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would be proceeding, for surveillance for the balance of the fourteen days period. A daily medical
muster of those remaining on board would be carried out, i.e., surveillance would be carried out on
board the ship of all persons, including the Asiatic crew, remaining on board.
On Monday morning. December 1st, a telephone message was received from the Central Public
Health Laboratory reporting the case to be negative to smallpox and a letter was sent immediately to
all Medical Officers of Health notified of the arrival of contacts in their areas, stating that as a result
of this report surveillance need not be continued.
Some interesting and important points emerge from the incident:—
1. The arrangements made with the Postmaster-General for the despatch by air of laboratory
specimens worked perfectly. It appears that there was no delay whatsoever in getting the postal
package to Marignan aerodrome and the package was followed most closely and without delay right
through to its destination at Colindale. This may be regarded as highly satisfactory and the Postal
Authorities, here and abroad, are to be congratulated.
2. While all four cases were, clinically, typical cases of chickenpox, the laboratory investigation
and the report thereon was such as to render it necessary in my opinion to act as if one at least of the
cases was possibly a case of smallpox. Some further investigation will be necessary to see whether it is
possible for the virologists to be a little more precise in their interpretation of the findings, otherwise
the use of the theoretically admirable system of sending material for diagnosis by air well in advance of
the arrival of the ship may give rise to some doubt as to its practical value and lead to awkward
consequences. It might indeed result in a situation where, by the number of doubtful findings, some
slackening in the close surveillance of persons reported to be contacts with smallpox, would develop.
Such a situation would be most unfortunate and it is hoped that a review of the procedure will avoid
this because the potential value of a pre-arrival laboratory report confirming or rejecting the ship
surgeon's clinical diagnosis is, in my opinion, of the highest importance not only in the protection of
the country against the introduction of smallpox but also in reducing the disturbance to passengers
and expense to shipping companies.
SECTION X—Observations on the occurrence of malaria in ships.
Twenty-seven cases of malaria were reported on seventeen vessels during the year under review.
All the cases occurred amongst members of the crews, fifteen cases being disposed of prior to the arrival
of the vessels in this Port.
SECTION XI—Measures taken against ships infected with or suspected for plague.
Plague being primarily a disease of rats all vessels are inspected immediately on arrival at their
berths in the dock and river for the presence of any mortality among the rats on board which is not
attributable to any known cause, such as trapping, poisoning, etc.
Any such rats are immediately sent to the Central Public Health Laboratory at Colindale for
examination for bacillus pestis, each rat being accompanied by a label on which is given precise
information as to where the rat was found in order to arrive at a focus of infection should the examination
prove positive.
In the event of a positive result the discharge of the cargo would be promptly stopped and,
if necessary, arrangements made for the vessel to be fumigated throughout with hydrogen cyanide,
with the cargo in situ, the vessel being removed to an approved mooring.
Following the initial fumigation and collection of dead rats, further samples of which would be
submitted for examination, the discharge of the cargo would be permitted under observation. The
destination of the cargo would be ascertained and a note of the circumstances would be forwarded to
the Medical Officer of Health of the district to which the cargo was proceeding.
Should any of the cargo be discharged overside into lighters, such lighters would be fumigated
immediately they were empty.
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.
(1) Procedure for inspection of ships for rats.
The Port Health Authority employs thirteen Rodent Operators working in conjunction with and
under the supervision of the Sanitary Inspectors.
The Rodent Operators' first duty is the examination of such ships in his area as are due for
inspection under Article 19 of the Public Health (Ships) Regulations, 1952, relating to the granting of
Deratting and Deratting Exemption Certificates.
His second duty is to visit all ships arriving in his district, to search for evidence of rats, paying
particular attention to vessels which have arrived from plague infected ports and to visit such vessels
during the discharge of cargo.
The Rodent Operators' third duty is the examination of shore premises for signs of rat infestation
paying particular attention to premises adjoining the berths of vessels from plague infected ports.
In 1941 the Port Health Authority instituted a Rodent Control Scheme in all docks and premises
of the Port of London Authority, on behalf of that Authority and in the premises of the tenants of the
Authority on behalf of the occupiers.
This scheme in its early days, relied principally on trapping but with experience and the application
of a more up-to-date knowledge of the habits of rats, new and scientific methods of poisoning
gradually took the place of trapping, the latter now only being occasionally used to clear up residual
rats, if any, which have escaped a major poison operation.
The Port of London Authority have made byelaws requiring the Master of every ship to cause all
ropes and mooring tackle to be fitted with guards to prevent rats passing from ship to shore. The
byelaws also prescribe that when the discharge or loading of cargo is not actually proceeding, one
gangway, whitened for a length of 10 feet at the end next the vessel, may be used as communication
between the ship and the shore.
(2) Arrangements for the bacteriological examination of rodents, with special reference to rodent
plague, including the number of rodents sent for examination during the year.
As described in Section XI above all rats for examination for plague, either by post mortem and
subsequently, if necessary, by bacteriological examination, are promptly sent to the Central Public
Health Laboratory at Colindale.
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