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.
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.
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.
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.
Not everyone who is exposed to TB, however, develops active tuberculosis. Many people in the world (about 2 billion) have been infected with latent tuberculosis, but most of them never develop active tuberculosis. This is due to the fact that an individual's immune system can keep the bacteria in control for years or even a lifetime.
Some people are at a higher risk of getting active tuberculosis, including people with HIV infection, malnourished children and adults, injection drug users, people with diabetes or cancer, and people who received incomplete TB treatment in the past. However, healthy people can get active tuberculosis as well.
The most common symptoms of tuberculosis are fever, chills, night sweats, weight loss, fatigue, loss of appetite and coughing up blood.
These symptoms are not specific to tuberculosis because they can occur with many other diseases too. Because of the overlap with other diseases, the diagnosis and therefore the treatment of TB are sometimes delayed.
If your doctor thinks you may have been exposed to tuberculosis, he or she may do a skin test and have you return to the office in 48 to 72 hours to interpret the test result.