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104
as the months of the lowest incidence of enteric fever ; so that at this
time sewage contains the minimum of specific material, i.e., the
organisms of enteric fever. Sewage may during this time, or until
the specific material has been reinforced by the seasonal increase of
enteric fever, pollute watercress without producing anything more
than slight intestinal disorder; but when the specific material is
increased to a certain quantity, then enteric fever may be produced.
This increase of material may begin as a result of the seasonal
increase of enteric fever, or at an earlier date due to such a
phenomenon as excessive rain which has washed into the watercourses
morbific matter, or diminished the purifying effect of sewage farms
and raised the disease-producing effect of their effluents, which are
used in many cases for the growth of watercress.
The harm-producing possibilities of sewage-grown watercress are
very far reaching, but I will not dwell upon them here. I will conclude
by repeating my conviction that the late outbreak of enteric
fever in the Borough of Hackney has been??? largely caused by
specifically infected watercress.
The conditions revealed to me by my enquiry convince me that (1).
An extended enquiry should be made as to the conditions under
which watercress supplied to the Metropolis is cultivated. (2). Representations
should be made by the Borough Council to the County
Borough of West Ham, pointing out the conditions under which
watercress is cultivated in that Borough; and asking them to take
such steps as may be needful to ensure in future that watercress
grown in that Borough shall be free from pollution.
My thanks are due to Dr. Shirley Murphy, Chief Medical Officer
to the London County Council, for kind criticism, and to Dr.
Goodall, Superintendent of Eastern Hospital, for making enquiries
amongst his patients.
I remain, Gentlemen,
Yours faithfully,
J. KING WARRY, M.D., M.R.C.P., &c.,
Medical Officer of Health.
Town Hall, Hackney,
November, 1903.