TB Fact Sheet for Health Care Workers
What is tuberculosis?
Tuberculosis is an infection caused by a bacterium called mycobacterium tuberculosis. If the bacterium enters the lung, it can multiply and can cause disease. The disease it causes is tuberculosis, or TB. It affects the lungs and, sometimes, other parts of the body. People with tuberculosis suffer from cough, sputum (secretions from coughing), fever, night sweats and weight loss. Anytime people have a cough (especially with sputum) for longer than two weeks, they should see a health care provider for an examination.
Why are health care workers at risk for TB?
Tuberculosis is spread by the respiratory (throat or lung) secretions of people who have TB in their lungs. These secretions contain TB bacteria. If a person with tuberculosis is coughing and a shower of these droplets enters the air, anyone breathing that air may become infected. Health care workers may be exposed to the tuberculosis bacteria by taking care of patients with tuberculosis who have the bacteria in their sputum. They may also become exposed by coming in contact with friends or neighbors who have TB.
What happens if I am exposed to the TB bacteria?
TB is not as easily spread as, for example, measles or chicken pox. If a person is exposed to the TB bacteria, three things can happen:
- The person may not become infected at all.
- The person may become infected but not sick.
- The person may become sick with the disease.
Even if a person becomes infected, only 10 percent of people infected will actually get the disease "tuberculosis" that causes the cough, fever, weight loss and other symptoms mentioned above.
Most people who become infected with the tuberculosis bacteria develop what we call "latent infection" – not "active disease." People with latent infection will have a positive TB skin test but do not have any other signs of illness. They are not contagious and cannot give the infection to others. They do not feel sick and have no idea that they have become infected. They are not sick because their immune system (the system in the body that protects us from infections), is keeping the bacteria in check and not allowing them to grow and cause damage.
How does a TB skin test work?
A TB skin test is done by injecting a very small amount of a protein that contains certain parts of the tuberculosis bacteria. The test material itself cannot cause any infection, TB or otherwise. In addition, it is not a vaccine and will not protect you from getting TB. The test only determines if a person has a reaction to the skin test.
If a person has become infected with tuberculosis and has latent infection or active disease, their body will "recognize" these proteins and will react to them. This reaction will cause a small bump to appear under the skin where the test was applied. If the bump is of a certain size, we call this a positive test. If there is no bump or a very small bump, the test is considered negative. It takes about 10 weeks for a person's TB skin test to turn positive after infection with tuberculosis.
Even if a person is infected with tuberculosis, the test may, on rare occasions, still appear negative. This happens with people who have lost the ability to react to skin tests because of diseases such as HIV infection, certain medications or old age. This loss of response is called “anergy.”
What does it mean and what do I do if my TB skin test is read as positive?
If your skin test is read as positive, it would most likely mean that you are infected with the TB bacteria. If you are feeling well and not suffering from cough, fever or weight loss, you probably have latent infection, not active disease.
In order to make sure you do not have the actual disease, you will have an evaluation, which will include questions on how you are feeling, an exam of your chest and a chest X-ray. If the chest X-ray looks normal and you are not sick, you do not have the disease.
Remember, if you have latent TB infection, but not the disease, you cannot give the infection to others. This is because your body's defenses are preventing the bacteria from multiplying and growing.
Some people who have had the tuberculosis vaccine "BCG" will have a positive test even though the BCG was given in the remote past. That's because the body recognizes the PPD given in the skin test because it is similar to the BCG. There is a blood test that can separate positive skin test because of BCG from positive skin test because of TB infection. If you have had BCG in the past, we will do the blood test instead of the skin test. This blood test can also be done annually.
What can be done for a person with a positive skin test?
First, let's review what a positive test means. A positive test with a normal chest X-ray means latent infection.
Most people with latent infection will never develop active TB. However, there is a small chance that in the future their body's defenses will break down, and the bacteria will multiply and cause disease. This is called "reactivation." Certain factors make it more likely that reactivation will occur. In that case, people with a positive skin test may need to take medication to prevent the infection from becoming active sometime in the future.
Why do some people with latent infection get the disease?
Certain factors make a person more likely to reactivate, or go from latent infection to active disease.
One of the most important factors is when the person became infected. The chance of reactivating is highest during the first two years after getting the infection. This is why we give health care workers a skin test every year. If we know when the test went from negative to positive, we can figure out when the person came in contact with the bacteria and became infected.
Other factors that increase the chance of reactivation are:
- damage to the body's defenses as can occur with cancer
- medications such as steroids
- chemotherapy.
People with HIV disease or AIDS are at high risk for developing active TB if they are exposed to the bacteria and are going from latent to active disease. This is because HIV infection damages the immune system.
People with HIV infection or AIDS have a much greater chance of developing tuberculosis if they are exposed to the bacteria.
How does medication protect an infected person from getting disease?
In order to make sure that latent infection does not turn into active disease sometime in the future (reactivate), the person with a positive skin test can be given medication. This medication, Isoniazid, gets rid of the infection so that the bacteria cannot multiply and become active. The medication is given for 9 months. Isoniazid also is called isonicotinyl hydrazine or isonicotinic acid hydrazide and is often abbreviated INH.
We give the medication to people who are more likely to go from latent infection to active disease. These are people who were recently infected or have other medical conditions that make them less able to fight off the disease.
The Employee Health Service physician or occupational health nurses see all employees who have positive skin tests. If you need medication, they will let you know. They also will be happy to consult with your personal physician.
Can a person with the disease TB be cured with medication?
Yes. People with the active disease must take two or more medications for a period of 6-12 months. The medications will destroy the bacteria and remove the infection from the body.
Of course, in order to be effective, the TB bacteria must be able to be destroyed by the medication. Not all TB bacteria can be fought with every TB medication.
That is why we treat active disease with two or more drugs and conduct laboratory tests to make sure that the bacteria is being killed by the medication.
During the past few years, some people have come down with TB caused by TB bacteria that is very difficult to kill. Many of the medications we use to treat TB are not able to kill these bacteria. We call these bacteria "resistant" to medications. This type of TB is hard to treat and the patient must be followed closely to make sure the medication is working.
How can we protect health care workers from being infected with TB?
The most important way to decrease the chance of getting TB is to reduce the chance of coming into contact with the bacteria. We do this in three ways:
- We identify patients who may have active TB. Any inpatient or outpatient with symptoms of chronic cough, fever, weight loss or other TB symptoms should be evaluated for tuberculosis. If patients have TB, or if we suspect them of having TB, we must place them in TB isolation. This means placing them in a private room where the air is changed often to decrease the amount of TB bacteria. We make sure that the room is at negative pressure compared with the outside. This means that air will flow into the room but will not flow from the room to areas outside of the room, such as the hall or other common areas.
- If health care workers (or visitors) have to enter a TB isolation room, they must wear a mask or respirator. The type of mask chosen will filter out particles the size of the droplets containing TB bacteria and will not let the bacteria get into the lung. The mask must fit properly in order to be effective. Health care workers must be medically able to wear the mask and then must be fitted with the right size. They also must receive training on how to put on the mask, how to check for a proper fit and where to store the mask. If you need more information, please ask your supervisor or call Safety Management Services at 734-764-4427.
- Employees should have a TB screening each year. Employee Health Service will send your supervisor a notice when you are due to be tested. We test health care workers once a year so we can find people whose tests have turned positive and see whether any treatment is necessary. Treatment is most important for people infected within the last two years.
By doing annual TB screening, we will we be able to find people who were infected recently.
Where can I get more information regarding tuberculosis?
The Employee Health Service nurse is available to answer questions about the information provided here or to address other concerns regarding TB.
It is best to make an appointment to speak with the EHS nurse rather than coming in on a walk-in basis. An appointment will give you enough time to have all your questions answered and will assure that you will not have to wait long to be seen.
Call Employee Health Service at 734-764-8021 to set up an appointment. If your skin test is positive, an appointment will be set up for you. Your physician or local health department can also give you information regarding TB.
You can also visit the Centers for Disease Control and Prevention Web site.
CDC Fact Sheets about Tuberculosis:
