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Transcript
31.1 Pathogens and Human Illness
KEY CONCEPT
Germs cause many diseases in humans.
31.1 Pathogens and Human Illness
• 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
31.1 Pathogens and Human Illness
• 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
31.1 Pathogens and Human Illness
• Disease-causing agents are called pathogens.
• What would happen if pathogens were eliminated?
– We wouldn’t get sick
31.1 Pathogens and Human Illness
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”
31.1 Pathogens and Human Illness
• 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
31.1 Pathogens and Human Illness
• Fungi can be multicellular or single-celled.
– take nutrients from host’s cells
– occur in warm and damp places
Ex: Athlete’s foot, yeast, mold
31.1 Pathogens and Human Illness
• 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
31.1 Pathogens and Human Illness
• Parasites are multicellular organisms.
– grow and feed on a host
– possibly kill the host
Ex: Heart worm
Round worm
Elephantiasis- mosquitos
31.1 Pathogens and Human Illness
• 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
tick
Ex:
Lime Disease- ticks
Malaria- mosquito
West Nile Virus- mosquito
Rabies- rabid animal
HIV- infected person
31.1 Pathogens and Human Illness
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
31.1 Pathogens and Human Illness
• Different pathogens cause common infectious diseases.