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source. Again, some of these unrecognised cases were found
to have attended school, and in this way another channel by
which infection was spread was provided, and many schools
thereby became the foci of infection, rendering it necessary
to close class-rooms in certain Council and non-provided
schools, wherein it was evident infection was taking place.
The number of cases notified during each week and
month was fairly uniform throughout the year except during
August, though the usual rise occurred in the fourth quarter,
reaching a maximum in November. On referring to the
tables on pages 66 and 67 it will be noted that there was a great
reduction in the number of notifications received during
August, pointing to the influence of the schools as a factor in
the spread of the disease. There can be little doubt in my
opinion, that the schools are a very common channel for the
spread of this as well as of other infectious diseases.
That the closure of the schools during the summer
vacation, about the period of the ascending epidemicity of the
disease, is the cause of the decline in the attack rate, and not
(as is asserted by some) the annual exodus of children which
takes place during the summer holidays, is a fact that will be
apparent to any person who studies the question. Greater difficulty
is, of course, experienced in tracing the source of infection
in Scarlet Fever than in many other infections, but, after making
due allowance for this, the higher incidence of the disease
amongst children at school ages, and the effect which the
closure of the schools during the summer holidays exerts is not,
in my opinion, to be explained away by this annual migration.
Moreover the same decline in the incidence of the disease on
closure of the schools occurs in the provinces, where little or no
exodus of children takes place during the summer holidays.
The sources of infection were in 283 cases more or less
definitely associated with the schools. In 177 cases there
was a history of exposure to infection from a previous
case; 47 were "return" cases; 12 were infected outside the