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83
numbering 548. In Hampstead, where diphtheria of an unusually severe type was
prevalent in 1921, 826 examinations were made, giving positive results in 158 cases,
the total notifications in the year being 408. Several examinations are, of course,
made for one case, and the figures are only adduced to show how greatly the proportion
of positive results varies, and the differing extent to which recourse is had
to bacteriological methods by practitioners in different areas. The medical officers'
reports show that rather more than 10 per cent. of the cases notified are subsequently
found not to be cases of diphtheria.
The diphtheria attack-rate in London during 1922 was 3.4 per thousand of
population ; in 1921 the rate was 3.6 and in the ten years 1911-20 the average was 2 0.
The London rate in 1922 was considerably higher than that in any of the other
great towns in England and Wales. In view of the fluctuations in incidence from
year to year comparison is best made of average rates over a series of years; taking
therefore the sixteen towns in the rest of England and Wales which in 1921 had a
population exceeding 200,000 it is found that in four of them, namely, West Ham,
Cardiff, Stoke-on-Trent and Portsmouth the London rate of 2.0 for the ten years
1911-20 is exceeded, the rates ranging from 2.1 to 3.1. The towns with lowest
rates are Leicester, Manchester, Salford and Newcastle ranging from .9 to 1.2 per
thousand.
The position of London with regard to scarlet fever in the same ten years is
rather better, there being eight towns of the sixteen with higher rates of incidence;
the lowest rates are found in Bradford, Hull, Nottingham and Leeds, from 1.7 to2.6
per thousand; and the highest in Salford, Liverpool, Cardiff and Birmingham,
ranging from 3.8 to 4.8 the London figure being 3.1.
The severity of an epidemic prevalence appears to be determined by the extent
to which the population is immunised by recent attack; thus in 1914-5 diphtheria was
very prevalent in Stepney, but not in the neighbouring borough of Islington, and
with a smaller population Stepney at that time had nearly twice as many cases.
In the epidemic of the past two years the position was entirely reversed. Islington
suffering earlier and more severely than Stepney. It is not improbable therefore
that London has in the past two years paid the price of several years of relatively
low prevalence.
As stated above the notifications do not form an altogether satisfactory guide
to the general trend of diphtheria incidence over a series of years, the greater use of
bacteriological methods in diagnosis tending to overstate the incidence in the more
recent years. This difficulty does not affect the mortality rates. In the Annual
Report of the Medical Officer of 1914 the annual mortality from diphtheria in London
since 1858 is shown in the diagram facing page 16. The diagram shows that the trend
of the death rate was downward from 1859 to about 1872, thereafter there was a
remarkable increase, to a maximum in 1893, followed by a decline to a minimum
about 1913. From then up to the present time there has been a continuous increase,
and in the last two years the death-rate has reached a figure above that of any year
since 1902. The upward trend of recent years is not apparent in the similar rates for
England and Wales as a whole, but in the course of the period of comparison there
are other groups of years in which the London death-rate shows divergence from that
of England and Wales. The periods of maximum and minimum incidence nevertheless
approximately coincide.
In the report of 1921 (vol. III., p. 47) analysis was made of 6,973 bacteriological
examinations in connection with the occurrence of diphtheria in schools during the
period April 1921 to March 1922.
In the last nine months of 1922, 3,866 examinations were made of throat and
nose swabbings from 3,325 school children with the following results:—
Negative in 3,323 examinations of 2,966 children. Diphtheria bacilli found in
303 examinations of 158 children, or 5.3 per cent., and suspicious organisms reported
in 240 examinations from 201 children or 6.6 per cent.
The bacteriological
diagnosis of
diphtheria
carriers.