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(Karl
Landsteiner http://encarta.msn.com
)
Poliovirus was discovered by Karl Landsteiner
in 1909. Before the discovery of the infectious nature of the disease,
the paralytic aspect was considered to be its characteristic feature, as
documented by the denomination "infantile paralysis." Although its infectious
nature was long hypothesized, Ivar Wickman was the first to clearly show
the infectious nature of polio after an epidemic in Sweden in 1905.
Landsteiner and his assistant E. Popper
injected intraperitoneally suspensions from the spinal cord of a 9-year-old
boy into rabbits, guinea pigs, mice and monkeys. Only the monkeys showed
signs of disease. Both displayed severe degeneration of motor neurons and
inflammatory cell infiltration in the spinal cord. no bacteria were found,
and the nervous system changes resembled those of rabies, so a viral etiology
of the disease was suggested. Lansteiner sent fragments of a spinal cord
from a 13 year old child afflicted with poliomyelitis to the Pasteur Institute
in Paris. In collaboration with C. Levanditi the infectious agent was shown
to be a filterable virus that could spread along nerves and be transferred
between monkeys.
The discovery of the virus causing poliomyelitis
was immediately accepted and a group led by S. Flexner at the Rockefeller
Institute took over the research. In monkey experiments, it was observed
that polio could be an airborne infection, spreading to the nervous system
along the olfactory route. Unfortunately, this discovery led to the neglect
of epidemiological studies showing poliovirus was transmitted as a gastrointestinal
infection.