Infectious Disease
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Transcript Infectious Disease
Disease
Disease - Any change, other than an injury, that
interferes with normal functioning of the body
Pathogen – a disease-causing microorganism
Infection – when a body is successfully invaded by a
pathogen
Infectious disease – a disease that can be transmitted
from person to person, or animal to person, or insect
to person, etc.
How do diseases spread?
It depends on the disease
Air, wounds, contaminated water, food, infected
animals, insects, sex, etc.
Germ Theory
Before the theory (mid-1800s), people believed that
disease was caused by bad luck or evil spirits
Germ theory states that microorganisms cause disease
Louis Pasteur – first scientist to create a vaccine
Anton VanLeeuenhook – invented the microscope,
could see microscopic organisms for the first time
Viruses
Virus – non-cellular,
non-living
Invade the host cells
(humans) and use those
cells to reproduce
themselves – CANNOT
do this without the host
Hard to “cure”, but
vaccines help to prevent
the disease
Bacteria
Single cells
Prokaryotes
Most bacteria are
harmless
Can cause disease by
killing your cells,
producing toxins, or
invading your cells like a
virus
Many can be killed with
antibiotics
Fungus
Mushrooms and molds are harmless examples
Most fungi are harmless
Athlete’s foot, ring worm and San Joaquin Valley Fever
are examples of fungal diseases
Protozoa
Single celled eukaryotes
Most common in humid
regions of the world
Malaria – caused by
Plasmodium (infects red
blood cells)
Hard to cure because
protozoa are similar to
our cells, so drugs that
kill them, also kill our
own cells
Helminths (worms)
Enter through human digestive tract or skin
Can be ingested: trichinosis (under cooked pork),
guinea worm disease (contaminated water),
Can enter through skin: schistosoma (schistosomiasis)
– through snail infested water, Filaria worms cause
elephantiasis – from mosquito bites
Classifying disease
Emerging – apparently
“new” diseases
Re-emerging – diseases
that have recently
increased in incidence
after a period of decline
Endemic – diseases that
have remained relatively
constant in incidence
throughout recorded
history
Emergin
g
diseases
Re-emerging
diseases
Endemic
Diseases
AIDS,
Cholera,
Ebola,
influenza,
legionnaire
disease,
lyme
disease
Tuberculosis,
malaria,
schistosomiasis
Pneumonia,
polio, guinea
worm
disease,
plague, strep
throat