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proven, unless it can be reduced to infinitesimal proportions by means of
the Schick test. We keep on talking about the drains which we
religiously test, and we think of the advance of sanitary science, but so
far as diphtheria is concerned, we are not advancing, we are going
back. We have at hand the means for cutting down the incidence of
the disease, but there is a reluctance in adopting this saviour of the
children, simply because it smacks too much of vaccination and smallpox.
Why we do this I do not know; it is something which no
"fellar " can understand.
To explain the Schick test: One-tenth of a cubic centimetre of
diluted diphtheria toxin is injected between the epidermis and dermis,
and this is followed by a small wheal or milk-white elevation around
the point of the needle. The reaction, of course, depends on the local
irritant effect of the diphtheria toxin. If the blood of the subject tested
contains no anti-toxin naturally, or in an insufficient amount for protection,
a positive reaction will appear in from 24 to 48 hours.
This reaction is characterised by a circumscribed area of redness
and slight infiltration measuring from one-third to two-thirds of an inch
in diameter; it generally persists for from seven to ten days, and on
fading shows superficial scaling and a persistent brownish pigmentation.
In order to distinguish the true reaction from false reaction which occurs
in a small percentage of older children and adults, a control solution of
diluted toxin heated to destroy specific activity is injected into the
opposite forearm at the time that the Schick test is made.
After three to five days, final readings are made as follows:—
1. Positive, if there is a definite well-pronounced red area on the
test forearm and no redness or pigmentation on the control forearm.
2. Negative pseudo if there is a fading brownish or reddish-brown
area of pigmentation not sharply circumscribed but equal in size and
similar in appearance on the two forearms.
3. Positive combined (positive) if there is a typical positive reaction
on the test forearm and a faded pseudo-like reaction on the control
forearm. Individuals exhibiting positive or positive combined reactions
should be immunised, either with diphtheria antitoxin or with toxinantitoxin
mixture (Diphtheria Prophylactic) the choice of immunising
agents depending on whether or not there has been recent exposure.
Ninety per cent. of all susceptible children can be immunised by
these injections. The protection thus afforded lasts for years and
possibly for life. The following are the indications for the use of the
method described.