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Commonly referred to simply as TB, tuberculosis is an infectious disease discovered and identified in 1882 by the German physician Robert Koch. The tubercle bacillus is a small, rod-shaped bacterium that can survive for months in a state of dryness and can also resist the action of mild disinfectants.

Although tuberculosis occurs in humans worldwide, historically, TB rates have been higher in urban than in rural communities. Because of greater crowding and poorer sanitation, cities provide greater opportunity for transmission of the disease. Accounts of TB can be found in the writings of the ancient Egyptians, in those of the Greek physician Hippocrates, and in the medical writings of most urbanized societies since then. In the 1700 and 1800s, the disease reached near-epidemic proportions in urbanizing societies of Europe and North America. As recently as the mid-1980s, the number of deaths caused by tuberculosis began to rise again. The resurgence of the disease has been attributed to deteriorating health-care systems, increased poverty and homelessness, and the spread of HIV (human immunodeficiency virus).

There are two ways to spread the tuberculosis infection. One way to spread tuberculosis is the gastrointestinal route by drinking milk infected with the tubercle bacillus. Infections of this sort often affect the bones and joints. The most common mode of transmission is directly from an infected person through the respiratory system. Sneezing, coughing, and even talking release hundreds of tubercle bacilli that may be inhaled by a healthy person. This form of the disease commonly affects the lungs, although almost any organ of the body may be affected, and is known as pulmonary tuberculosis. Ninety percent of all cases of tuberculosis in humans is pulmonary.

Pulmonary tuberculosis occurs in many stages of human life. Some forms only affect infants and a natural immunity develops during childhood. Nearly all clinically recognized cases of disease are post primary pulmonary tuberculosis, which occurs mainly in young adults but can occur at any age. Symptoms include lack of energy, weight loss, persistent cough, and sweating. As the cough increases, the patient may experience severe chest pain. Large areas of the lungs are destroyed as the disease spreads, eventually causing the patient to cough up blood and dead lung tissue.

Even after discovery of the tubercle bacillus, tuberculosis was difficult to diagnose and treat. Sanatariums provided therapeutic rest and nutrition for patients who could afford to go there, but most people struggled at home and depended upon the aid of family members. In the 1940s and 1950s, several antimicrobial drugs were discovered that revolutionized the treatment of patients with tuberculosis. Today, with early and proper drug treatment, most patients are cured of tuberculosis.


Robert Koch

Born Heinrich Hermann on December 11, 1843, in Clausthal, Germany, Robert Koch is one of the founders of the science of bacteriology, discovering the tubercle bacillus in 1882 and the cholera bacillus in 1883.

For his early training, Koch attended the University of Gottingen, graduating in 1866. While at Gottingen, Koch studied medicine under the tutelage of the anatomist and histologist Friedrich Gustave Jacob Henle. In 1840, Henle published the theory that infectious diseases were caused by living microscopic organisms. By the 1870s, Koch began his own work in the field of microbiology. Koch found that dried bacteria could remain viable for years in a range of conditions. Moreover, although the concept that many disease organisms might be cultured outside of the body was introduced by French microbiologist Louis Pasteur, Koch perfected techniques for doing so. Koch's techniques enabled the determination of complete life cycles of various bacteria.

Over the next decade, Koch continued to make strides in the investigation, preservation, and photographing of bacteria. His precise work and ingenious experiments won him recognition as a first rank scientific investigator. His good work and notoriety earned him a position in Berlin in the German Health Office. There he established a laboratory in bacteriology and began to devise new research methods and modify his techniques. On March 24, 1882, Koch announced before the Physiological Society of Berlin that he had isolated and grown the tubercle bacillus.

Koch's work with the tubercle bacillus was momentarily interrupted by the appearance of cholera in Egypt. For fear of cholera transmission to the European mainland, Koch was sent to Egypt to investigate the disease as a member of Germany's government commission. In 1883, Koch discovered the specific bacillus that caused cholera, as well as the cause of amebic dysentery and two varieties of conjunctivitis. Shortly thereafter, Koch proceeded to India and determined that cholera is transmitted via drinking water, food, and clothing.

For all of his extraordinary work in microbiology, Koch had one regret. He was unable to satisfactorily find any adequate curative agent for tuberculosis. Nevertheless, his success in identifying the organism that causes both tuberculosis and cholera and the subsequent prevention of both diseases earned him the Nobel Prize for Physiology or Medicine in 1905.

Robert Koch died May 27, 1910, in Baden-Baden, Germany.


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