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virus injected into the muscle. This event does not now happen in our clinics
since we adopted the subcutaneous method of immunisation. And finally,
certain forms of warts on children have been found to be caused by a virus
infection; which leads to the thought, could it be that cancer in older people
is caused by virus infections which we have not yet detected ?
POLIOMYELITIS
During the past few years there has been remarkable progress in out
knowledge of poliomyelitis. We know the disease is caused by a virus, one
of the smallest organisms known. For many years the only known method of
cultivating the virus was by injecting it into the brain of a living monkey; but
recently the bacteriologists have learned how to cultivate it on tissue-cultures
and in developing chicks in eggs. It has been found there are at least three
different species of virus, each one quite distinct in the illness it produces;
they are known as Brunhilde (type 1), Lansing (type 2), and Leon (type 3),
Each type produces a specific immunity in a person attacked, but the immunity
does not protect against either of the other types.
Epidemics.
Before 1947, poliomyelitis in this country was endemic; that is, odd cases
occurred here and there throughout the year. It is believed that the organism
mainly responsible was the Lansing (type 2) species; also that most people
received an infection from this organism in early childhood and acquired immunity,
but that a few were stricken with the paralysis in varying forms of
severity. However, in 1947 there was a tremendous epidemic outbreak of a
much more severe type, with frequent paralysis both of the skeletal muscles
and of the respiratory and swallowing mechanism, and many deaths. The
epidemic wave has been high in the autumn of every successive odd year from
1947, that is, in 1949, 1951 and 1953, and moderately high in the even years.
By far the commonest species now found is the Brunhilde (type 1). This
species seems mainly to have been responsible for the widespread epidemics
in the United States and in Copenhagen. In order of importance the main
killing infectious diseases are now tuberculosis, influenza, whooping cough,
and poliomyelitis. But poliomyelitis inflicts by far the greatest amount of
residual damage in the resulting paralysis and crippling.
Clinical Cases.
For convenience we divide the population who have been infected with
any of the types of poliomyelitis as follows:—
Group 1. Non-paralytic, where no residual paralysis has occurred.
(a) Silent immunising infection.
(b) Abortive type with fever.
(c) Severer type with neck stiffness.
Group 2. Paralytic, where paralysis has followed infection.
(a) Spinal type.
(b) Bulbar type.
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