Causes of Diseases Ms. Edmonson

Objectives  Identify characteristics of bacteria, fungi, viruses, parasites and prions.

Disease Causing Agents  Bacteria  Fungi  Viruses  Parasites  Prions

Bacteria  Bacteria consist of only a single cell.  Bacteria are among the earliest forms of life  Bacteria have been found that can live in temperatures above the boiling point and in cold that would freeze your blood.  Bacteria fall into a category of life called the Prokaryotes.

Bacteria  There are thousands of species of bacteria, but all of them are basically one of three different shapes.  rod- or stick-shaped  little ball shaped  helical or spiral shaped

Bacteria  Bacteria live on or in just about every material and environment on Earth.  Each square centimeter of your skin averages about 100,000 bacteria.  Some bacteria are photosynthetic.  Other bacteria absorb food from the material they live on or in.

Bacteria  Some bacteria move about their environment by means of long, whip-like structures called flagella.  Other bacteria secrete a slime layer and ooze over surfaces like slugs.

Bacteria Diseases Some diseases caused by bacteria are:  Anthrax  Tuberculosis  Kennel cough

Fungi  Fungi causes a number of plant and animal diseases.  Fungi are more chemically and genetically similar to animals than other organisms, making fungal diseases very difficult to treat.

Fungi  Fungi are eukaryotic.  Fungi include single-celled creatures that exist individually and multicellular bunches.  Fungi live in the soil and on your body, in your house and on plants and animals, in freshwater and seawater.  They can spread either by forming reproductive spores that are carried on wind and rain.

Fungal Disease Some common fungal diseases are:  Ringworm  Yeast infections

Viruses  A virus is basically a tiny bundle of genetic material.  Viruses are found on or in just about every material and environment on Earth from soil to water to air.  Viruses exist for one purpose only to reproduce. To do that, they have to take over the reproductive machinery of suitable host cells.

Viral Diseases Some viral diseases are:  Foot-and-mouth disease  Parvoviruses

Parasites  Diseases caused by parasites are widespread in domestic animals and wildlife.  Parasites may be internal or external.  External parasites live or feed on the surface of the animal's body.

Parasitic Infections Some parasites that cause infections are:  Internal  Flukes  Roundworms  External  Lice  Mosquitoes  Flies

Prions  Newly identified protein particles called prions have been found in the brains of animals.  They are thought to be misshapen or abnormal versions of proteins normally found in animals or people.

Prions  Very little is known about prions.  Scientists suggest that they spread when a prion comes into contact with the normal version of the protein and causes the normal protein to change shape and become a prion, too.

Prion Diseases  Mad Cow Disease  bovine spongiform encephalopathy  Scrapie

Review  Identify characteristics of bacteria, fungi, viruses, parasites and prions.