Two years ago, I tested positive on a PPD. I chose to do nothing. Six months ago, I got the flu, and I am still sick to this day. I have headaches that never go away, awful joint pain, wheezing, coughing and severe chest pain. I'm tired all the time and short of breath. I have so much mucus in my chest that I feel I should be suctioned. I had a sputum test recently, and it's positive for TB. Is it possible that all these symptoms are from TB? I am 22 years old, and before this I was very healthy and active. Now I just want to rest.

G.G.

Mycobacterium tuberculosis (MTB) is the bacterium that causes tuberculosis. Usually, after a person is infected with MTB, the immune system controls the infection and few if any symptoms develop. However, since the organism is usually not eradicated from the body, it can later reactivate. When this happens, the infection usually causes typical pulmonary (lung) tuberculosis. In rare instances, MTB can cause other syndromes, such as meningitis (inflammation of the membranes covering the brain and spinal cord), infection of the spine, or widespread infection of several organ systems. Once infected, a person's lifetime risk of developing disease is about 10 percent. Nearly half of this risk is in the first two years following infection.

The PPD (purified protein derivative) or tuberculin test is a skin test designed to determine if a person is infected with MTB. A small amount of protein derived from the organism is injected into the skin, and the person is presumed to be infected if a reaction develops (a raised, hardened area of skin larger than a defined size).

You had a positive PPD when you were tested two years ago, meaning that you were infected with MTB at that time, although you may have been initially infected much earlier. Experts usually recommend that people with a positive skin test who are younger than 35 take a medication called isoniazid (INH) for six months, which can greatly reduce their risk of developing active tuberculosis. The reason for this age cutoff is that people older than 35 have a higher risk of experiencing INH-related liver toxicity than those under 35. However, certain people with a positive skin test who are more likely to develop active TB are given isoniazid even if they are older than 35.

Your symptoms are perfectly consistent with pulmonary tuberculosis -- in fact, you seem to have a typical case. Pulmonary TB is a chronic (persistent) pneumonia, and you report several months of cough and chest pain, as well as the production of quantities of sputum (saliva mixed with mucus). I would expect that you also have experienced weight loss and fever, or at least night sweats. You also had a sputum sample that was positive for TB, which essentially proves the diagnosis. While it is theoretically possible that this test was a result of an error in the laboratory, such an error is extremely rare. A single positive sputum test in someone with your symptoms is essentially definitive.

You have tuberculosis and you should undergo treatment. Generally, people in your situation should be started on a combination of four different antibiotics. Once your doctor has learned which drugs are active against the strain of MTB responsible for your infection, one or two can be discontinued. There are acceptable regimens that can be given for six months with a very high success rate. All of your contacts -- such as family members, friends, and coworkers -- should have a skin test to determine if you infected them. Also, if there are any children in your household, they should be tested and, if infected, treated with isoniazid.