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"Lord Fleck, a former Chairman of I.C.I. Ltd., has written of how 'the Macedonian Phalanx
and the Roman legion, the bowmen of England and Cromwell's Ironsides, each formed a decisive
contribution to the technology of warfare, but in the American Civil War (during the first
industrial revolution, in the mid-nineteenth century) for the first time, the technological resources
of a whole nation were ultimately mobilized to overwhelm an opponent. There was mass-production
of weapons and ammunition, of uniforms and boots; canned food was supplied to armies transported
for the first time by rail. In a famous dispatch to Lincoln in 1862, John Ericsson, who had designed
the floating armoured battery Monitor, wrote: "The time has come Mr. President, when our
cause will have to be sustained not by numbers, but by superior weapons. By a proper application
of mechanical devices alone will you be able with absolute certainty to destroy the enemies of
the Union." ' "
These mechanical devices undoubtedly included canned foods.
I do not propose to describe the fabrication of the sanitary can as described in a standard
text book19 or more recently at the Conference on the Safety of Canned Foods20. Hitherto reliance
has been placed on subsequent storage for a few weeks in order that spoilage may be observed by
physical examination of the cans for evidence of blown cans. Now we are led to believe that
microleakage can admit living pathogenic organisms that are not revealed either during the period
of initial storage nor indeed at any time by mere inspection of the can. Typhoid organisms apparently
can gain access and multiply to such a degree as to be the initial cause of an outbreak such
as has occurred in Aberdeen without any obvious change in the contents when the can is opened.
We are informed that there can be either a selective entry of typhoid organisms or more likely a
predominant growth of typhoid germs after entry with suppression of an adequate growth of gasproducing
organisms to give evidence of their presence by blown cans.
It should be noted that the three 1963 outbreaks at Harlow, South Shields and Bedford were
associated with one particular brand of corned beef produced at Establishment Argentina No. 25
at which untreated river water was used for cooling cans of corned beef after sterilization. The
number of the cans associated with the outbreaks in the United Kingdom indicated that meat
canned at the factory on and after the 30 May 1962, were suspect and these were voluntarily
withdrawn by the distributors. Stocks of corned beef from the factory were examined over a period
of time, and some on bacteriological examination yielded pure cultures of faecal coli. Furthermore,
the spoilage of the products of this particular factory were four times the normal21. It was
definitely established that the outbreak at Harlow in 1963 was associated with canned corned beef
and it was very probable that the corned beef was contaminated during manufacture, either by
cooling in polluted water which had access to the can or by a typhoid carrier handling the can
while still wet after cooling.
The development of modern food supermarkets, where large numbers of persons are served
are more likely to cause large outbreaks than small stores or butchers' shops. There is the added
special risk from meat whilst on display at the counter. The diversity and quantity of meats served
and handled means that the contamination can spread widely through a diversity of products by
the use of slicing machines or knives for cutting. The habit of storing unsold portions in a refrigerator
during the night means that various products are cross-infected. They are then all redistributed
the next day on display counters to incubate at room or warm window temperatures,
unless special refrigerated display counters are provided. There is also the danger of various
employees handling the different kinds of meat, and some of them even becoming symptomless
carriers.
Some local authorities have compulsory registration of butchers' or fleshers' shops at which
fresh meat only was traditionally sold, but during the war years, the necessity of selling other
forms of meat, such as tinned corned beef, led to the introduction of the sale of these kinds of
meat and many other articles of food from butchers' shops. This, together with the development
of large stores and supermarkets has increased the risks as outlined above.
P. M. Meers and D. Goode22 at the Royal Army Medical College have done experiments on
intact cans of corned beef actually inoculated with Salm. typhi as the sole contaminant. The cans
were resealed, stored and contents examined for Sal. typhi at various intervals. The Salm. typhi
spread rapidly throughout the corned beef at 37°C. and much more slowly at room temperature.
Escherichia coli, although a gas-producing organism, alone or in combination with Salm. typhi
did not "blow" cans, though cans with C. Welchii and E. coli did blow. It is probable that if
any batch of cans exposed to faecal contamination and containing typhoid organisms some will
be infected with C. Welchii as well as Salm. typhi and so act as indicator. Meers and Goode
suggest that blowing of tins might be used as an index of potentially dangerous contamination.
It is not enough merely to reject blown cans in these circumstances. A percentage of blown
cans above a certain level should lead to rejection of the whole batch. In the circumstances of
the Aberdeen outbreak, the presence of four times the usual number of blown cans should have led
to rejection of the whole batch in addition to the fact that untreated water was used for cooling.
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