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Sixty five rats were sent to the Laboratory during the year and were examined for plague, all
results were negative.
Arrangements in the district for deratting ships, the method used, and if done by a commercial
contractor, the name of the contractor.
Arrangements exist in all areas for the deratting of ships by private contractors, under the
supervision of the Port Health Inspectors, using the following methods:—
(a) 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.
(b) The generation of hydrocyanic acid gas by various methods. For 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.
Both the above methods are very seldom used nowadays and in fact were not used at all
during 1965, owing to the cost of the operation and the time taken overall.
(c) '1080', and 'Warfarin'. Sodium Fluoroacetate (1080) is now used for the deratting of ships
in London more than any other method owing to its ease of operation and the saving of
time and cost to the shipowner.
(d) Trapping. This method is seldom used except for the destruction of isolated rats which
have escaped a major poisoning operation or which have not yet established themselves.
(e) Methyl Bromide. This is an effective and lethal fumigant with considerable penetrating
powers and is not difficult to disperse after an operation. It is also used as an insecticide,
particularly in the dry fruit industry and therefore where there is an infestation of
rodents and insects the combined problem can be solved with one operation.
The following firms are approved for carrying out the deratting of ships:—
London Fumigation Co. Ltd.
Rentokil Laboratories Ltd.
Contra-Pest Service Ltd.
Progress in the Rat-proofing of ships
Particular attention has been directed towards rodent-proofing both afloat and ashore. The
purpose is to deny rodents harbourage in which to hide and breed, to restrict channels of communication
and to deny access to food and drink. The principles are a profitable investment and
have accounted for a substantial reduction in persistent rodent infestations, while facilitating the
intermittent extermination measures when required. It is encouraging to notice the steady decline
in the number of ships in need of deratting measures and this improvement is attributed to better
international control, more sanitary construction and reflections of health education. The same
principles have been adopted in the construction of new premises in the Docks in which respect
the cooperation of the Port of London Authority is always fully received.

The number of rats recovered represents a numerical decline which has been a feature for
some years past, but is in no way related to any relaxation of effort. The reduction could be
attributed to rodent-proofing and it could be influenced by the modified range of rodenticides.
The number of dead rodents actually recovered can be assumed to be a proportion of those actually
exterminated, although most rodents poisoned by '1080' are incapable of straying after the intake
of the poison and this has proved of immense value to the searcher for specimens.
The decline of infestations aboard sea-going ships also continues and the sustained control
on the harbour lighters has proved invaluable in restricting the spread of infestations around the
Port, in providing a reliable check on the health of the rats within the Port and, of considerable
importance, in reducing the number resident to breed, thereby causing substantial economic losses
to food and property.
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