Tuberculosis -- Are You at Risk?

You have not gone out with your friends in months. All of a sudden, you realize, you are too tired to even go to the movies.

Tuberculosis is caused by infection with the bacteria Mycobacterium tuberculosis.

You have lost weight without even trying. The constant cough keeps you up at night, but you are used to it by now -- the doctors you have seen could not find anything wrong with you. Could you have been infected with tuberculosis?

Though many consider tuberculosis, or TB, to be a disease of the past, emerging evidence suggests that this infection may present more of a threat than many realize.

In 2005, there were an estimated 8.8 million new cases of TB worldwide, according to the recently released statistics from the World Health Organization. In that same year, 1.6 million people died from the illness.

And as new, drug-resistant strains of TB emerge, many Americans are starting to realize that the threat may not remain confined to the developing nations for much longer.

What is Tuberculosis?

TB is an airborne infection caused by a certain type of bacteria. People who are exposed usually get an infection without symptoms and they are not contagious. This is called "latent tuberculosis."

People with latent tuberculosis are at risk of developing "active tuberculosis" in the future if they do not get treated. Active tuberculosis is the classic disease we think of that causes a bloody cough, fever and weight loss.

Among infectious diseases, TB is the second leading killer of adults in the world. It is also the No. 1 infectious disease killer in persons infected with HIV, the virus that causes AIDS.

Who Is at Risk?

Everyone is at risk of getting infected with tuberculosis, but people with the highest risk of being exposed to TB and developing latent tuberculosis are health care workers and immigrants from countries where TB is common.

It usually takes on average eight hours of contact with someone who has TB to become infected, so infection is often passed around among family members because they spend a lot of time together in the home.