Tuberculosis (TB) is a contagious bacterial infection caused by Mycobacterium tuberculosis that primarily affects the lungs and is spread through the air from person to person by droplets. Infection occurs by inhaling these droplets after an infected person coughs, sneezes, speaks, sings, or laughs. Anyone can get tuberculosis, but risk increases with close or prolonged contact with a person with active TB disease or presence of a health problem that weakens the immune system. It is possible to be infected with tuberculosis more than once.
About 1.7 billion people, 23% of the world’s population, are estimated to have a latent TB infection, and are thus at risk of developing active TB disease during their lifetime. In 2017, 10.4 million people worldwide became sick with active TB disease. In the United States, 9,093 people became sick with active TB disease with the highest rates among people with HIV and those born in countries were tuberculosis is common.
Tuberculosis can remain inactive in the body, a condition known as latent tuberculosis infection (LTBI). One is not sick or contagious with latent tuberculosis. However, without treatment about 5% to 10% of people with latent TB will develop active TB disease. With active TB disease the person becomes very sick, contagious and must be isolated. Students with active TB disease risk their grades and enrollment and may infect friends and classmates. Symptoms of active tuberculosis disease include: