Download Infectious Disease

Infectious Disease
40-1
What is Disease?
• Tell me what you think…
What is Disease?
• Disease
– Any change in the body, other than injury, that
disrupts the normal functions of the body
– Disease has many causes
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Bacteria
Viruses
Environmental Factors (cigarette smoke, pollution)
Genetics
Koch’s Postulate
• Koch said:
– Disease is caused by
microorganisms and
NOT by curses, evil
spirits or night vapors
– Yes, for thousands of
years, people believed
that diseases were
caused by those
things.
Infectious Disease
• Infectious = can be passed from person to
person
• Pathogens
– Cause disease
– EX:
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Bacteria
Viruses
Protists
Worms
Bacteria
• Single Celled living organisms
– Asexual reproduction
– Multiply by themselves
• Can easily be seen with a microscope!!
• Live & breed in warm, moist environments
• Prokaryotes: no nucleus
Bacteria and Humans
• Most bacteria = harmless
• Good for humans!
– many places on our bodies
– Intestines…digestion
Bacteria as Pathogens
• Bacteria as Pathogens
– Break down tissues
– Release toxins
– EX:
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Streptococcus (Strep Throat)
Diptheria
Botulism
Anthrax
E. coli (found in food)
Bacteria
Treatments for Bacterial Infection
• Antibiotics
– Kill bacteria, but not body
cells
– Interfere with the cellular
processes of the bacteria
– One antibiotic will kill
many different kinds of
bacteria
– Examples: Penicillin,
Amoxicillin
Virus
• 1000 times smaller than
bacteria!!
– Cannot be seen with a
microscope
• Cannot live or reproduce
on their own
– Must invade a host cell
– Contain RNA or DNA but
none of the equipment to
reproduce
Virus
• Pathogenic
• Mutate often
• Examples:
– Common cold
– Influenza
– Smallpox
– Warts
– HIV
Virus
Treatments for Viral Infection
• Best treatment:
– Rest
– Water
– No help from Doc!
• Antibiotics are NOT
effective against
viruses because
the virus live within
your own body’s
cells.
Why you feel sick when you have
an infection
• Symptoms caused by your body’s
response to the infection
– Fever
• kill the pathogen
– Vomiting, Runny nose, coughing
• physically remove the pathogen
– You feel tired because your body is working
overtime fighting the infection
In Review
• An Infectious Disease is
– Disease that can be passed from person to
person
• A Pathogen is
– A disease causing agent
• Bacteria
– Single-celled living organisms
– Killed by Antibiotics
• Virus
– Tiny particles, need host cell in order to
replicate
– Antibiotics are INEFFECTIVE