London's Pulse: Medical Officer of Health reports 1848-1972
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Hints from the Health Department. Leaflet from the archive of the Society of Medical Officers of Health. Credit: Wellcome Collection, London
London County Council 1925
[Report of the Medical Officer of Health for London County Council]
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or dryness of the throat, followed in most cases by double vision and somnolence. In
the acute stage there is marked weakness, fever, stupor, often alternating with
nocturnal delirium, difficulties in speech and spasmodic twitchings of the limbs and
face. In some cases there are no localising symptoms, in others there are squints,
double vision, difficulties in accommodation of the eyes, facial paralysis, and paralysis
of the tongue and gullet. Death is due to paralysis of the nervous respiratory
centres. Severe cases lie in bed with complete lack of expression and, though
irritable when aroused, quickly relapse. Stupor may last only a day or so, or may
persist for weeks. Some cases show only muscular spasms or fine twitchings, of the
abdominal muscles. In 1922-24 rather more cases showed brain affections with
epileptiform fits, maniacal outbursts or insomnia.
There are a certain number of mild or abortive cases, and experience has shown
that some can pass entirely unrecognised until the onset of certain sequelae of the
disease. Naturally many of the milder cases have been called "influenza," while in
others the disease has either occurred simultaneously with, or has so closely resembled
scarlet fever or diphtheria, as to have originally been diagnosed as such. Some
cases with prolonged depression and stuporous conditions have at first been thought
to be typhoid fever, while rarely, a case with marked respiratory disturbance, has
been thought to be acute tuberculosis.
Incidence
and
mortality.
Encephalitis lethargica has been a notifiable disease since the beginning of 1919, but it is evident that only a proportion of the cases have been recognised in the early or acute stage. In London the numbers notified are as follows:—
| Year. | Total notified cases. | Number of these of school age (3-14). | Year. | Total notified cases. | Number of these of school age (3-14). |
|---|---|---|---|---|---|
| 1919 | 86 | 15 | 1923 | 101 | 17 |
| 1920 | 149 | 41 | 1924 | 610 | 173 |
| 1921 | 243 | 59 | 1925 | 305 | 47 |
| 1922 | 72 | 17 | |||
| Total | 1,566 | 369 |
Full information is not available as to all these cases, and it is probable that
there were at least as many more cases that were unrecognised. The figures as to
age incidence show that persons of any age may be attacked, but that the heaviest
rate is between 10 and 30. In London between 1919 and 1925 the numbers notified,
as to which the information of age and onset was available, were:—
Ages 5 6-10. 10-20. 20-30. 30-40. 40-50. 50-60. Over 60.
Notified cases 81 120 365 232 196 186 138 86
The case-mortality rates quoted have ranged from 15 per cent. to 53 per cent.,
that in London for notified cases to the end of 1924 being 30.2 per cent. In 1925
the rate for verified cases was 45.3 per cent.
The following table shows the distribution of actually confirmed cases, and the number of deaths in the different age groups, occurring within the scope of the analysis —i.e., from January to September, 1925.
| Ages. | —5. | 5—15. | 15—25. | 25—35. | 35—45. | 45—55. | Over 55. | Total. |
|---|---|---|---|---|---|---|---|---|
| Cases | 15 | 31 | 43 | 17 | 26 | 26 | 21 | 179 |
| Deaths | 14 | 14 | 4 | 11 | 16 | 17 | 81 |
No special racial incidence has been noted, while all social classes of the community
have been affected. The disease has been, on the whole, distinctly more
prevalent in the colder months of the year, the curve of incidence rising in the autumn
and falling in the spring. This feature has been noted not only in London, but
throughout the British Isles, Western Europe and North America.