Abstract
Having in view the difficulties which arise in
diphtheria immunisation, this thesis will attempt to show: -
(1) a comparison between different immunising agents,
especially in connection with results and reactions.
(2) a consideration of questions of immunity, etc.
which may arise in this investigation.
(3) Any special feature of interest. Many have been
noted. In most cases this will be remarked upon.
(4) Any conclusions which may be drawn from this work,
as to the most convenient practical means of
carrying out diphtheria immunisation.
The word 'practical' is of some importance, as this thesis
is not intended to deal with more than this aspect of the
work. The Schick Test is taken as a reliable index of
immunity. There are many references in the literature to
Diptheria in 'S -' individuals. Moloney and Fraser
report cases which were 'S -' with less than 1/50 A.T. units
per cc. of blood, but clinical workers are agreed that for
their purpose it is a satisfactory test.
Joe describes it as a 'satisfactory guide'.
Parrish and O'Kell agree that the 'S -' state is more or
less permanent. Harries22 in 1930 asserts that "no 'S -'
person has ever had clinical diphtheria ". Bousfield
in presenting the case for Schick testing as a routine
measure describes a 'S -' state as a "training in antitoxin
production ", the real basis of active immunisation.
Rhoads is of the opinion that impotent toxin and bad
technique is the cause of 'S -' reaction in susceptible
individuals. The work of McLeod, and others, in Leeds
helps to explain the discrepancies in the test, by their
differentiation of the 'mitis' and 'gravis' type of
organism. Parrish and Wright in 1935 report several
small epidemics of diphtheria in 'S-7 individuals. The
epidemics occurred in a residential school, an orthopaedic
children's hospital, and a general hospital. They noted
that the cases were all due to the 'gravis' type of
organism. Those occurring in 'S -'s were all mild cases
clinically and recovered completely without complications.
(These cases were both immunised and natural 'S-'s.)
In the Orthopaedic Hospital mentioned, the carrier
rate for 'gravis' organ isms was 40% -- the patients here
were immunised as a routine. Dudley, May and O'Flynn
describe an epidemic due to the 'gravis' organism in the
Greenwich Hospital School. The cases were mild and often
'unrecognisable clinically'. The school consists of
900 boys and it kept at a 90% 'S-' level. They are of
the opinion that immunisation prevented an outbreak of
severe diphtheria, such as has recently occurred in the
North of England. It need only be said that a test which
indicates that a person will only suffer from a mild
disease instead of a severe one, with a high mortality
rate, is of great value.
One seems justified, therefore, in relying on
skin tests in judging the efficacy of an immunising agent
or method. In the actual employment of immunisation in
a Public Health Department, toxin titration of the blood
is not practicable.