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Nevertheless the matter must be viewed objectively and in the light of a number of factors such
as the incidence of plague infected rats found in the Port over a number of years, the cost of the
service, the probability that the routine practice will have a bearing on the protection of the Port
against plague and finally in the event of a plague rat arriving in the Port the probability of the
transmission of the disease to the rat population in Port installations.
To take each of these features seriatim, a plague infected rat has not been discovered in this Port
since 1927, consequently the Laboratory examination of rats has been continued year after year for
some 25 years, without any positive result.
The incidence of rats in ships which increased considerably under war conditions has now returned
to a pre-war state and is indeed much less than the incidence in pre-war days. This is confirmed by the
diminishing number of rats destroyed in ships and the proportionately small number of deratting
certificates issued as compared to exemption from deratting certificates.
The rat population in the Port is now so small and is under such strict control that it can be said
to be almost certain that the arrival of a plague infected rat would be highly unlikely to have any
serious significance. In other words, an epizootic could not be introduced into the Port for the simple
reason that there are insufficient rats to support an epizootic of this kind.
Consequently the routine examination of rats was abandoned early in 1952 and only rats
found dead in circumstances which might possibly indicate the presence of plague are being sent to
the Laboratory. During the year 9 rats were sent to the Central Government Laboratory, none being
found to be infected with plague.
(3) Arrangements in the district for deratting ships, the methods used, and, if done by a commercial
contractor, the name of the contractor.
(а) The burning of sulphur at the rate of 3 lbs. per 1,000 cubic feet of space for a period of not
less than six hours.
The destruction of rats, whether it be by the open pot method or by sulphur gas is efficient and
the great advantage is that when applied in the holds of a ship the crew need not be put ashore.
Unfortunately a number of countries have, for some time past, refused to accept as valid, International
Certificates, where this method of rat destruction has been employed; consequently it has
fallen out of use.
(b) The generation of hydrocyanic acid gas by various methods. Por the destruction of rats a
concentration of HCN at the rate of 2 ozs. per 1,000 cubic feet of space is required with a minimum of
two hours contact. If the fumigation is for the destruction of insect life, bed bugs, cockroaches, etc.,
two or three times the concentration is employed and the exposure increased up to twelve or even
twenty-four hours, according to the time available.
(c) "1080" and "Warfarin." The employment of the new rodenticides "10800" and "Warfarin"
are referred to elsewhere in this report.
The employment of "1080" has been used regularly throughout the docks with highly satisfactory
results. There is every indication that its use in ships is equally satisfactory to its use ashore.
A certain number of ships have been deratted by this method in preference to the use of cyanide,
resulting in a considerable saving in time and cost to the shipowner.
Satisfactory results have been obtained from the use of "Warfarin" but a suitable bait, particularly
in granaries, with which to mix the poison which rats will take continuously in preference to the
grain or other form of cereal on which they are normally feeding, has yet to be found.
(d) Trapping. Trapping is seldom employed save for the destruction of isolated rats which have
not yet established themselves.
The following are the names of the firms approved for carrying out the deratting of ships:—
Messrs. Associated Fumigators, Ltd. Messrs. Fumigation Services, Ltd.
Messrs. London Fumigation Co., Ltd. Messrs. Ridpests, Ltd.
Messrs. Deodor-X Hygiene Services, Ltd. Messrs. Insecta Laboratories, Ltd.
RODENT CONTROL.
The use of Sodium Fluoroacetate ("1080") as a rodent poison has been continued during the
year both in dock installations and in ships and is now well beyond the experimental stage.
Thanks to its use in the warehouses, offices and other premises in the docks it can safely be said
that it is now difficult to find, even in grain silos and other highly rat attractive premises, any rodent
infestation of appreciable dimensions and the comparatively small number of rats that are reported
following control measures are for the most part due to incursions from surrounding areas.
As regards ships we have maintained the thesis that in a majority of ship infestations the use of
" 1080 " is as good and effective as hydrogen cyanide and at a quarter of the cost to the shipowner.
An interesting example may be quoted—
A foreign going ship lying in the West India Dock was, on inspection, found to have a
well marked infestation of rats in Nos. 3 and 4 holds and was, in any ease, due for cyanide treatment
against a weevil infestation (she was engaged in the grain trade with Canada). On an experimental
basis, therefore, agreement was reached with the Agents to permit a "1080" operation following
which the two infested holds would be thoroughly searched for dead rats and the following evening
a cyanide fumigation would be carried out and again a thorough search would be made for dead bodies.
Following the "1080" operation 68 bodies were recovered. The holds were then fumigated
with hydrogen cyanide and no bodies at all were recovered. It must be accepted that this is pretty
conclusive evidence of the efficiency of " 1080."
Despite evidence of this kind and not inconsiderable endeavour to persuade other ports to adopt
the use of "1080" for the deratting of ships, coupled with the not unnatural interest of the industry
in a method which not only costs them very much less than a cyanide fumigation but renders to
putting of the crew ashore during the operation unnecessary (in itself a very considerable saving in
cost) it must be regretted that this method has not caught on and is not used, at least to any appreciable
extent, in other ports.
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