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139
The investigations made show that it was unlikely that
infection from an animal source took place on the retailer's,
Mr. A.'s, premises. It remains to consider the possibility of the
infection originating from Mr. A. and his staff. The B. enteritidis
Gaertner was isolated from the stools of Mr. A., his son, wife, and
the errand boy. No history of any suspicious illness was obtained
in these persons. Mr. A., who was the most intimately connected
with the gammons in the first instance, would appear to be a carrier
of the organism, not a common occurrence as far as is known.
A Positive (1/40) agglutination reaction (trace 1/80) was obtained
in this case. Mr. A. Junior, however, gave a negative agglutination
reaction (1/20), which is not unknown in a carrier. Mrs. A. and
the errand boy were not tested.
If Mr. A. was the original source of infection, it is only
reasonable to suppose that he had only recently become infected,
as he had been boiling hams on the same premises for the last
twelve years without any untoward results. It is known that
a carrier may only excrete the pathogenic organisms intermittently,
but even so it is inconceivable, if Mr. A. was a carrier of longstanding,
that no infection of his food took place earlier.
Mr. A. Junior and Mrs. A. might have been contact carriers,
but it is difficult to explain the errand boy who is not one of the
family ; possibly he was infected in the shop.
It is possible that Mr. A. was himself infected from one of
the gammons in question, assuming them to have been surface
infected when they arrived at his shop. Alternatively Mr. A. may
have recently become infected from an unknown source. It may
be that Mr. A. became infected from one or other source on
19th or 20th August, but owing to his good state of health,
having just returned from a holiday, and his practice of tasting
the hams which he had cooked for the last twelve years or more,
when he may have been receiving constant sub-infective doses
of the bacillus, he suffered no recognisable ill-effects.
It is suggested that at this time he was excreting the living
bacilli in the stools, and owing to a lapse of cleanliness he further
contaminated the gammon which was put on sale on the Saturday,
21st August ; the weather being favourable, rapid multiplication
of the organisms took place and the gammon became heavily
infected, and later other articles of food in the shop, leading to
the explosive outbreak.