Skip to content
My WebMD Sign In, Sign Up

Lung Disease & Respiratory Health Center

Font Size
A
A
A

Understanding Tuberculosis -- the Basics

What Is Tuberculosis?

Tuberculosis, commonly known as TB, is a bacterial infection that can spread through the lymph nodes and bloodstream to any organ in your body. It is most often found in the lungs. Most people who are exposed to TB never develop symptoms because the bacteria can live in an inactive form in the body. But if the immune system weakens, such as in people with HIV or elderly adults, TB bacteria can become active. In their active state, TB bacteria cause death of tissue in the organs they infect. Active TB disease can be fatal if left untreated.

Because the bacteria that cause tuberculosis are transmitted through the air, the disease can be contagious. Infection is most likely to occur if you are exposed to someone with TB on a day-to-day basis, such as by living or working in close quarters with someone who has the active disease. Even then, because the bacteria generally stay latent (inactive) after they invade the body, only a small number of people infected with TB will ever have the active disease. The remaining  will have what's called latent TB infection -- they show no signs of infection and won't be able to spread the disease to others, unless their disease becomes active.

Because these latent infections can eventually become active, even people without symptoms should receive medical treatment. Medication can help get rid of the inactive bacteria before they become active.

TB was once a widespread disease. It was virtually wiped out with the help of antibiotics developed in the 1950s, but the disease has resurfaced in potent new forms -- multidrug-resistant TB and extensively drug-resistant TB. Today, these new and dangerous forms of the disease -- resistant to some of the commonly used drug treatments -- have created a public health crisis in many large cities worldwide. If you have TB -- in its active or latent state -- you must seek medical treatment.

WebMD Medical Reference

Reviewed by Varnada Karriem-Norwood, MD on April 02, 2013

Today on WebMD

Hot Tub Disease
Article
Lung Disease Health Check
HEALTH CHECK
 
Cigarette butts in ashtray
Article
Household Hazards For People With Copd
Article
 

Bronchitis Overview
SLIDESHOW
Copd Myth Fact Quiz
QUIZ
 
Living With Copd
VIDEO
Energy Boosting Foods
SLIDESHOW
 

cigarette butts snuffed out in ashtray
SLIDESHOW
Healthy Home Health Check
TOOL
 
Senior woman stretching
Article
Diagnosing Copd
VIDEO
 

WebMD Special Sections