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Londen County Council.
FLIES AND VERMIN.
Report by the Medical Officer of Health presenting reports by Dr. Hamer, Medical
Officer (General Purposes), on Nuisance from Flies and on the Seasonal
prevalence of Vermin in Common Lodging Houses.
(Ordered by the Council to be printed, March 1st, 1910.)
During the summer of 1909 investigations with regard to "Nuisance from Flies," on lines
similar to those followed in 1907 and 1908, have again been made. In addition, however, to
counting the flies caught at the various places of observation, the species have been, as far as practicable,
determined, and charts showing the seasonal distribution of these species have been prepared.
Two methods of capturing the flies have been employed, first by means of sticky papers and, second,
by "balloons"; the results obtained will be found to present certain marked points of contrast.
This fact suggests that caution is necessary in comparing the work of observers employing differing
methods in different localities. In the light of the three years' records now available, a further
examination of the "fly hypothesis" of causation of diarrhoea and typhoid fever can be made. The
view expressed in previous reports, that a critical attitude, as regards acceptance of this hypothesis,
should be maintained, must be still adhered to.
During the year 1909 observations were made with regard to the prevalence of fleas, bugs and
lice in beds and bedding in common lodging-houses. By plotting out the figures, curves showing
the seasonal distribution of these three kinds of vermin have been obtained and are exhibited in
Diagram IV.
Supervision of common lodging-houses probably gives better facilities than can be found in
any other branch of work for this purpose, for, notwithstanding the fact that the Council's inspectors
are continually employed in the examination of houses and beds for evidence of the existence of vermin
with a view to their destruction and prevention, there is abundant opportunity for the daily
reinfection of beds by those who are habitually infested with these pests.
The fact, however, that there is a constant conflict between the two opposing forces—the
action of the inspectors and of the keepers of the houses on the one hand, and the continued reintroduction
of vermin into the houses on the other—renders the result, so far as it indicates a natural
phenomenon, somewhat uncertain. Dr. Hamer's report shows the difficulties which were met with
in the inquiry and the steps which were taken to surmount these difficulties, but it should be
remembered that the observations of a single year must not be accepted too unhesitatingly as
showing with any exactitude the seasonal prevalence of vermin, even if the method of inquiry adopted,
the only one which seemed possible, provides a sufficiently reliable basis for inference. These results
are, however, deserving of being put on record if for no other purpose than that of encouraging others
who have opportunities to make similar inquiry.
In reading Dr. Hamer's report it needs to be borne in mind that the percentages of infested
beds have been obtained by precise and detailed examination of each bed selected as a statistical
unit. This examination has been made by highly skilled observers, and the slightest evidence of the
presence of vermin, nits, stains, etc., has been regarded as sufficient reason for inclusion of the bed
in the infested class. Dr. Hamer's report (page 8) also shows the efforts which have been made to
secure the same severe standard by each observer so as to obtain as far as possible uniformity of
method.
Observations concerning the rat-flea and plague and the bug and relapsing fever, suggest
possibilities with respect to the common infectious diseases, and point to the need for extension of
knowledge concerning the natural history of human parasites in this country. An early step in
this direction is to learn their seasonal prevalence, and Dr. Hamer endeavours to supply on this
point such information as it has been practicable to obtain by inquiry during one year in London
common lodging-houses.
546
Shirley F. Murphy,
Medical Officer of Health.
A