BACTERIA AND DISEASE

A century ago in the United State and even today in the less developed countries, at least 25% of the children died of bacteria infections before reaching puberty. In the united states and other Western nations, this figure is now below 5% as a result of improved sanitation, hygiene, and medical care.

The control of Typhoid fever alone is perhaps the greatest triumph of organized preventive medicine. As late as 1900 the annual death rate from typhoid fever in United States was more 30 per 100, 000; by 1944 the rate hade decreased to 0,4 per 100, 000.

For the world as the whole however, typhoid fever remain a major disease.

History.

To account for the spread of certain disease, thoughtful people since ancient times postulated the existence of transmissible agents of infections invisible to the naked eye, In 1546 the Italian physician Girolamo fracastoro proposed the germ theory of disease, describing the transmission of disease by ‘Seminaria’ or living germ. Visualization of germ could not take place until the microscope had been invented. However, bacteria and other microscopic organism were first seen in 1676 by a Dutch linen-draper, Antony Van Leeuwenhoek, who made single lens microscope with sufficient magnification to observe the major types of bacteria as well as protozoans, yeasts, and one-celled algae. Leeuwenhoek is regarded as the father of bacteriology.

The first important classification of bacteria was made in the early 1800s. In 1829, Christian Gottfried established the genus Bacterium, using a term formed from the greek word Bacterion , signifying a rod.

The entire subject of bacteriology has taken its common name from the prominence of rodlike forms of bacteria, now called bacilli. Eventually, bacteria were classified as plants; this remained the dominant view until the 1960s. Bacteria are now clasisified as Monerans.

An experimental science of bacteriology emerged slowly and required the development of special methodology. The key was the use of sterile (germ-free) materials and antiseptic technique; a singe contaminating cell can ruin an experiment in bacteriology. Only after learning to avoid such contamination could investigators recognized the existing variety of bacteria, their distribution, and their major rules.