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Pathogenic Organisms
Types of Pathogens
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There are 5 different types of pathogens.
Pathogens – o r g a n i s m s t h a t c a u s e d i s e a s e
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Viruses
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Bacteria (prokaryotic)
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Fungi (eukaryotic)
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Protozoa (eukaryotic)
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Pathogenic Animals (eukaryotic)
VIRUSES
BACTERIA
PROTOZOA
FUNGI
PATHOGENIC ANIMALS
VIRUSES
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Viruses are considered to be nonliving
Infection of a virus can be broken down to the basics:
1.
2.
3.
4.
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Viral nucleic acid (either DNA or RNA) enters the cell
Viral nucleic acid is used to make proteins (enzymes)
Viral proteins take over activities of the cell to make more viruses
New viruses exit the cell through exocytosis or by rupturing the
cell
Retroviruses (viruses with RNA) mutate easily
The only proven way to treat most viruses is to allow the
body’s immune system to eradicate it
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Medicines may be prescribed to inhibit the virus’s ability to reproduce
OTC medicines can only treat symptoms of viral infections
BACTERIA
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Bacteria are classified in 3 ways:
1.
Function (aerobic v. anaerobic)
2.
Staining properties (Gram positive v. Gram negative)
3.
Shape/Size
Bacteria cause infection in 3 ways:
1.
Releasing toxins that damage tissues (Clostridium botulinum)
2.
Becoming parasites within cells (Midichloria mitochondrii)
3.
Colonize and take over health tissues (Escherichia coli, Actinomyces,
and Lactobacilli)
Bacteria are usually treated with antibiotics*
FUNGI
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Fungi in nature may have chlorophyll, but the ones the
infect humans do not
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Fungal infections are usually not detected until the fungus
has reached reproductive maturity
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Fungal infections will require multiple treatments with
anti-fungal medications
PROTOZOA
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Protozoa are like bacteria because they are unicellular but they
contain organelles (including a nucleus)
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There are 4 types of protozoa
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1.
amoebas (use pseudopodia for movement)
2.
Flagellates (use flagella for movement)
3.
Ciliates (use cilia for movement)
4.
Sporozoa (contain structures for burrowing into tissues)
Many protozoa use a vector to help in transmission between
hosts
Vector – a n o r g a n i s m t h a t c a u s e s d i s e a s e i n
another organisms (usually by transmitting
a pathogen)
PATHOGENIC ANIMALS

Often are called metazoa
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Signs/Symptoms of metazoan infection are caused by the
parasitic nature of the pathogen
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There are 3 different types of metazoa
1.
Nematodes (round worms)
2.
Platyhelminthes (flat worms)
3.
Arthropods (spiders and insects)
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Metazoa are often vectors
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Prevention of these types of diseases (and the diseases they
spread) is usually accomplished by eliminating the pathogen from
an environment
LEARNING GOALS

I can …
… describe each of the 5 pathogenic organisms discussed in
class
…compare and contrast how the different pathogenic
organisms are classified
…compare and contrast how the different pathogenic
organisms cause infection
…compare and contrast how the different pathogenic
organisms are transmitted from person to person
…compare and contrast how the different pathogenic
organisms are treated