7C37: Germ Theory History of Germs & Disease Name / Hour / Date 7C37: Germ Theory History of Germs & Disease

Background Microbes were discovered in the late 1600’s But the idea that these tiny organisms could cause disease did not develop until 1860’s, about 150 years ago. Why did it take so long to figure it out?

Robert Hooke (1635-1703) English scientist drew observations of the natural world & wrote Micrographia (1665) Made a compound microscope and drew the cork plant. He saw what looked like little rooms & called them cells, meaning rooms.

Anton Leeuwenhoek (1632-1723) Made microscopes that magnified 200x. Described microbes in water in 1673 as “moving beasties like fine grains of sand”. He was not a good artists. He wrote precise descriptions but hired someone else to draw.

Schleiden, Schwann, Siebold Schleiden (1804-1881): Botanist who used microscopes to study plants. Suggested that all plants are made of cells. Schwann (1810-1882): Biologist suggested animals are also made of cells. Siebold (1804-1885): Biologist suggested microbes are made of individual cells.

Ignaz Semmelweiss (1818-1865) Believed some diseases were infectious and could be spread. He tried washing his hands between patients and reduced the death rate Because he could not explain why it worked many doctors refused to change their ways and still would not wash their hands.

Rudolph Virchow (1821-1902) Polish doctor suggested (1850) that all cells reproduce, divide, and grow. He suggested that diseases are caused by cells that don’t work properly in people . This is only true for cancer and hereditary diseases.

Louis Pasteur (1822-1895) French chemist noticed microbes caused wine to spoil, but using heat could kill them Today we “pasteurize” milk by heating it, to kill microbes and keep milk safe to drink. He suggested that microbes he called germs caused infectious diseases and could spread.

Robert Koch (1843-1910) German doctor who identified germs that caused several diseases. He then isolated those germs and grew microbe cultures. Cultures are individual groups of microbes grown in agar, a gelatin he invented.

Nightingale, Lister, Halsted Florence Nightingale: English nurse (1860) kept hospitals clean. Fewer soldiers died. Joseph Lister: Scottish surgeon (1867) used antiseptic to clean hands, aprons, and instruments. Patient deaths decreased. William Halsted: American surgeon (1890) sterilized rubber gloves (too hot for hands) for surgery.

Spontaneous Generation Previously people believed that living things grew from non-living things. They thought that plants grew from dirt alone and that no seeds were needed. After some time a plant would just grow from the soil. It took many experiments to disprove this.

Disease

Spread of Infection Infectious disease begins by spreading slowly to a few people. Each person spreads it to more people as it moves quicker through the population. Eventually people build up their defenses to it and no longer spread it to others. The disease is no longer a problem.

C37 Germ Analysis 1 paragraph each Why is germ theory of disease important in understanding infectious disease? How important was the development of the microscope in discovering the cause of infectious disease? Which of the previous scientists would you most like to work with? Why?

Germ Project Write Name, Hour, Date, Title (above), and the Name of your germ. Fold sheet of paper in half hamburger style. Draw pictures of your germ on top half and draw details, colors, background, etc. Then, Write three paragraphs about your germ 1) what it is (describe) 2) the disease it causes 3) how to cure it / get rid of it, etc.