Tuberculosis

Tuberculosis Overview

Tuberculosis is a chronic bacterial infection caused by a germ called Mycobacterium tuberculosis. Tuberculosis is an infectious disease that is spread through the air when a person with the disease coughs or sneezes. A person may become infected with TB when they breathe the air droplets from the person who is sick with the disease. The disease commonly infects the lungs but can infect other parts of the body including the spine, brain or kidney. Below are the characteristics of TB infection and TB disease

Latent TB Infection

Not everyone who becomes infected becomes sick with the disease itself. This is because the body's immune system is able to keep the number of TB germs low enough to prevent the disease from developing. The infection at this point is called latent TB infection.

No symptoms (don't feel sick)
Cannot spread the infection to others
Diagnosed with a positive TB skin test
Can develop into active TB disease
Treatment available to prevent active TB disease

Active TB Disease

If the TB germs become too numerous for the immune system to contain the person becomes sick with active TB disease.

Have symptoms (including cough for > 3 weeks, coughing up blood, chest pains, fever, chills, night sweats, unintended weight loss, appetite loss)
Can spread to others
Diagnosed with lab tests and chest x-ray
Treatment available to treat the active TB disease

Conditions That Make the Development of Active TB More Likely

People with particular health conditions are more likely to develop active disease once infected (see below). The development of active TB disease from latent infection may take months to years to occur. Both TB infection and disease can be readily diagnosed and treated.

HIV infection
Diabetes Mellitus
Leukemia or Hodgkin's disease
Silicosis
Low body weight
Corticosteroid Treatment or Organ Transplantation treatment
Certain treatment for Rheumatoid Arthritis or Crohn's disease
Chronic kidney disease or dialysis
Active cancer of the head and neck

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Last Reviewed: Sep 30, 2005

Allan B Chiunda, MPH
Senior Analyst/Project Manager, PhD Candidate
Tuberculosis Research Unit
School of Medicine
Case Western Reserve University

Catherine A Curley, MD, MS
Director and Assistant Professor
Tuberculosis Clinic
MetroHealth Medical Center
School of Medicine
Case Western Reserve University