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"Boroughs of Islington and Wandsworth, and which were attributed to the
"consumption of mussels, which on enquiry were found probably to have come
"from Holland, and Dr. Klein, to whom mussels alleged to have come from the
"same source were submitted, found evidence of what he regarded as fecal
"contamination. Consequently the Consul-General of the Netherlands was
"communicated with upon the matler.
"The type of enteric fever caused by shellfish is not improbably a severe one,
"with a high fatality rate and a short incubation period."
In dealing with the evidence available as to the connection between Enteric Fever
and Shellfish, the report states:—
"Such evidence must of necessity be circumstantial, since absolute proof in
"dealing with epidemiological problems, such as are here involved, is practically
"unattainable. Moreover, the evidence in this instance must be not only
"circumstantial but largely cumulative, that is to say made up of a succession of
"associated events repeated sufficiently often to bestow upon them a definite value
"qua evidence. It is, of course, of little importance to know that certain persons who
"develop enteric fever have consumed raw shellfish, since this fact in the present
"state of our knowledge merely implies that such persons have recently eaten
"something which is believed under certain circumstances to be capable of causing
"enteric fever or other gastric disturbances. But this fact alone has little, if any,
"more value that the bald statement that the patient had consumed water or milk,
"had inspired drain air, consumed raw vegetables, or lived in a house where the
"conservancy system of excrement disposal obtains, all of which articles or
"circumstances are to be thought of as being capable of inducing attacks of
"enteric fever.
"It is clearly essential to know, not only at what date or dates, shellfish had
"been eaten, but also to what other sources of infection, if any, the patient had
"been exposed.
"But not infrequently, the mere statement ' had eaten shellfish ' is considered
"sufficient for the inference that this was the cause of the illness, no other possible
"sources of infection having been looked for, or at least, discussed, albeit other
"cases of enteric fever are ascribed to other causes, such as those above referred to.
"But even if the shellfish could be shown to have come from a source liable
"to pollution, and to have been consumed raw, at a date consistent with its
"causation of enteric fever, the two events need by no means be causatively
"related, since for example, had the case in question been one of a group which
"had apparently been infected by milk, water, or foods other than shellfish,
"the cumulative evidence pointing to the latter agents would outweigh that in
"connection with a single event.
"It must not be forgotten, too, that the etiological value which is to be
"attached to the circumstances of an enteric fever patient having eaten shellfish
"within say three weeks of the onset of the disease, depends very largely upon the
"proportion of the population which habitually or even occasionally consumes
"shellfish.