substance is in the human body the material cause of epidemic Summer Diarrhoea."
The development and multiplication of the micro-organism depended on a high
temperature, not in the air itself, but in the superficial layers of the soil.
The rise in the diarrhoea death rate does not begin until the average weekly
temperature of the thermometer (suspended in an iron tube 4 feet deep in the earth)
has attained somewhere about 56° F. This takes place about a week later than in
the air. Taking this into consideration, and that death occurs in a week to a fortnight
usually after the onset of the disease, it will be observed that the relationship
of the commencement of incidence of Summer Diarrhoea with the temperature
recorded at a point 4 feet below the surface of the earth, is corroborated to a certain
extent by the table given below, although it is not the opinion now that this is due
to the growth of a micro-organism in the soil, as described by Ballard.
There is no doubt that infection is largely spread through milk. Infants artificially
fed are much more exposed to infection than breast-fed infants, and breast
feeding renders children less s.usceptible to attack when exposed to infection, as well
as less likely to die when they are infected. This may account for the fact that there
are fewer number of deaths from Diarrhoea in the Whitechapel district than in
other parts of the Borough. It is well known that Jewish mothers suckle the children
more than others. In the Limehouse district, on the other hand, where a large proportion
of married women work in neighbouring factories, and consequently are
obliged to bring up their babies on artificial food, the mortality from Diarrhoea is
A good deal of attention has been paid within the last two or three years to
the possibility of conveyance of infection by the common house-fly. Many observers
maintain that flies are a great factor in causing Summer Diarrhoea, and in support
of their argument state that : (1) house-flies are present in immense numbers in
houses prior to primary attacks in those of infants, although not in all; (2) houseflies
have been shown by means of bacteriological examination to convey infection.
The matter was considered in detail by the London County Council in 1907,
and reported on by Dr. Hamer in 1908. Dr. Hamer came to the conclusion that
flies could not be the sole agents for the conveyance of Summer Diarrhoea from
patient to patient, because flies were found in houses in the late autumn after the
epidemic had ceased. It must be remembered, however, that, with the onset of cold
weather, flies become much more sluggish in their movements and would therefore
be less likely to spread infection rapidly.
In years gone by, before the advent of the motor vehicle, the number of flies
depended on increased mean temperature and diminished rainfall. With a record
dry and warm summer the flies in this district at any rate have not been so numerous
and have not been such a pest as in former years, although there has been a great