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The first notable increase in the number of notifications began on August 16th, and was
maintained until October 11th. The first sustained rise in the weekly mortality began one week
later, on August 23rd, and came to an end about a fortnight earlier in the last week of September.
The degree of correspondence in the weekly incidence accordingly affords some grounds for
regarding the notified and fatal cases as belonging to the same aetiological group. The patients
notified fell into the following age periods:—
Age period in years Under 1. 1 to 2. 2 to 5. 5 to 15. 15 to 25. 25 to 45. 45 and upwards.
Number of cases 184 154 85 30 23 60 33
The figures do not represent the true age incidence of diarrhoea, since young children are
more likely to receive medical attention and so to be notified than older persons, who, except in
severe or persistent cases, generally forego medical advice, and are content to purchase a diarrhoea
mixture from the chemist. At the same time the notification of 83 cases between the ages of
15 to 45 has served to indicate the fact that epidemic diarrhoea is not confined to infants and
young children except in a fatal form. The Table of deaths from non-notifiable diseases on p. 18,
shows that whereas 81 deaths from diarrhoea and enteritis occurred in children under the age of
5 years, only 1 death occurred in the age period 5—15 years. As in the case of measles such
figures illustrate the age of liability to death, without throwing any light on the question as to the
age of greatest liability to attack. Children are more susceptible in both senses, but there is
published evidence to show that adults also suffer in large numbers from non-fatal attacks, and
that epidemic diarrhoea is not likely to be prevented by measures which are limited to the control
of the disease in infants.

It has been suggested that summer diarrhoea is an infectious disease, spreading from the sick
to the healthy, but the evidence in favour of this assumption afforded by the occurrence of more
than one case in the same house, should not be pressed unduly As examples of non-infectious
ailments which frequently attack several members of the same household, malaria and chillblains
may be mentioned. In favour of case to case infection attention may be drawn to the following
Table, which shows that when multiple cases occurred in the same house or household, an interval
of 3 to 14 days elapsed in many instances between the primary and secondary case.
Interval between First and Second Case,
Number of days Less than 3. 3 to 7. 7 to 14. 14 to 28. 28 to 56. 56 and upwards.
Number of instances 17 19 10 18 11 7
It will be understood that the intervals in the above Table do not represent minimum
incubation periods, since the cases were nursed at home and remained infectious, if the disease is
in fact infectious, throughout their illness.
In 28 of the 66 houses in which multiple cases occurred, persons aged 5 years and upwards
were attacked. On the assumption that the disease is infectious, the primary case might be
expected to occur in the majority of instances in young children who suffer in greater numbers,
and whose habits in such an ailment should render them a more effective source of infection.
The histories of these 28 houses, however, shows that only 12 of the primary cases occurred in
children under 5 years as against 16 primary cases in older persons. Of the primary cases in
young children, 10 occurred in infants under 2 years of age; of those in older persons 10 occurred
in patients aged 16 years and upwards.
The following Table shows the proportion per cent. of 392 houses where single cases of
diarrhoea occurred, and of 66 houses where multiple cases occurred in connection with which
conditions presumably favourable to the origin and dissemination of diarrhoea were noted:—