Fact Sheet Number 515
- WHAT IS TB?
- TB AND HIV: A BAD PAIR
- HOW IS TB DIAGNOSED?
- HOW IS TB TREATED?
- MEDICATION PROBLEMS
- THE BOTTOM LINE
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PrintTuberculosis (TB) is an infection caused by bacteria. Tuberculosis
usually affects the lungs, but sometimes can affect other organs.
TB is a very serious disease worldwide. Almost one-third of
the world’s population is infected with TB, although a healthy
immune system can prevent active disease.
The name tuberculosis comes from tubercles. These are small,
hard lumps that form when the immune system builds a wall around
the TB bacteria.
There are two kinds of active TB. Primary TB occurs
soon after a person is first exposed to TB. Reactivation
TB occurs in people who were previously exposed to TB. If their
immune system is weakened, TB can break out of the tubercles and
cause active disease. Most of the cases of TB in people with HIV
disease are due to reactivation of a previous TB infection.
Active TB can cause the following symptoms: coughing for more
than 3 weeks, weight loss, constant fatigue, night sweats, and
fevers. These are very much like the symptoms caused by Pneumocystis
carinii pneumonia (PCP), but TB can occur at much higher CD4+ levels.
TB can be transmitted through the air, when someone with TB
coughs or sneezes. You can develop TB easily if you have advanced
HIV disease, or if you are exposed to a very infectious form of
TB. You can become infected with TB at any T-cell level.
BAD PAIR
Many viruses and bacteria live in our bodies. A healthy immune
system will control these germs so they won’t make you sick. If
HIV weakens your immune system, they can cause opportunistic
infections.
The rate of TB for people with HIV in the United States is
40 times the rate for people who aren’t HIV-infected. TB rates
all over the world are increasing because of HIV disease.
TB can make HIV multiply faster, and make HIV disease worse.
This makes it important for people with HIV to prevent and treat
TB.
There is a simple skin test for TB. A protein found in TB bacteria
is injected into the skin of your arm. If your skin reacts with
swelling, you have probably been infected with the TB bacteria.
People with HIV should get a TB skin test to find out if they
were exposed to TB in the past.
If HIV or another disease has damaged your immune system, you
might not show any reaction to the skin test, even if you’re infected.
This condition is called “anergy”. If you have anergy,
other tests might show if you are infected with TB.
A positive skin test doesn’t always mean you have active TB.
Your doctor will check x-rays of your lungs, ask you about other
symptoms, and try to grow TB bacteria from a sample of your saliva.
This can take four weeks. It is difficult to diagnose TB, because
it can look like pneumonia, other lung problems, or other infections.
If you are infected with TB, but don’t have the active disease,
you will probably be treated with a drug called isoniazid (INH)
for at least 6 months, or with INH plus one or two other drugs
for 3 months. A study published in 2001 showed that the multi-drug
treatments are more effective than INH alone. INH can cause liver
problems, especially for black or Hispanic women.
If you have active TB disease, you will be treated with antibiotics.
Because the TB bacteria can develop resistance to individual drugs,
you will be given a combination of antibiotics. Also, TB is hard
to cure, and the drugs have to be taken for at least 6 months.
If you don’t take all the drugs, then the TB in your body might
become resistant and the drugs will stop working.
There is a type of TB that is already resistant to some antibiotics.
This is called multi-drug resistant TB, or MDR-TB. (No cases of
MDR-TB have been reported in New Mexico.) Despite these problems,
over 90% of cases of TB can be cured with antibiotics.
Some of the antibiotics used to treat TB can damage your liver
or kidneys. So can some of the drugs used to fight HIV. It can
be difficult to take drugs for both TB and HIV at the same time.
Also, many anti-HIV drugs interact with some drugs used to fight
TB. Rifampin or rifabutin are commonly used to fight TB. They
can drop the levels of HIV drugs in your blood too low to control
HIV. The HIV drugs can raise the levels of these TB drugs high
enough to cause serious side effects.
Rifampin should not be used if you are taking anti-HIV medications.
Rifabutin can be used in some cases, but the dosage might have
to be changed. There are special guidelines for your doctor to
use if you take drugs to fight TB and HIV at the same time. Also,
people with less than 100 T-cells should take rifabutin at least
3 times a week. This reduces the risk of their TB becoming resistant
to rifabutin.
TB is a very serious disease worldwide and kills more people with
HIV than any other disease. TB and HIV both make each other worse.
There are effective treatments for TB infection, and for active
TB disease. If you are exposed to TB, or have signs of TB, get
tested and treated.
The treatments for TB take a long time, and can be difficult
to take at the same time as drugs against HIV, but they can cure
TB. Some TB drugs interact with HIV drugs, so treatment has to
be carefully planned if you have both HIV and TB.
Revised May 6, 2002
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