KEY CONCEPT Germs cause many diseases in humans.

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KEY CONCEPTGerms cause many diseases in humans.
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• Diseases caused by germs, such as the E. Coli
  bacteria can be fatal (death)
• 1330-1352, the bacteria that caused the Black
  Death or the Plague originated from fleas on
  rats
• Has killed approx.
• 100 MILLION
• people
• New diseases
• HIV
• SARS
• Avian Flu (bird flu)
• Swine Flu

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• Germ theory proposes that microorganisms cause
  diseases.
• led to rapid advances in understanding disease
• Can be infectious (polio, flu), caused by germs
• or noninfectious (cancer, heart disease) caused
  by genes or lifestyle

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• Disease-causing agents are called pathogens.
• What would happen if pathogens were eliminated?
• We wouldnt get sick

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There are different types of pathogens.

• Bacteria are single-celled organisms.
• cause illness by destroying cells
• release toxic chemicals
• Exs
• E. Coli
• Salmonella
• Food Poisoning

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• Viruses are disease-causing strands of DNA or RNA
  that are surrounded by a protein coat.

• Take over a healthy cell
• Force cells to produce more of the virus
• Smaller than bacteria
• Exs
• HIV
• Influenza
• Herpes
• Common Cold
• AIDS

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• Fungi can be multicellular or single-celled.

• take nutrients from hosts cells
• occur in warm and damp places

Ex Athletes foot, yeast, mold
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• Protozoa are single-celled organisms

• Prey on other cells
• use host cells to complete their life cycles
• take nutrients from host cell
• Ex Malaria, dysentery

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• Parasites are multicellular organisms.

• grow and feed on a host
• possibly kill the host

Ex Heart worm Round worm
Elephantiasis- mosquitos
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• Vectors any person or animal that carries and
  transmits a pathogen to another living organism.

• Direct contact requires touching an infected
  individual. Includes
• kissing
• sexual intercourse
• hand shaking
• bite

Ex Lime Disease- ticks Malaria- mosquito West
Nile Virus- mosquito Rabies- rabid animal HIV-
infected person
tick
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Pathogens can enter the body in different ways.

• Direct contact require an infected person or
  animal to physically touch a healthy person Ex
  Rabies, HIV
• Indirect contact does not require touching an
  infected individual.

• touching an infected surface
• breathing in infected air Ex SARS
  Tuberculosis

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• Different pathogens cause common infectious
  diseases.