Michigan Advisory Committee for Elimination of Tuberculosis (MI-ACET)
General Public Health Care Professionals Epidemiology/Statistics About MI-ACET
What Is TB?
Who Gets TB?
Transmission
Treatment
Skin Testing
Differentiating TB
TB-Like Infections
Where to Go
TB FAQs
Ingham County Tuberculosis Sanatorium, 1926 Photo: Courtesy, ALA-Michigan

Differentiating TB

What is latent TB infection?

In most people who breathe in TB bacteria and become infected, the body is able to fight the bacteria to stop them from growing. The bacteria become inactive, but they remain alive in the body and can become active later. This is called latent TB infection. People with latent TB infection:
  • have no symptoms
  • don't feel sick
  • can't spread TB to others
  • usually have a positive skin test reaction
  • can develop TB disease later in life if they do not receive treatment for latent TB infection

Many people who have latent TB infection never develop TB disease. In these people, the TB bacteria remain inactive for a lifetime without causing disease. But in other people, especially people who have weak immune systems, the bacteria become active and cause TB disease.

What is TB disease?

TB bacteria become active if the immune system can't stop them from growing. The active bacteria begin to multiply in the body and cause TB disease. Some people develop TB disease soon after becoming infected, before their immune system can fight the TB bacteria. Other people may get sick later, when their immune system becomes weak for some reason.
Babies and young children often have weak immune systems. People infected with HIV, the virus that causes AIDS, have very weak immune systems. Other people can have weak immune systems, too, especially people with any of these conditions:
  • substance abuse
  • diabetes mellitus
  • silicosis
  • cancer of the head or neck
  • leukemia or Hodgkin's disease
  • severe kidney disease
  • low body weight
  • certain medical treatments (such as corticosteroid treatment or organ transplants)
Symptoms of TB depend on where in the body the TB bacteria are growing. TB bacteria usually grow in the lungs. TB in the lungs may cause:
  • a bad cough that lasts longer than 2 weeks
  • pain in the chest
  • coughing up blood or sputum (phlegm from deep inside the lungs)
Other symptoms of TB disease are:
  • weakness or fatigue
  • weight loss
  • no appetite
  • chills
  • fever
  • sweating at night