TB

Definition

Tuberculosis (TB) is a potentially serious infectious disease that primarily affects your lungs. The bacteria that cause tuberculosis are spread from person to person through tiny droplets released into the air via coughs and sneezes.

Tuberculosis was once rare in developed countries, but the number of TB cases began increasing in 1985. Part of the increase was caused by the emergence of HIV, the virus that causes AIDS. HIV weakens a person’s immune system so it can’t fight the TB germs.

Many strains of tuberculosis can resist the effects of the drugs most commonly used to treat the disease. People who have active tuberculosis must take several different types of medications together for many months to eradicate the infection and prevent development of antibiotic resistance.

Symptoms

Although your body may harbor the bacteria that cause tuberculosis, your immune system usually can prevent you from becoming sick. For this reason, doctors make a distinction between:
  • Latent TB:In this condition, you have a TB infection, but the bacteria remain in your body in an inactive state and cause no symptoms. Latent TB, also called inactive TB or TB infection, isn’t contagious.
  • Active TB:This condition makes you sick and can spread to others. It can occur in the first few weeks after infection with the TB bacteria, or it might occur years later. Most people infected with TB germs never develop active TB.
  • Signs and symptoms of active TB include:Cough, Unexplained weight loss, Fatigue, Fever, Night sweats, Chills,
    Loss of appetit.

Causes

Tuberculosis is caused by bacteria that spread from person to person through microscopic droplets released into the air. This can happen when someone with the untreated, active form of tuberculosis coughs, speaks, sneezes, spits, laughs or sings.

Although tuberculosis is contagious, it’s not especially easy to catch. You’re much more likely to get tuberculosis from someone you live with or work with than from a stranger. Most people with active TB who’ve had appropriate drug treatment for at least two weeks are no longer contagious.

Tests and diagnosis

During the physical exam, your doctor will check your lymph nodes for swelling and use a stethoscope to listen carefully to the sounds your lungs make when you breathe.

The most commonly used diagnostic tool for tuberculosis is a simple skin test. A small amount of a substance called PPD tuberculin is injected just below the skin of your inside forearm. You should feel only a slight needle prick.

Within 48 to 72 hours, a health care professional will check your arm for swelling at the injection site. A hard, raised red bump means you’re likely to have TB infection. The size of the bump determines whether the test results are significant. Results can be wrong

The TB skin test isn’t perfect. Sometimes, it suggests that people have TB when they really don’t. It can also indicate that people don’t have TB when they really do.

A false-positive test may happen if you’ve been vaccinated with the bacillus Calmette-Guerin (BCG) vaccine. This tuberculosis vaccine is seldom used in the United States but is widely used in countries with high TB infection rates.