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24
polioencephalitis should be included with it. In the succeeding years some of the
cases notified in London under these three heads were found at times to merge
somewhat confusingly into one another, and this same phenomenon was occasionally
observed, in rural areas also, by medical inspectors of the Local Government Board.
In the Spring of 1918 the " new disease," which it is now the fashion to term
"encephalitis lethargica," and which had been given this name, in 1917 on the
Continent, by Yon Economo of Vienna, came under notice here. It is becoming
recognised, nowadays, that any phase which may be assumed by influenza is apt
to be described as a " new disease "—men's memories in any case being short, and
their eyes being especially blinded at the present time in the dazzling light of so many
recent discoveries. On the advent of " encephalitis lethargica," really an old foe
with a new name, as Crookshank has clearly shown by study of the records, it was
described as an " obscure disease " by the cautious, and as " sleepy sickness," by
the man in the street. Some said it was " botulism," some " solanism," but after
these hypotheses had been criticised and abandoned, it was found convenient to adopt
Von Economo's designation, " encephalitis lethargica," since there was good reason
for holding it to be encephalitis, and lethargy was at the time, at any rate, quite a
prominent symptom. As Walker Hall of Sheffield has observed, it was " unfortunate
so much prominence should have been given to a single symptom, which may in
some instances be entirely absent." The " new epidemic disease " was, however,
duly declared notifiable, and there followed in 1920, 1921 and 1922 a decline in the
familiar poliomyelitis, polioencephalitis, and cerebrospinal meningitis, a well marked
prevalence of encephalitis lethargica becoming officially established in London
between 1919 and 1921.
In discussing "The influenzal group of diseases," in the annual report for 1921
(p. 15), it was stated that " while epidemiology cannot fail to take account of years
in which influenza prevails in pandemic phase, note must also be made of years
preceding and following the pandemic years, which also bear the impress of the
' influence' though in considerably modified form; and, thereupon, it may be
inferred with some show of probability, that at the midpoints between one pandemic
and another, i.e. in the troughs of the pandemic waves, the influence is also there,
but is so to speak in mufti,exhibiting mainly its immunising effects, and thus appearing
to play a far less important part than it assumes when the population has become
susceptible to influenza in pandemic phase."
Reference to the Table on p. 30 will show how the various notifiable diseases,
referred to above, comported themselves during the years 1913.23 ; cerebrospinal
fever predominating in 1915 ; poliomyelitis relatively high in 1913 and 1916 ;
encephalitis lethargica high in 1921 and again at the present time in 1924. When
"influenza," so called, began markedly to claim attention in the autumn of 1923,
pneumonia and bronchitis deaths also increased. In March, encephalitis lethargica,
too, became prevalent. " Drowsiness " had been noted by Franklin Parsons as an
occasional symptom of influenza in his report on the outbreak of 1889.90. In the
encephalitis of 1921 lethargy had been as already remarked an obviously recognisable
symptom; but lethargy has since 1891 shown a tendency in many instances to
be replaced by, or to alternate with, insomnia. The designation " sleepy sickness,"
it must be agreed, is unsuitable for a disease of which a prominent symptom
may be sleeplessness.
The " new disease " was now fairly in the limelight and its vagaries were carefully
scrutinised by many pairs of eyes. Walker Hall, one of the two earliest writers
upon it in 1921, and the author of the Lumleian Lectures on the disease, before
the Royal College of Physicians in 1923, pointed out (Lancet, 29th March, 1924)
certain aberrant features presented in recent cases : the intractable insomnia, the
"occupation delirium," attacks of dyspnoea, the "abdominal myoclonus," the
weakness of eye movement and consequent disturbance of vision."
It is from America, however, the land which at once accords to anything novel