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itself." "In addition he has an atypical form, which parenthetically is by far the
most fatal."
In London there has perhaps been less variability than elsewhere. Thus comparison
between the main symptoms, in 166 cases in 1921 and 315 cases in 1924,
shows but little variation. Furthermore, study has been made of the extent to
which cases of encephalitis lethargica give a history of contact with cases of influenza
or suspected influenza, in epidemic and non-epidemic periods. A Table has been
prepared on the lines of the Table (making similar enquiry as regards cerebro-spinal
fever and influenza) which appears in the annual report for 1916, p. 12. The results,
in the epidemic period in 1924 for encephalitis and influenza, roughly correspond
with those in the epidemic period, January-May, 1915, for cerebro-spinal fever and
influenza. In London, then, it seems that, while the superficial distinguishing
features of encephalitis may have undergone some variation between 1916 and
1924, the epidemic constitution of which encephalitis forms a part has, broadly
speaking, remained essentially true to type—plus 5a change plus c'est la meme chose.
The chart on p. 24 shows that prevalences of encephalitis lethargica have
shown a tendency during recent years to develop more especially at times when
influenza prevails.
From the epidemiological point of view the protean behaviour, as it has been
called, of forms of epidemic disease affecting the central nervous system has
been insisted upon again and again. Hecker, with his tabular statement
of contemporaneous epidemics, drove the argument home so far as the English
Sweats and other outbreaks of the 15th and 16th centuries were concerned;
it was hinted at by Sydenham, Willis and Huxham, in succeeding centuries;
and in our own time it has been emphatically insisted upon by Creighton.
Dr. Hall, himself one of the discoverers of the latter-day "new disease" (which he
prefers, by the way, to call "epidemic encephalitis"), writes: "There are those
who from an epidemiological standpoint would group together influenza, cerebrospinal
fever, poliomyelitis, polioencephalitis and epidemic encephalitis, as arising
from some common condition." He hints elsewhere that "epidemic influence"
was responsible for the similar grouping manifested at the time of the English Sweat,
400 years ago, when outbreaks of Sweat, Hauptkrankheit, cerebritis, encephalitis,
Hauptwehe and trousse galant, prevailed in various parts of Europe. England, at
that time, it is well to remember, tenaciously held to the belief that the English
Sweat was capable only of affecting those of the "Englische sort." So in like
manner, nowadays, in the statistical returns of the Ministry of Health, relating to
epidemic diseases occurring throughout the world, England and Wales stand
apparently pre-eminent in the matter of suffering from encephalitis lethargica.
Dr. Hall notes this, and he adds: "There seems no evidence except the official figures
to suggest that the disease has been more severe in this country than elsewhere;
indeed, judging from the literature the reverse seems more probable."
In discussing the Relation of Epidemic Encephalitis to other Epidemic Diseases,"
Dr. Hall writes: "The controversies which in the early days raged round its
relations to poliomyelitis have now subsided." He sympathetically adds: "They
were at that time very natural;" but, he says," as time goes on the difference between
the two diseases becomes increasingly marked. . . It is "in the varying
after results that the two differ so widely." He is referring, of course, to the "mental
and moral changes'' following in the wake of encephalitis which have been systematically
studied in the last few years. These, he thinks, give it a distinctive mark. He
points out, however, that "Cameron, from the clinical point of view, and Shrubsall,
from that of the school medical officer, have made it clear that many of these cases
are merely exaggerated examples of the "difficult child," and that firm and judicious
handling beings about marked improvement." It would be impossible to prove
that the particular type of difficult child in question had only been met with in
recent years ; indeed, it is recognised that children suffering from chorea not