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41
It would appear that weather conditions (or "season") play
some part in determining the onset of these outbreaks. I
know of no record of any such outbreak which did not begin
in the Autumn or Winter of the year. During the Finchley
outbreak the daily ranges of temperature were excessive, and
varied from 6 degrees to 19 degrees F. The atmosphere was
frequently almost, if not quite, saturated with moisture, and
frequent drizzly rains and mists prevailed. On the other hand,
on the 15th and 16th of January, when many of the first cases
were infected, the weather was bright and fine. The weather,
therefore, during the period of the outbreak, was very
favourable to chills and sore throats; but it does not, of course,
afford any sufficient explanation of the fact that the cases
were, in the first place, mainly restricted to Finchley, and, in
the second place, that they occurred almost exclusively amongst
the customers of a particular milk supply.
In these milk outbreaks there are always a few cases
occurring in households which are not served by the recognised
infected supply. This circumstance does not necessarily prove
that more than the one supply is affected; for the other cases
can be accounted for by the practice amongst milkmen to
borrow or purchase milk of each other on their rounds, by
the householders themselves buying other extra milk
occasionally in the mornings, by the fact that the disease
is doubtless communicable from individual to individual
(quite apart from the milk), and by the circumstance that
there are usually at the same time cases of ordinary sore throat
not due to milk (but most of which are ascribed to milk)
during the prevalence of such an epidemic.
The Measures taken to trace the source of the infection
and to deal with the danger may be classified as follows:—