The National Academies

The National Academies: What You Need To Know About Infectious Disease

What You Need To Know About Infectious Disease


Tuberculosis, or TB, is caused by the bacterium Mycobacterium tuberculosis. Although TB usually settles in the lungs, it can affect other parts of the body, including the kidney, spine, and brain. It is an airborne disease, spread when an infected person contaminates the air by coughing, sneezing, or even talking. TB is more prevalent in the developing world, where treatment is not as widespread, and can be particularly problematic for people with compromised immune systems. In 2014, 9.6 million people contracted TB, and 1.5 million people died from the disease.

TB can become resistant to the drugs prescribed to treat it. Multidrug-Resistant TB (MDR-TB) refers to an infection resistant to the two most commonly prescribed medications. Extensively Drug Resistant TB (XDR-TB), a relatively rare problem, refers to conditions resistant to both first- and second-line medications used to treat the disease.

For pulmonary tuberculosis, the most common type of TB, symptoms are usually a bad cough that lasts 3 weeks or longer, pain in the chest, and blood in the mucus. Other symptoms may include weakness or fatigue, loss of appetite and subsequent weight loss, fever, chills, and night sweats. It is possible to have latent TB infection, which has no symptoms and cannot be spread to others. People with latent TB may never develop an active case.

Currently there are 10 antibiotics approved for the treatment of TB in the United States. A regimen based on these options is usually prescribed for 2 months, followed by continuation therapy for an additional 4 to 7 months. It is very important to complete the regimen exactly as prescribed. Failure to do so is a major factor in the development of MDR-TB and XDR-TB, both of which are much harder to treat. Patients with MDR-TB should work with doctors knowledgeable in this field and be closely observed during the treatment period. For people with XDR-TB, who are resistant to both first- and second-line medications, treatment is extremely difficult.

Avoid close contact with known TB patients. Limit time spent with TB patients in hospitals, clinics, homeless shelters, or other crowded, enclosed areas. If you will be working in an area where you are likely to encounter TB patients, such as health care settings, consult with infection control or occupational health experts for guidance regarding preventing exposure. If you think you have been exposed to TB, contact your doctor or local health department immediately. There is a vaccine available for TB but it is not recommended for use in the United States because of the relatively small numbers of people who have the disease.


Explore Other Topics

What do you know about infectious disease?

True or False: Our bodies contain at least 10 times more human cells than bacterial cells.

  • Sorry, that’s incorrect.

    Our bodies contain at least 10 times more bacterial cells than human cells. 

  • Correct!

    Our bodies contain at least 10 times more bacterial cells than human cells. 

Infectious Disease Defined


A broad group of molecules including fats and waxes that are insoluble in water and are an important part of living cells.

View our full glossary