View report page

104
(2) Conditions favouring spread of the disease either by
lowering the natural resistance of the body, or by increasing
the opportunity for transmission by direct personal infection.
(3) Occasionally but rarely, outbreaks of the disease
have been caused by infected food, principally by milk infected
with the diphtheria germ.
The Schick Test.
This test is based on the fact that newly-born infants are
immune to diphtheria for the first few months of life. This natural
immunity is rapidly lost up to the fourth or fifth year, after which
it again begins to be gradually recovered. The highest incidence of
mortality occurs, therefore, in this period, and although older
children and occasionally adults are liable to be attacked, and in
some cases with fatal results, it is amongst the younger children
that infection is most rapidly spread and with the greatest risk of a
fatal termination. The Schick Test, discovered by Professor Bela
Schick, of Vienna, in 1913, and called after the name of its discoverer,
consists of the injection of a minute measured dose of
diluted diphtheria toxin into not under the skin of the left fore-arm.
If the person injected has no natural antitoxin in his blood or an
inadequate amount for his protection, a positive reaction follows,
which is indicated by a small area of redness at the site of inoculation
in 24 to 48 hours. This is an indication of lack of immunity or
of the presence of insufficient anti-toxin to neutralize the trace of
toxin injected. The test is a simple and very sensitive one, and
therefore extremely useful for application to a community to
differentiate the immune from the non-immune.
It is the usual routine to apply a control test by injecting a
similar amount of sterilized toxin into the other fore-arm of the
person tested.
The technique is very simple and has been greatly improved
in the light of earlier experience of its use. In the hands of skilled
operators and observers, there is no danger and the results are
invariably of a most satisfactory character.
The Schick test, although comparatively new to this country,
has been largely employed in America, and in 1922 Dr. Park, of
New York, states that no ill-effects had followed its application
and the subsequent immunisation by toxin-antitoxin of 100,000
school children. Since then it is stated on high authority that
" almost a million inoculations in New York without the slightest
distress, and hundreds of thousands elsewhere in the United States,
should be sufficient evidence as to the safety of the method and as
to its great desirability."
Use in Great Britain.
The Schick test as to diphtheria susceptibility was in the earlier
days in this country restricted to its action as a test without attempting
active immunisation. During the last four years, however, an