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The oldest reference to paralytic poliomyelitis
is an Egyptian stone engraving over 3,000 years old. Cases of poliomyelitis
tended to be rare in ancient times because sanitation was poor. Infants
would build up immunity to polio by transplacentally acquiring maternal
antibodies. Exposure throughout life provided continual boosting
of immunity and thus paralytic infections were rare. With improvements
in waste disposal and the widespread use of indoor plumbing in the 20th
century, epidemics of polio began to occur with regularity in the developed
world. Babies were much less likely to be infected with polio and
gain protective immunity. As the children got older and began playing with
others, swimming in public pools, and going to school, they were more likely
to be exposed to the virus without having developed protective immunity.
Since
the exact mechanism of polio's transmission was unknown in the early part
of the twentieth century, many areas were placed under strict quarantine
when outbreaks were recorded. Fear and confusion resulted in mass exodus
from the city. One early popular treatment was for polio patients to spend
time in the mountains, breathe fresh air, and live in a stress free environment.Another
form of treatment for severe bulbar paralytic poliomyelitis patients was
the iron lung, developed by Dr. Philip Drinker at Harvard School of Public
Health.
(Picture taken from http://www.pbs.org/)
It
consisted of a rigid cylinder into which a patient could be placed, and
at short regular intervals negative and positive pressure would be applied
within the apparatus to mechanically compress the lungs and hence effectively
producing respiration. However, this was ultimately not a very pragmatic
solution since the patient would be entrapped in the machine.
A pragmatic and efficient solution did not arrive until Dr. Jonas Salk's
lab developed a vaccine in the 1940s based on a formalin inactived virus.
The vaccine was shown to be 70% effective and was approved in 1955.
(Picture taken from http://www.pbs.org/)
However,
at the end of April 1955, a large batch of poliomyelitis vaccine manufactured
by Cutter Laboratories in Berkeley, California, actually caused polio in
scores of children. The incident quelled public euphoria over the injectable
vaccine and resulted in a month-long suspension of the vaccination program
in the United States. This setback raised several issues regarding
the vaccine including safety and production procedure mandates. A
filtration step was then added to the production procedure to ensure that
the viruses in the vaccines were completely inactivated.
(Picture taken from http://www.pbs.org/)
In 1958, Sabin developed the Oral Polio
Vaccine based on an attenuated wild type poliovirus. The main difference
between the two vaccines was that the OPV produced by Sabin induces long-lasting
protective immunity of the gastrointestinal tract to all known forms of
poliovirus while the IPV produced by Salk induces a long-lasting systemic
immunity to all forms of the poliovirus.
Once the Sabin and Salk vaccines were
proven effective, the disease was rapidly eradicated throughout most of
the industrialized world. The economic effect has been enormous; it has
been calculated that the polio vaccine pays for the costs of its development
approximately every three weeks. The benefit to the United States alone
for this single breakthrough runs into the trillions of dollars.