1. You can ask your doctor for a TB skin test or blood test
  2. You can visit one of the County Clinics [PDF] that offer TB skin tests or blood tests
  3. If you have been notified about being in contact with someone who has active TB, the County Health System can help you get tested for TB, even if you don’t have a  a regular doctor

Local clinics offering TB skin test or TB blood test

San Mateo County outpatient clinics offering TB skin tests or blood tests
Note: this information is subject to change. Please confirm in advance with the clinic!
Daly City Clinic
380 90th Street, Daly City
(650) 301-8600
TST & QFT: Mon & Wed 8:45-11AM
$40 per test.

Daly City Youth Health Center
(ages 13-21 years only)
2780 Junipero Serra Boulevard, Daly City
(650) 985-7000
TST & QFT: Mon-Fri 9:30-11:30AM & 1-4PM, except Thurs mornings.
Eligibility: Medi-Cal/HPSM, ACE, CHDP.
New patients require physical to establish care.

South San Francisco Clinic
306 Spruce Avenue, South San Francisco
(650) 877-7070
TST & QFT: Mon-Fri 9-11AM & 1-3:30PM
Eligibility: Medi-Cal/HPSM, ACE, CHDP.
Insurance screening available on site.
Fair Oaks Health Center
2710 Middlefield Road, Redwood City
(650) 364-6010
QFT only: Mon-Fri 8AM-5PM
Eligibility: Registered patients only (subject to change). Call to inquire.
Sequoia Teen Wellness Center
(ages 12-21 years only)
200 James Avenue, Redwood City
(650) 366-2927
TST & QFT: Mon-Fri 8:30-10:30AM & 1-2:30PM
Eligibility: Medi-Cal/HPSM, ACE, CHDP.
If uninsured, call to screen for Gateway Program coverage.
$10 for TST, $45 for QFT.

San Mateo County Mobile Health Van
(Varies by day, time, and location)
(650) 573-2786
TST & QFT: Mon-Wed.
(No TSTs on Thurs or Fri before a Mon holiday.)
TST: $35 per test, $49 for two-step test
QFT: $110 per test ($75 + $35 consultation fee)


A positive TB skin test or blood test usually means that you have been infected with the TB germ.  It does not always mean that you have TB disease.

Other tests, such as x-rays or sputum samples may be needed to see if you have TB disease.

A TB negative skin test or a TB negative blood test usually means you are not infected – but not always.

It you were recently exposed to TB, it can take 2 to 8 weeks for your body to recognize the TB germ and show up positive in a TB test.

If you have a negative test but continue to have symptoms, you may need to be tested again.

It can be very scary to find out you have TB infection or TB disease. The good news is that both TB infection and TB disease can be treated and cured. It’s important to get all the required follow-up tests, follow your doctor’s advice, and be sure to take all your medicine, exactly as prescribed.

BCG is a vaccine that helps prevent severe complications of tuberculosis (TB), especially in children. BCG is not widely used in the United States, although it’s often given to babies and small children in other countries, where TB is more common. 

Even if you (or your child) got the BCG vaccine, it’s still possible to get latent (inactive) TB infection or active TB disease.

If you had the BCG vaccine and need a TB test, a blood test may be more accurate than a skin test.

FAQs about Latent TB Infection

Many people have what’s called latent or "sleeping" TB infection, which is also called LTBI. People with LTBI breathed in TB germs and got infected, but their body fought the bacteria and stopped them from spreading.  Many of these people never develop active TB disease.

People with latent (inactive) TB infection:

  • Have no symptoms
  • Don't feel sick
  • Cannot spread TB to others
  • Usually have a positive skin test reaction or positive TB blood test
  • May someday develop active TB disease if they do not get treatment for latent TB infection

In many people with latent TB infection, the TB bacteria stay inactive for a lifetime without causing disease. But in others — especially people who have weak immune systems — the bacteria wake up, become active, multiply, and cause TB disease.

People with LTBI are at higher risk of developing TB disease if they:

  • Have recently been infected with TB germs (in the last 2 years)
  • Have other health problems, like diabetes, that make it hard for the body to fight germs
  • Have HIV infection
  • Take medications that suppress the immune system
  • Use alcohol or misuse drugs
  • Are malnourished
  • Smoke cigarettes
  • Were not treated correctly for TB infection or disease in the past
  • Are less than 5 years of age

If the Public Health System informs you that you’ve had contact with someone with active TB disease, you should see your doctor or call Public Health to arrange for the necessary tests

There are two kinds of tests that can identify latent TB infection — a skin test and a blood test.

The skin test is fast and simple. A small needle injects testing material, called tuberculin, under the skin. After the injection, you must return in 48 to 72 hours (2 to 3 days) to have the test read by a healthcare professional. 

In some cases, a TB blood test is used instead of a skin test. The blood test measures how your immune system reacts to the germs that cause TB.

If you have a positive TB skin test or blood test, you may need other tests to determine whether you have active TB disease or latent (inactive) TB infection. An x-ray of your chest can show if your lungs have been damaged by TB.  You may also be asked to provide samples of sputum (phlegm, pronounced “flem”) from deep in your lungs.  These sputum samples will be tested in a laboratory to see if TB germs are in your lungs.

It’s important to know that if you have TB disease in your lungs or throat, you can pass it on to other people when you breathe, cough, speak, sing or sneeze. If you do pass the germ on to others, they can get sick, too. If tests show that you have active TB disease, you may have to be separated from other people at the beginning of your treatment, until lab tests show that you are no longer spreading TB germs.

There are medicines you can take to prevent you from getting active TB disease.

Isoniazid (INH) is one common medicine used to treat latent TB infection. INH kills the “sleeping” TB germs before they have a chance to wake up and make you sick.

Public Health will work with your doctor to make sure you're getting the right kind of medicine for your TB infection. 

No matter which medication is prescribed, it’s important that you take all of it, exactly as directed.  TB germs are strong, so it takes many months for the medicine to kill them. 

INH works best if you take it every day. Take your INH without food.  If you’re taking another kind of medication, your doctor or Public Health System will tell you when it’s best to take the medication. 

While you’re taking INH or other TB medications, you should check in with your healthcare provider as scheduled to make sure your treatment is going well.

TB medicines are usually safe, although some people may have side effects.  If you think you are having any side effects to your TB medicine, call or see your doctor right away.



If you choose not to take medicine for latent TB infection, you might get sick with active TB disease.

It’s very important to take your INH (or other TB medication) every day. If you miss too many days, the medicine might not work.

TB medicines are usually safe, although some people may have side effects.  If you think you are having any side effects to your TB medicine, call or see your doctor right away.

Here are some ways to help you remember to take your medicine:

  • Keep your pills in a place where you’ll see them every day – and be sure to store them safely, and out of reach of small children
  • Ask a family member or friend to remind you every day
  • Mark your calendar every day after you take your pill
  • Use a pill reminder box
  • Take your pill at the same time every day — for example, after you brush your teeth, before you eat breakfast, or just before you go to sleep
  • If you miss any days, write them down so you can tell your doctor or nurse at your next check-up

The medication kills the TB germs in your body before they have a chance to wake up and make you sick.

TB germs are much easier to kill while they’re still asleep.

Many people take TB medication every day without any problems, but there are a few things you should watch for:

  • Poor appetite, losing weight, or feeling tired for no reason
  • Nausea or vomiting. If you have nausea when you begin taking your pills, try eating a little food with your pill, or try taking it at bedtime. If you’re still nauseous after three days, call your doctor right away.
  • Pain in your abdomen
  • Dark urine (the color of strong tea)
  • Yellow skin or eyes
  • Skin rash or itching
  • Numbness or tingling in your hands or feet
  • Coughing for more than three weeks
  • Sweating at night  
  • Fever for longer than 3 days

If you have any of these problems, call your doctor right away - don’t wait for your next appointment.

Other important things to remember:

  • Drinking alcohol while you take TB medicine can hurt your liver. Don’t drink beer, wine, or liquor until you completely finish your LTBI treatment.
  • Be sure to tell your doctor if you are taking any other medicine or if you think you may be pregnant.

If you are moving to another state or city, contact your health care provider before you move. They can help make sure that you get your TB medicine after you move.

The BCG vaccine (a TB vaccine) can help keep young children from getting serious complications of TB. However, this protection goes away as people get older. People who were vaccinated with BCG can still get latent TB (inactive) infection and active TB disease.

If you had the BCG vaccine and you’re offered a choice between a TB blood test and a TB skin test, it’s a good idea to choose the 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.

If you’ve had the BCG vaccine and you don’t have the choice to get a TB blood test, you should still have the TB skin test.

FAQs about Active TB

If your tests show that you have active TB disease, here are three important facts you should know:

  • TB is a serious disease.
  • In most cases, it can be cured with the right treatment and medicine.
  • Some people with TB disease can spread it to other people.

Anyone can get TB. When someone with TB disease of the lungs or larynx (windpipe) coughs, sneezes, or talks, TB germs can be sprayed into the air. Anyone close by can breathe the germs into their lungs. You cannot get TB from shaking hands or from food, dishes, linens or other objects.

After the TB germs entered your lungs, they went to sleep. Sleeping (inactive) TB germs don’t hurt your body or make you sick. This kind of infection is called latent TB infection, or “LTBI,” and it can last for a short time or for many years.

When the germs finally woke up and started to multiply, you developed active TB disease and started feeling sick. It is possible to spread TB to others when you have active TB disease.  Remember, every person with TB disease was once a contact to a TB case.

You can probably spread TB to other people, but it depends.

If TB is in your lungs or larynx (windpipe), you must be careful to protect other people from your TB germs. If TB is in other parts of your body — and not in your lungs or larynx — you probably aren’t able to spread the germs to other people.

Ask your doctor or nurse whether your TB is contagious, which means it can spread to others. Your healthcare provider will tell you what you must do to protect other people.

In most cases, after you’ve been taking medicine for a few weeks and you’re feeling better, you can no longer spread TB germs. Your doctor and public health nurse will be doing tests to check and see if you are still contagious.  They will tell you when it’s safe for you to go back to work, school, or other activities.


It might take more than one test to tell if you have TB disease, which may include:

  • A TB skin test (mantoux or tuberculin skin test), or a TB blood test (an Interferon Gamma Release Assay, or IGRA)
  • A chest x-ray, which can tell whether the germs have hurt your lungs
  • Sputum (phlegm, pronounced "flem") culture tests, which can tell whether TB germs are growing in your lungs

TB disease usually affects your lungs, which is called pulmonary TB. TB can also hurt other parts of your body.

People with TB disease usually have one or more of these symptoms:

  • Coughing for 3 weeks or longer
  • Weight loss
  • Poor appetite
  • Sweating at night
  • Fever
  • Chills
  • Feeling tired or weak
  • Pain in the chest
  • Coughing up blood or brown-colored material

To get better, you should follow these important steps:

  • You need to see a doctor and take special TB medicines to kill the TB germs.
  • TB germs are strong and live a long time. You will feel better a few weeks after you start to take the TB medicines.  Even though you feel better, you must keep taking TB medicines for at least 6-9 months to make sure you kill all the TB germs.
  • It’s important to work with your public health nurse and see your doctor regularly until your TB treatment is finished. The doctor will do follow-up tests to make sure you’re getting better, to ask if you have any problems with your medicines, and to answer your questions.

TB medicines are usually safe, although some people may have side effects.

If you have any of these symptoms, call or see your doctor right away:

  • Vomiting or stomach pain
  • Poor appetite
  • Nausea
  • Yellow eyes or skin
  • Tingling fingers or toes
  • Tingling or numb mouth
  • Blurred vision or change in your vision
  • Ringing in your ears
  • Trouble hearing
  • Dizziness
  • Aching joints
  • Fever for more than 3 days
  • Skin rash
  • Bleeding or bruising easily

Be sure to take all of your TB medicine together at the same time every day.

Unless you are having any of the above symptoms, keep taking your TB medicines until your doctor tells you to stop.

Don’t drink beer, wine or liquor while taking TB medicines.

TB germs are very strong. If you don’t take all of your medicine correctly, you might become sick again and can spread TB to other people.

To be cured, you must take all of your medicines — exactly as your doctor tells you.

If you do not take your medicine correctly, the medicines could stop working.  If that happens, your TB could spread.  To cure TB, you may then have to take other medicines for an even longer time, to make sure all the TB germs are killed.

It's best to do it right the first time, so take all your medicine exactly as prescribed.

“DOT” stands for Directly Observed Therapy. It means a nurse or health care worker sees you every day while you take your TB medicine. This is the best way to make sure that you get all the medicine you need and that your treatment is working. If there is a problem with your medication it can be fixed right away.

Sometimes, patients worry that they’re on DOT because their doctor or nurse doesn’t trust them. That’s not true. DOT is used for all patients with active TB disease in San Mateo County, because it is a supportive program to help patients through a very long course of treatment.  DOT is used all over the world and has been proven to help patients complete TB treatment.

DOT is recommended for all patients with active TB disease by the Centers for Disease Control (CDC), as well as the California Department of Public Health. In fact, DOT is used all over the world, because it helps patients complete TB treatment and get cured.

Did you know?

  • Studies show that 86-90% of patients receiving DOT finish TB treatment, compared to 61% for those who take treatment on their own
  • DOT helps patients finish TB therapy as quickly as possible, without unnecessary treatment gaps
  • DOT helps prevent TB from spreading to others
  • DOT decreases the risk of drug-resistance resulting from inconsistent or incomplete treatment
  • DOT decreases the chances of treatment failure and relapse
  • DOT gives patients a chance to be better connected to their healthcare team

DOT cures TB!

If you have TB, ask your doctor for an HIV test. People with HIV can get very sick from TB. You may need different TB medicines if you have HIV.

Remember: TB can be cured!

To learn more about TB