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NOTES ON AN OUTBREAK OF FOOD POISONING CAUSED BY
B. DYSENTERIC (SONNE).
By J. R. Tree, M.D., Assistant Medical Officer, Highgate Hospital,
and
J. M. Alston, M.B., M.R.C.P.E., Pathologist, Archway Group Laboratory.
In the civilian populations of the countries which have the best sanitary conditions,
the transmission of bacillary dysentery is usually by a series of infections
in which the excreta of any one patient infect only a small number of people, and for
this reason the course of an epidemic can often be traced from individual to individual
or from an individual to a group, with intervals between the successive infections
corresponding to incubation periods. But if an infected person (whether a sufferer
or carrier) prepares or handles the food of others, he may by contaminating it be
the cause of a much more wide and rapid spread of dysentery infection. Outbreaks
of this latter kind may be spoken of as food poisoning, and they resemble, epidemiologically
and clinically, those which are caused by certain bacilli of the genus
Salmonella, to which on account of the relative frequency with which they give
rise to such epidemics the name of food-poisoning bacilli is applied.
An instance of the way in which a dysentery infection may take on the character
of a food-poisoning outbreak is provided by an epidemic due to B. dysenierice (Shiga)
in a French village.4 The first case was that of a soldier who had been infected at a
military camp in a neighbouring county, and for the first week after he returned
home the infection spread only to relatives who attended him, and to the members
of a family which shared a privy with them. This was the family of the only baker
in the village and, a few days after it became infected, cases occurred rapidly in
all parts of the village and in the surrounding district. Thirty-one cases were traced,
with six deaths, in a population of 600.
An indication of the relative frequency of dysentery bacilli in food poisoning,
in Great Britain, is given by the fact that only 4 out of 100 outbreaks were definitely
traced to these organisms by Savage and Bruce White5. The bacillus was the Sonne
type in three instances, and the Flexner type in one. The number of cases identified
in these four outbreaks was 46 in all, and five deaths occurred.
Large epidemics due to transmission of dysentery infection by food are recorded
from time to time. In 1919, 150 children in a Hamburg orphanage were infected
with B. dysenterice (Flexner) by milk, and five died3. In Aberdeen, over 1,000 cases,
with 72 deaths, were caused by milk infection with the Flexner type of bacillus2. It
was clearly shown that the epidemic began in the household of a dairy farmer to
which infection had probably been brought by a relative who had nursed dysentery
cases in Salonica. The infection of milk with the Sonne type of bacillus occurred
at a dairy farm near St. Andrew's, and 150 cases of dysentery were identified in
that town1. No deaths occurred in that outbreak. At San Quentin State Prison,
in California, 946 out of 4,246 inmates were attacked during the course of 16 days
with dysentery caused by the Flexner type of organism7. The source of infection
was considered to be a physician who, as a convict, was employed in cutting and
distributing bread !
This report is written to record and comment on some of the clinical and
bacteriological features of an outbreak of food poisoning due to the contamination
of pease-pudding with B. dysenierice (Sonne). The epidemiology of the occurrence
has been reported6, and will therefore be mentioned only briefly.
On Saturday evening, 7th October, 1933, 18 or 20 people bought pease-pudding
in quantities of five or six ounces at a shop in the borough of St. Pancras. Thirteen
cases are known of very acute illness, which commenced a few hours after the pudding
had been eaten. On the next day six of the patients were admitted to Highgate
hospital and one to University College hospital. B. dysenterice (Sonne) was isolated
from the suspected food and strong presumptive evidence was obtained that the
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