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22
Enquiries made of practitioners ten days later showed a sudden drop
in the number of new cases of tonsilitis, which had by that time—so far as
could be ascertained—entirely ceased; there was moreover no recurrence of
the condition, and no further cases of scarlet fever associated with milk
from dairy X were recorded. These facts in themselves confirmed the
deduction which had been made from the data available, linking the outbreak
with this particular milk supply.
Two cases throwing some light on the relation of the infection to the
milk supply may be quoted. One boarder at school A developed tonsilitis
after having been isolated for twelve days from all known cases; this appeared
to eliminate personal infection; during that period he had been receiving
unboiled milk.
In another case a child developed symptoms and signs identical with
those of others affected during this outbreak, but the milk—which was taken
unboiled—came from a small milkshop appearing, at first sight, not to be
connected with the suspected milk. Enquiry showed, however, that this
milkshop did, in fact, receive its milk from dairy X.
There was some indication in the schools concerned of the grouping
of cases between certain dates. the clusters of cases of tonsilitis in schools
A and B corresponding closely in date. This would suggest an intermittent
infection of the milk, a hypothesis which would fit in with the suggested
method of infection.
So far as could be judged, personal case-to-case infection played only a
small part in the spread of the outbreak.
I wish here to refer to the prompt way in which the firm of dairymen
concerned dealt with the problem. Every request was at once and unhesitatingly
complied with, and the rapid cessation of the outbreak was due
to their willing and thorough co-operation.
Nature of the infection.—It is of some interest to speculate whether
the outbreak was, in fact, one of mild true scarlet fever, of some acute
infection closely allied to, but not identical with, scarlet fever, or of an
acute tonsilitis with "septic" rashes. A certain number of the cases were
indistinguishable in every way from typical scarlet fever. The cases admitted
to the Borough (Fever) Hospital, on notification as scarlet fever, were for
safety treated in isolated cubicles, so that they were not submitted to the
practical test of exposure to cross-infection. A case was however reported
of a child from one of the schools in question, with a home away from
Croydon, being admitted to a large fever hospital with signs accepted bv the
resident medical officer as being typical of scarlet fever, and re-developing
these signs, in a scarlet, fever ward, at the end of a week. This would
suggest that the condition, while clinically distinguishable from scarlet
fever in certain cases, did not protect against the ordinary form of the
disease.
It is not clear that Scarlet fever is a completely specific disease. It
is associated with infection by a hemolytic streptococcus, but it would be
quite reasonable to suppose that several allied strains of streptococci could
give rise to several allied forms of "scarlet fever," which might possibly
not be mutually protective against each other. This would afford one explanation
of the occasional "relapse" which, even with the greatest care,
occurs from time to time in scarlet fever wards; although there is no doubt
that genuine relapses can be experienced apart from this.
In the present instance the case is impossible of proof, but it seems a
plausible and likely view that the milk had been infected by a streptococcus
giving rise to a mild form of infection which it would be reasonable, in view
of its manner of onset, symptoms and causes, to call a mild form: of scarlet
fever, rendered somewhat atypical through the medium by which the infection
was conveyed. Similar aberrant types have been not uncommon in
milk-borne outbreaks where the infecting agent was clearly suffering from
ordinary scarlet fever.