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 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.

Since 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.

At one time, TB was 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.

What Is Tuberculosis? What Causes Tuberculosis?

Tuberculosis (TB) is an infectious disease that is caused by a bacterium called Mycobacterium tuberculosis. TB primarily affects the lungs, but it can also affect organs in the central nervous system, lymphatic system, and circulatory system among others. The disease was called "consumption" in the past because of the way it would consume from within anyone who became infected.

According to Medilexicon`s medical dictionary, tuberculosis is "A specific disease caused by