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outbreak of 1916, almost contemporaneous with the famous New York outbreak
of "poliomyelitis" ; and, finally, he attacks the problem of the two types of affection
of the nervous system, "polioencephalitis" and "lethargic encephalitis," occurring
in 1918-19, these two designations being at first, as he notes, " used as probably
interchangeable terms."
The recrudescences of "encephalitis lethargica" of 1920 and of 1923-24 were,
he finds, associated with "well marked irritative symptoms, which were usually
slight or absent in the cases occurring in the years when the cases were fewer."
"The only result of this was that the clinical picture tended to become confused,
and meningitis, pneumonia, insanity, acute chorea, cerebral haemorrhage or abscess,
and influenza, among others, are among the names which might ultimately obscure
the presence of encephalitis lethargica or be mistaken for it."
The similarity of experience, in these epidemics of the central nervous system,
as studied epidemiologically in Glasgow and in London, certainly seems to confirm
the advice given by Sydenham, " If any one ask how he is to fish out the species
of a particular fever let him choose for his field of observation some large and
populous place." In the outbreaks of 1920 and 1923 in Glasgow, as in some parts
of America and elsewhere, it is noted there was a "substitution of symptoms of
cerebral irritation for somnolence or lethargy in the initial stages"; this, however,
as already stated last year, was not a very marked feature in London, and analysis
of the commoner symptoms in more recent prevalences confirms this impression.
Dr. Chalmers studied the question of "cases following or associated with other
illnesses," a subject enquired into also in London, both in connection with cerebrospinal
fever and encephalitis lethargica. A map is given by Dr. Chalmers showing
topographical distribution of cases of encephalitis lethargica in Glasgow. Dr. Shrubsail
has for some years past been engaged in studying the topographical distribution
of heart cases among children in the special schools of London, and has found evidence
of a tendency to concentrate in the river valleys. (See p. 126.) With a view to
comparison between the grouping of these cases and that of encephalitis lethargica,
the London cases of both diseases are shown in the map on p. 125.
The lesson to be learnt from these studies of Dr. Chalmers is that "if we are
to accept the succession of detached outbreaks, as linked up with each other through
a chain of sporadic cases, the field of enquiry cannot well be limited to epidemic
periods alone. Nor can it, with much hope of advance, be limited to the few clinical
types, which, by reason of their gravity, compel attention." Dr. Chalmers is, indeed,
justified in claiming recognition of those "gradations, modifications, affinities,"
which Creighton insisted upon in studying epidemic diseases. It is the method of
Hippocrates and Sydenham; and it is one which complies with the demand of
Heraclitus, that men should seek the sciences not in their own narrow worlds but in the
wide one.