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Following the initial fumigation and collection of dead rats resulting therefrom, further
samples of such rats would be submitted for examination and the discharge of cargo would be permitted
under observation. The destination of the cargo would be forwarded to the Medical Officer
of Health of the district to which it was proceeding, together with an explanatory note.
If any of the cargo had already been discharged overside into lighters before the discovery of
plague infection, the lighters would be fumigated immediately.
On completion of the discharge of cargo from the vessel a second fumigation would be carried
out, again using hydrogen cyanide, to destroy the residual rat population, if any.
SECTION XII
MEASURES AGAINST RODENTS IN SHIPS FROM FOREIGN PORTS
(i) Procedure for inspection of ships for rats
The Port Health Authority employs an experienced and competent team of fifteen Technical
Assistants, who exercise control measures on all ships and shore premises within the Port area
under the supervision of the Port Health Inspectors.
The Technical Assistant's first duty is to visit all ships arriving in his district as soon as
possible after arrival and search for evidence of rodents. Priority is given to ships which have
arrived from plague endemic areas. Further visits to these ships are made during the discharge
of cargo to ascertain the degree of infestation on board, if any, and to ensure that reasonable
measures are adopted to reduce the number of rodents on board to a negligible number and prevent
any rodents escaping ashore.
His second duty is the inspection of ships in his area for the specific purpose of issuing
Deratting or Deratting Exemption Certificates or Rodent Control Certificates.
Histhird duty is the inspection of shore premises and lighters for signs of rodent infestation.
The Port Health Authority has continued to operate a Rodent Control Scheme inaugurated
initially in July, 1941, covering all the docks and including all the premises of the Port of London
Authority on behalf of that Authority and premises of tenants of the Authority on behalf of the
occupiers.
(ii) Arrangements for the bacteriological or pathological examination of rodents with special reference
to rodent plague including the number of rodents sent for examination during the year.
All dead rats to be examined for evidence of plague are promptly dispatched in cylindrical
aluminium containers with a screw cap to the Public Health Laboratory at County Hall.
Specimen rats are placed in polythene bags previously dusted with gammaxene powder to kill
any parasites, labelled and placed inside the cylinder for delivery by hand. During the year
thirty-six rats were sent to the Laboratory at County Hall and were examined for plague with
negative results.
(iii) Arrangements in the district for deratting ships, the methods used and if done by a commercial
contractor, the name of the contractor.
(a) The burning of sulphur at the rate of 3 lbs per 1,000 cubic feet of space for a minimum
period of 6 hours. This method is seldom used now in the Port of London.
(b) The generation of hydrocyanic acid gas by various methods. For the destruction of rats
a minimum concentration of H.C.N. at the rate of 2 ozs per 1,000 cubic feet of space is
reauired with a minimum of two hours exposure.
(c) Sodium-fluoroacetate ("1080") and "Warfarin". The employment of "1080" as a rodenticide
has been regularly used throughout the docks for some time with highly satisfactory
results. The prohibition on the use of "1080" and "1081" (Sodium Fluoroacetamide)
except in ships and sewers, which was imposed in June, 1965, was amended during
1970 to permit their use also in enclosed dock premises. The deratting of ships by
"1080" in preference to the use of cyanide results in a considerable saving of time and
cost to the ship owner.
(d) Trapping. This method is seldom used except as an expedient to eliminate isolated rats
and/or to secure specimens for the laboratory.
(e) Methyl Bromide
Methyl Bromide is a gas at ordinary temperatures but can be liquefied by pressure, and
it is in the liquid form in the cylinders in which it is usually distributed.
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