Tuberculosis (TB) is a serious disease that spreads through the air. It is caused by a bacterium called Mycobacterium tuberculosis. Tuberculosis usually affects the lungs. However, it can affect other parts of the body, such as the central nervous system. About 10-15 million Americans are infected with tuberculosis. For most people with healthy immune systems, this is not a problem. Nine out of 10 of them won't develop active disease with symptoms.
The risk is great, however, for people who are HIV-positive. That's because tuberculosis takes advantage of a weakened immune system, which is why it's called an opportunistic infection. Worldwide, tuberculosis is the leading cause of death for people infected with HIV (human immunodeficiency syndrome). If you are HIV-positive, you should be tested for tuberculosis. Prevention and treatment not only help control tuberculosis, but also help prevent greater damage to your immune system.
Antiretroviral therapy -- or ART -- revolutionized HIV treatment in the past few decades. And newer improvements, like one-pill-a-day drugs, are making life with HIV easier and safer.
"HIV really is a chronic disease now," says Brad Hare, MD, medical director of the HIV/AIDS Division at San Francisco General Hospital. "It's like diabetes or high blood pressure." As long as you manage it well, you should expect a long, healthy life.
The bacteria that cause tuberculosis travel through the air, such as in a cough or sneeze. But you are not likely to get the disease through a single exposure. And you can't get it from sharing dishes or utensils, or through touching someone who has it.
You are more likely to get tuberculosis from constant exposure to an infected person, such as someone with whom you work or live. You are likely to get tuberculosis in places with poor ventilation or crowded conditions. If you are HIV-positive, discuss with your doctor whether it is safe to continue working in places like:
A hospital, clinic, or doctor's office
A nursing home
A jail or prison
A shelter for homeless people
HIV and the Types of Tuberculosis Infection
There are two types of tuberculosis infection, latent and active.
If you have a latent infection, the germs remain in your body, but don't cause symptoms.
If your immune system is weak, the germs can multiply and become active, causing symptoms and disease.
Active disease is more likely if you have HIV, especially if your CD4 count is under 200. (CD4 cells are a type of immune system cell.) However, active tuberculosis can happen no matter what your CD4 level is. If you are infected with both HIV and TB, you are at least 10 times more likely to develop active TB than someone without HIV. If you have both infections, you have AIDS (acquired immunodeficiency syndrome), a more advanced stage of HIV.
These are other factors that can increase your risk for active tuberculosis:
Alcohol or injection drug use
Being young (less than 5 years old), old (older than 65)
Being a person of color
HIV and the Symptoms of Tuberculosis
These are common signs and symptoms of tuberculosis:
A cough that lasts for more than two to three weeks