1. Caused by bacteria and viruses
Diseases
Caused by bacteria and viruses

2. Disease causing agents
PATHOGENS
Disease causing agents
Viruses reproduce by infecting living cells and can cause harm to the host
Bacteria requires nutrients and energy which can interfere with the host’s ability to function properly

3. Bacterial disease in humans
The growth of bacterial pathogens disrupts the body’s normal functions
Louis Pasteur (French chemist) was the first person to show that bacteria causes diseases
Established the Germ Theory

4. Bacteria produces disease in 2 ways
directly breaking down cells for food
Ex. Mycobacterium tuberculosis (Tuberculosis) is inhaled into the lungs where it destroys lung tissues. It can also enter a blood vessel and travel to new sites
releasing toxins (poison) that travel through the host
Ex. Streptococcus (strep throat) releases toxins into the bloodstream, causing scarlet fever
Ex. Corynebacterium diphtheriae (Diphtheria) releases toxins in the throat and causes breathing problems, heart failure, paralysis, and death.

5. Preventing Bacterial disease
Vaccine
Many bacteria diseases can be stopped by stimulating the body’s immune system
Antibiotics- compounds that block the growth and reproduction of bacteria
Ex. Penicillin and tetracycline

6. Bacterial disease in animals
Animals can be infected by bacterial disease as well
Which can transmit to ranchers and animal handlers
Ex. Bacillus anthracis (anthrax) are often found in sheep
Produces tough, resistant spores that can last for years
Was developed as a biological weapon
Sverdlovski (Soviet Union) in 1979 hundreds of people died when anthrax was accidently released.

7. Controlling bacteria
Although most bacteria are harmless (many are beneficial), there are various methods used to control the growth of bacteria.
Sterilization
Destroys all bacteria through the use of heat as most bacteria can’t survive high temperature for a long time

8. Controlling bacteria Disinfectants
Chemical solutions that kill pathogenic bacteria (AKA antibacterial products)
Overuse of antibacterial products increases the chances that common bacteria will evolve to become more resistant and therefore more dangerous and difficult to kill

9. Food storage and processing
Controlling bacteria
Food storage and processing
Refrigeration stores food at lower temperatures which keeps it fresher
Raising the temperature of the food to the point where bacteria are killed
Ex. Boiling, frying, or steaming

10. Viral diseases in humans
Viruses attack and destroy certain cells causing symptoms of the disease
Ex. Polio virus infects and kills cells of the nervous system producing paralysis
Some viruses will infect cells to change their patterns of growth and development
Vaccines are a way to prevent viral diseases
Many decades of childhood vaccines against smallpox have virtually eliminated this disease

11. Viral disease in animals
Ex. An epidemic of foot-and-mouth disease infected thousands of cattle in Europe in the late 1990’s
Some animal viruses can cause cancer
Oncogenic – tumor-causing viruses

12. Viral disease in plants
Viruses can also infect plants
Ex. Tobacco mosaic virus, potato virus, etc
Many plant viruses are spread by insects

13. Viral disease in plants
Plant viruses contain a core of nucleic acid and a protein coat, however, they have a hard time entering plant cells due to the cell walls
Plant viruses developed a way to take advantage of even minor damage to plant tissues (ex. Tears in leaves, breaks in stems and roots, or microscopic cell wall damaged caused by human or animal contact)