Download Polio

Poliomyelitis
Polio is a highly infectious viral
disease
One In 200 infections results in paralysis, usually
of the legs.
In the 1930s a polio epidemic emerged in the US.
Although Polio isn’t the most deadly infectious
disease it terrified everyone
So why an epidemic?
•Around the 1900s nations cleaned up their water
supplies
•
http://www.museumofdisability.org/sitei
mages/media/MagAdMarchofDimes.jpg
So why an epidemic?
•Around the 1900s nations cleaned up their water
supplies
• Mothers used to pass antibodies to their children.
•
http://www.museumofdisability.org/sitei
mages/media/MagAdMarchofDimes.jpg
So why an epidemic?
•Around the 1900s nations cleaned up their water
supplies
• Mothers used to pass antibodies to their children.
•By the 1930s mothers no longer had those antibodies
to pass to their children since they had never been
exposed to the virus before
•
http://www.museumofdisability.org/sitei
mages/media/MagAdMarchofDimes.jpg
So why an epidemic?
•Around the 1900s nations cleaned up their water
supplies
• Mothers used to pass antibodies to their children.
•By the 1930s mothers no longer had those antibodies
to pass to their children since they had never been
exposed to the virus before
•THIS LEFT CHILDREN VULNERABLE
•
http://www.museumofdisability.org/sitei
mages/media/MagAdMarchofDimes.jpg
It was not just a disease of the poor!
http://img.dailymail.co.uk/i/pix/2007/12_03/polioDM_468x707.jpg
President Franklin Delano Roosevelt
This got peoples attention!
• “Iron lungs”
were used to
help patients
breathe if the
paralysis
spread to their
diaphragm.
Clearly a vaccination is in order.
BUT first what causes polio?
The Poliovirus (PV) Causes Polio
Poliovirus invading a cell
•The virus attaches to
specific cell-surface
receptors (Vpr)
Poliovirus invading a cell
•The virus attaches to
specific cell-surface
receptors (Vpr)
•It then enters the cell
through endocytosis
and releases its
genetic material into
the cytoplasm
POLIOVIRUS
PV enters the body through the
nose or mouth then lives and
multiplies in the human gut.
POLIOVIRUS
• During this stage the patient experiences flu like symptoms
such as:
– Headache
– vomiting
– fever
– Neck stiffness
– Pain in limbs
Next, the virus moves to the blood stream
where the immune system makes
antibodies to it and hopefully fights it off.
If the Immune system fails…
PV travels to the central nervous system and
attacks motor neurons which can result in
flaccid paralysis, muscle weakening or death.
BUT, thankfully the human immune system
is so good that it only causes paralysis in 1
in 200 cases!!
However it can still spread…
The poliovirus spreads through
infected feces or phlegm
Open sewer
The Virus Can
survive for up
to two
months
outside the
body!!!
To stop the spread of polio scientists
developed vaccines
• In 1955 Dr. Jonas
Salk produced the
first polio vaccine:
• A Killed virus
vaccine
• 70-90% effective
against all three
strains of poliovirus
In 1957 Albert Sabin developed a
live, attenuated vaccine
• Delivered orally
• provided longer
immunity
Mandatory Vaccinations eliminated
wild poliovirus infections from the U.S.
by 1979!!!
So What
Next??
1988 a global eradication plan was
put into action
•Lead by WHO, UNICEF, Rotary
international; and the US centers for
disease control
The number of cases dropped by
over 99% in the 20 years! (WHO)
20 million volunteers
have vaccinated 2
billion children in
200 countries!
•
http://www.africagoodnews.com/development/health/2227-new-hope-for-polioeradication.html
And It Only takes a
few drops!
But there is still much work to be
done!
• The eradication campaign has encountered
many set backs
– Especially in the countries that remain endemic
• Polio remains endemic in only four nations:
– Pakistan
– Afghanistan
– India
– Nigeria
The Numbers Today