Latent Tuberculosis Infection (LTBI) Fact Sheet (PDF)

Learn more about Oakland County Health Division TB treatment, screening and reporting here.

What is tuberculosis?

Tuberculosis (TB) is a disease caused by germs that are spread from person to person through the air. TB usually affects the lungs, but it can also affect other parts of the body, such as the brain, the kidneys, or the spine.

The general symptoms of TB disease include feelings of sickness or weakness, weight loss, fever, and night sweats. The symptoms of TB disease of the lungs also include coughing, chest pain, and coughing up of blood. Symptoms of TB disease in other parts of the body depend on the area affected.

How is tuberculosis spread?

The germ is spread through the air when a person with active lung disease coughs, sneezes, speaks or sings. It can be inhaled by someone who shares close breathing space. Usually, a long period of time and repeated exposures are needed for TB to spread to others. People with TB disease are most likely to spread it to people who they spend close time with every day. This includes family members, close friends, and co-workers. Tuberculosis is not spread by brief contact in large, open areas or by handling an ill person's eating utensils, books, or furniture.

Not all people with TB disease are easily able to transmit the germ to others. TB disease with a productive cough is more easily spread to other people than TB lung disease with a minimal cough. A person is less likely to spread TB disease once they have been taking medicine for at least two weeks. TB of other body organs is generally not contagious.

What is the difference between Latent TB Infection and TB Disease?

People with latent TB infection have TB germs in their bodies, but they are not sick because the germs are not active. These people do not have symptoms of TB disease, and they cannot spread the germ to others. However, they may develop TB disease in the future. If you have latent TB infection but not TB disease, your doctor may want you to take medications to kill the TB germs to prevent future TB disease from developing. Some people are more likely than others to develop TB disease once they have TB infection. This includes those with HIV infection, diabetes, people who were recently exposed to someone with TB disease, and people with certain medical conditions.

People with TB disease are sick from TB germs that are active, meaning that they are growing and causing harm inside the body. These people usually have symptoms of TB disease. People with TB disease of the lungs or throat can spread germs to others. Oakland County is responsible for ensuring all people diagnosed with TB disease are prescribed the proper medications to treat TB disease.

What should I do if I think I was exposed?

A person with latent TB infection cannot spread germs to other people. You do not need to be tested if you have spent time with someone with latent TB infection. However, if you have spent time with someone with TB disease or someone with symptoms of TB, it may be determined that you should be tested. You can be tested at your doctor's office, or you may visit your local health department for information, assessment, and testing if necessary.

How is tuberculosis diagnosed?

The most common way infection with the TB germ is found is with the tuberculin skin test (TST). The skin test material is placed just under the skin of the inner surface of the lower arm by needle and is read by measuring the amount of swelling two to three days later. A positive skin test shows infection with the TB germ at some time in the past but does not indicate if a person has TB disease.

Disease is diagnosed by symptoms, chest x-ray and other laboratory tests. Only five to ten percent of those infected with the TB germ ever develop active TB disease. but the risk is increased with certain co-existing health conditions.

It may take eight to twelve weeks for the skin test to become positive after breathing the TB germ. Close contacts of a person with active TB disease who are negative on the first skin test should be retested in eight to twelve weeks.

TB tests are generally not needed for people with a low risk of infection from TB bacteria. Certain people should be tested for tuberculosis because they are more likely to get TB disease, including:

• People who have had close contact with someone who has TB disease
• People with HIV infection or another medical problem that weakens the immune system
• People who have symptoms of TB disease (fever, night sweats, cough, and weight loss)
• People from a country where TB disease is common (most countries in Latin America, the Caribbean, Africa, Asia, Eastern Europe, and Russia)
• People who live or work somewhere in the United States where TB disease is more common (homeless shelters, prison or jails, or some nursing homes)
• People who use illegal drugs

How Is tuberculosis treated?

TB disease can be cured by taking several medications for 6 to 12 months. It is very important that people who have TB disease finish the medications and take them exactly as prescribed. If they stop taking the medications too soon, they can become sick again; if they do not take the medications correctly, the germs that are still alive may become resistant to those medications. TB that is resistant to medication is harder and more expensive to treat. For active TB disease, staff of the local health department meets regularly with patients to watch them take their medications. This is called directly observed therapy (DOT).

Is tuberculosis a problem in the United States?

Even though there has been a steady decline in the number of persons with active TB in the United States, it is still a significant problem worldwide and the disease is still spread in the United States. While the majority of TB infections are acquired abroad, TB still remains a public health concern in the United States.