London's Pulse: Medical Officer of Health reports 1848-1972

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City of London 1919

[Report of the Medical Officer of Health for Port of London]

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In London both the Clayton apparatus and sulphur candles are used. The Clayton
apparatus cannot be in six places at once; and has of late been '' snowed under in the
utilisation of the new powers. 1 lb. in 1,000 cubic feet as a minimum burned in candle form
is found effective; the custom is to burn more.
Two replies mention that sulphur in larger quantities burns incompletely and only slowly.
I would suggest that, with a diffuse distribution of the candles or pots over the decks of
a large hold, any atmosphere which prevents rapid burning is lethal to rats; and on the other
hand, that if the candles or pots be massed, an atmosphere approaching that of a flame
extinguishing gas (11 per cent.) can be locally produced in low-lying regions, owing to the
sinking en masse of the concentrated S02 before diffusion takes place. Massing of candles,
especially in the deeper parts of the ship, is therefore to be avoided as delaying rapid diffusion
and tending to delay complete and rapid burning. The following data are useful:—
1 lb. sulphur gives 11.8 cubic feet of gas.
1 lb. sulphur gives 1.18 per cent, atmosphere of sulphur dioxide in 1,000 cubic feet.
per cent, atmosphere kills a rat with great rapidity.
Water absorbs 50 volumes of SO2
Considerable condensation and absorption takes place on and into all surfaces.
On fumigation, bilges should be dry.
I have ventured to interpolate a few remarks because in many cases our colleagues have
avowed a want of practical experience, or have asked for a definite lead in the matters which
are before us. The practical hints given by the larger ports in answer to question suggested to
me the expansion of these hints accordingly.
The following indications for disinfestation or methods of inspection are mentioned :—
Rats found dead on open hatches.
Evidence of rat depredations in food stores.
Observations of the crew and the amount of " droppings " left about.
That the vessel has come from an infected port.
That no recent disinfestation has been done.
The presence of rats as decided by enquiries.
Enquiries from Master.
Inspection of rat excrement.
All grain ships.
All ships from infected ports.
Evidence of Master and crew.
Store rooms, galleys and baker's shops should guide the inspection.
Enquiries of crew.
Inspection of bilges, limbers and ceilings of holds, fore and aft peaks, store rooms,
lazarettes, &c.
Presence of rats, especially dead rats, injury to foodstuffs, and lastly the following
complete Plague programme:—
(a) The fact that a vessel trades with a Plague infected port and is rat infested.
(b) The history of the vessel, Plague rats discovered at sea, an examination of the
ship's records.
(c) Examination by Medical Officer when boarding, statements by Master might
reveal indications of Plague infested rats or unusual sickness.
(d) Presence of rat Plague or unusual mortality.
9. Methods of inspection :—
Specially trained rat searchers and catchers duly appointed for the purpose will examine
for indications of rats.
The course pursued in London at present is that
(1) Every ship found on inspection or enquiry to be ratty,
(2) Every ship trading to the East which has not within six months been satisfactorily
disinfested by fumigations.
is fumigated immediately on discharge of cargo and in every part simultaneously. Qualified
inspectors decide as to rattiness and rat mortalities and enquiries are made of the personnel.
10. There is entire agreement on the desirability of intercommunication between Medical
Officers. The case has been succinctly put as follows:—The most convenient time (for fumiga"
tion) .will be when the holds are empty, and therefore vessels carrying part cargo may require
" reference from one Port Medical Officer to another. It would be a great advantage if definite
" arrangements were made on these matters between Port Medical Officers; already this is
" undertaken voluntarily to a large extent."
I have endeavoured to make the extraction of the answers sent as complete as possible; a
matter of ease since the unanimity of expression has been very large.
It has been found difficult to insist that every ship trading with the East, which
has not within six months been satisfactorily disinfested by fumigation, shall be
fumigated on discharge of cargo in the Port, It has been, however,"found advisable
that closer enquiry and inspection should be made by your Sanitary Inspectors, and
action taken according to the state of the ship as regards rattiness.

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