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for attributing the spread of scarlct fever or diphtheria to this
cause to any extent. Definite eases of school infection do occur,
but not to an extent sufficient to justify the popular opinion that,
if a school child has contracted either of these diseases, he must
have caught it at school—and if a child under school age suffers,
he must have contracted it from his brother or sister who attends
school. It is conceivable that, although school attendance does
not cause actual infection to any extent, it might still result in the
production of immunisation amongst the scholars. There is
every possibility that a child suffering from diphtheria in the early
stage and attending school, even though not infecting any
individual child, might give off small doses which will act as part
of the series of sub-infective doses which will immunise the contacts.
There is this difference, however, that whereas a ease directly
infected required only one, probably relatively massive and rapid,
infection to succumb, the proccss of immunisation is the result of
a long series of small doses. School attendance might result in
these doses being obtained at shorter intervals and so the resulting
immunity appears at an earlier age. By itself though, school
attendance has probably little to do with the production of Schick
negative reactors. This suggestion is supported by the following
observations :—
Dudley in the No. Ill of Special Report Series of Medical
Research Council, "Spread of Droplet Infection in semiisolated
communities," records how, when dealing with the
infections in the Royal Naval School at Greenwich, at which there
are residents and day boys, if diphtheria occurred in the community,
the carrier rate rose with a rise in the immunity index. This rise,
however, occurred much more markedly in the residents than
amongst the day boys, the explanation being that there was more
time afforded in the dormitories than in the classrooms, to inhale the
necessary amount of diphtherial material to effect these reactions.
"On the Schick and Dick Tests in Diphtheria and Scarlet Fever"
from the Eighth Annual Report of the Scottish Board of Health,
1920, page .5, par. t (b), reacts :—
" In Aberdeen, 708 children from west-end schools,
children from middle class schools and KM children from cast-end
schools were tested. It was found that, of the west-end school
children 55G or 78-5% were Schick-positive : of the middle class
school children 235 or 62-5% were Schick-positive; while of the
east-end school children 126 or 31 -2 were Schick-positive.
A possible and probable explanation of the lessened susceptibility
of the poorer classes is that, the more crowded the
conditions under which they live, the more likely they are the
obtain minimum doses of diphtheritic infection, and to develop
sufficient antitoxin to prevent them from actually contracting the
disease."