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14
actually taken are not an important factor. So long, however, as the oysters from these dangerous
areas are allowed to be sold by ignorant or unscrupulous men, suspicion will rest upon all shipments
from the port." Study of the Report as a whole incidentally causes the reader to wonder how it comes
about that importance is still attached, perhaps more largely in America than here, to the healthy carrier
hypothesis.
Influenza,
A severe epidemic of influenza occurred practically throughout Europe towards the end of 1921.
In England the areas earliest attacked were certain parts of the West Riding of Yorkshire and of Nottinghamshire
and Derbyshire, where the epidemic began in the latter half of November ; other parts of these
counties were attacked about the same time as London, where epidemic influenza was not clearly present
until more than a month later. In the areas first affected the epidemic had practically run its course
before there was general incidence in the rest of the country. In London during November the mortality
from bronchitis was exceptionally high for the time of year, but this was accounted for by the
period of very cold weather which followed upon a warm and dry autumn. There were, nevertheless
signs and portents of the approach of influenza, sporadic outbreaks in the schools being observed from
about the middle of the autumn term.
It is of interest to note that in Franklin Parsons' paper* on the first four epidemics of the nineties
of last century, Yorkshire is mentioned as among the first areas affected in the great epidemic of 1891.
So far as may be judged from the mortality returns, influenza became epidemic in Yorkshire earlier
in 1921 than in any of the principal cities on the continent.
During the course of the epidemic, about 2,200 deaths in London, were attributed to influenza
and taking into account the deaths from complications it is estimated that not less than 5,000 deaths
were caused by the epidemic. This is the same as the similar estimate for the epidemic of FebruaryMarch,
1919. The two epidemics of 1918, were estimated to have caused 18,000 deaths in London.
The proportion of deaths due to pneumonia and bronchitis as compared with those certified as due to
influenza was greater in the 1921-2 prevalence than in any of the 1918-19 epidemics. The temperature
during the course of the epidemic was rather above the average, and therefore it is justifiable to assume
that the excess in mortality form these causes which, except in influenza epidemics,depend directly upon
low temperature, was the result of the epidemic alone.
The contrast in the age-incidence of mortality in the epidemic of 1919, and in that of last year
is remarkable : in the earlier epidemic the maximum mortality occurred at the ages between 25 and 35,
and at these ages the deaths stood out clearly from those at other ages, giving rise to the opinion that the
incidence among munition workers had been excessive and was responsible for this feature. In the
epidemic of 1921-2 the excess at ages 25—35 is practically absent, the age of highest mortality being
65—75, as in the epidemics of the nineties ; though it must be added that the excess at the higher ages
is nothing like as great as in those epidemics.

It would appear from the records of school attendance that the number of children attacked in
1921-2, was greater than in the winter epidemic of 1919, the percentage of attendance being particularly
low in the City, Stepney, Bethnal Green and Poplar. On the other hand the number of cases
of sudden illness attributed to influenza, in the streets, necessitating removal in the Council's
ambulances, did not exceed 25, the greatest number in any week being 13, in the second week of
this year. In the winter epidemic of 1919, there were more than 120 such cases, the maximum number
in one week being 32.
The
influenzal
group of
diseases.
Reference was made last year to the Ministry of Health Report on the great pandemic of 1918-19,
and to the description given therein of the "setting" of an influenza pandemic in the midst of " parallel
or allied clinical maladies" of nervous, gastro-intestinal and respiratory illnesses. The improved
facilities of recent years for dissemination of information with reference to such obscure epidemic prevalences
and " new diseases " have brought to light further instances of the truth of the observation made
last year that quite a revolution is being worked in regard to the epidemiology of diseases of the influenzal
group. As was stated in the Ministry of Health report" The admittedly vague concept of an 'epidemic
constitution' does indeed correspond to something in nature there really is a development
over a series of years of various clinical forms of infective disease, which tend to assume a generic
type and to prevail before and after an epidemic of influenza." In 1919 and 1920, it was, of
course, only possible to consider forerunners of the pandemic, now particulars are coming to
* Transactions of the Epidemiological Society, N.S., vol. xiii., p. 116.