About Us | Privacy | Site Map
February 6, 2012
Font Size
A
A
A
1
...

Tuberculosis

Medical Author:
Medical Editor:

Causes of Tuberculosis

Learn about causes of tuberculosis.All cases of TB are passed from person to person via droplets. When someone with TB infection coughs, sneezes, or talks, tiny droplets of saliva or mucus are expelled into the air, which can be inhaled by another person.

  • Once infectious particles reach the alveoli (small saclike structures in the air spaces in the lungs), another cell, called the macrophage, engulfs the TB bacteria.


    • Then the bacteria are transmitted to the lymphatic system and bloodstream and spread to other organs occurs.


    • The bacteria further multiply in organs that have high oxygen pressures, such as the upper lobes of the lungs, the kidneys, bone marrow, and meninges -- the membrane-like coverings of the brain and spinal cord.

Learn more about causes of tuberculosis »

Tuberculosis Overview

Tuberculosis (TB) describes an infectious disease that has plagued humans since the Neolithic times. Two organisms cause tuberculosis -- Mycobacterium tuberculosis and Mycobacterium bovis.

Physicians in ancient Greece called this illness "phthisis" to reflect its wasting character. During the 17th and 18th centuries, TB caused up to 25% of all deaths in Europe. In more recent times, tuberculosis has been called "consumption."

  • Robert Koch isolated the tubercle bacillus in 1882 and established TB as an infectious disease.


    • In the 19th century, patients were isolated in sanatoria and given treatments such as injecting air into the chest cavity. Attempts were made to decrease lung size by surgery called thoracoplasty.


    • During the first half of the 20th century, no effective treatment was available.


    • Streptomycin, the first antibiotic to fight TB, was introduced in 1946, and isoniazid (Laniazid, Nydrazid), originally an antidepressant medication, became available in 1952.

  • M. tuberculosis is a rod-shaped, slow-growing bacterium.


    • M. tuberculosis' cell wall has high acid content, which makes it hydrophobic, resistant to oral fluids.


    • The cell wall of Mycobacteria absorbs a certain dye used in the preparation of slides for examination under the microscope and maintains this red color despite attempts at decolorization, hence the name acid-fast bacilli.

  • M. tuberculosis continues to kill millions of people yearly worldwide. In 1995, 3 million people died from TB.


    • More than 90% of TB cases occur in developing nations that have poor hygiene and health-care resources and high numbers of people infected with HIV.


  • In the United States, the incidence of TB began to decline around 1900 because of improved living conditions.


    • TB cases have increased since 1985, most likely due to the increase in HIV infection.


  • Tuberculosis continues to be a major health problem worldwide. In 2008, the World Health Organization (WHO) estimated that one-third of the global population was infected with TB bacteria.


    • 8.8 million new cases of TB developed.


    • 1.6 million people died of this disease in 2005.


    • Each person with untreated active TB will infect on average 10-15 people each year.


    • A new infection occurs every second.


    • In 2009, the TB rate in the United States was 3.8 cases per 100,000 population, a slight decrease from the prior year. Four states (California, Florida, New York, and Texas) accounted for the majority of all new TB cases (50.3%).


  • With the spread of AIDS, tuberculosis continues to lay waste to large populations. The emergence of drug-resistant organisms threatens to make this disease once again incurable.


  • In 1993, the WHO declared tuberculosis a global emergency.
1
...

Viewer Comments & Reviews

Tuberculosis - How Was Diagnosis Established

The eMedicineHealth physician editors ask:

How was the diagnosis of your tuberculosis established?

Women's Health

Find out what women really need.



Tuberculosis

Chemical Pneumonia Overview

Chemical pneumonia is an unusual type of lung irritation. Pneumonia usually is caused by a bacteria or virus. In chemical pneumonia, inflammation of lung tissue is from poisons or toxins. Only a small percentage of pneumonias are caused by chemicals.

  • Many substances can cause chemical pneumonia, including liquids, gases, and small particles, such as dust or fumes, also called particulate matter. Some chemicals only harm the lungs; however, some toxic materials affect other organs in addition to the lungs and can result in serious organ damage or death.
  • Aspiration pneumonia is another form of chemical pneumonia. Aspiration means that you breathe oral secretions or stomach contents into your lungs. The inflammation comes from the toxic effects of stomach acid and enzymes on lung tissue. Bacteria from the stomach or mouth can also cause a bacterial pneumonia.
  • Chemical pneumonia is only one t...

Read the Chemical Pneumonia article »


Read What Your Physician is Reading on Medscape

Tuberculosis »

Tuberculosis (TB) is the most common cause of infectious disease–related mortality worldwide.

Read More on Medscape Reference »

Medical Dictionary


Use Pill Finder Find it Now

Pill Identifier on RxList

  • quick,
    easy,
    pill identification

Find a Local Pharmacy

  • including
    24 hour
    pharmacies