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Report of the Medical Officer of Health
107
In West Ham there were two areas affected; in one there were some 50 cases, in the other 13.
These outbreaks were believed to be due to cockles. (See Annual Report, Medical Officer, West Ham,
1906.) At the time there were felt to be difficulties with regard to the cockle hypothesis, for in West
Ham, and this was the case in London also, only about half the sufferers gave a history of eating cockles.
The London patients were all personally questioned by me with regard to this matter, and with
reference also to fried fish. The argument was, however, used that 50 per cent. of cockle eaters is a
larger percentage than obtains in a random sample of the population. If 50 per cent. admit
having eaten cockles, it was urged, may not more have actually done so ? At the time this difficulty
was not completely eliminated.
Attack of seven persons in one family in Chelsea in May, 1907.—My attention was called to these
cases by Dr. Parkes. These seven persons (five living in one house and two in another house) developed
typhoid fever between 13th and 17th May. I made careful enquiry as to the food consumed by the
seven sufferers. The two persons who lived away from the other five had some meals in common with
them. The only food supply, among foods believed capable of transmitting the infection of typhoid
fever, common to all seven persons, was found to be fried fish.
The prevalence of 1908.—In 1908 an outbreak of typhoid fever occurred in Bethnal Green, which
was studied in detail (Appendix I., Annual Report of the Medical Officer of Health of the County of
London). In this outbreak, as in that of 1906, the question was narrowed down to one between fish
and shellfish, the shellfish under suspicion being, however, now mussels not cockles. As in 1906,
it was found that a fried fish hypothesis was adequate to explain the outbreak, for, making allowance
for sporadic cases, all the sufferers were fried fish eaters. As regards mussels, out of 28 cases, only nine
or ten patients gave a positive history—clearly, therefore, a mussel hypothesis was inadequate as a
sole and sufficient explanation of the prevalence. There remained, however, the fact that the percentage
of mussel eaters was considerable. Enquiry in a "control population" led to the conclusion
that out of 28 sufferers, only five or six could be expected to be mussel eaters, and here among the 28
sufferers were nine or ten mussel eaters. This explanation, however, is really sufficiently obvious. The
control population may be divided into two portions, a fried-fish-eating portion and a non-fried-fisheating
portion. Clearly the habits of these two portions may differ as regards eating mussels and other
shellfish. It might, perhaps, be anticipated that among the fried fish eaters there would be a higher
proportion of shellfish eaters than among the non-fried-fish-eaters. Assuming, for the purpose of
argument, that typhoid fever picked out in the prevalences of 1906 and 1908 the fried fish eaters,
it might so chance that the outbreak was selecting a population containing in 1906 a somewhat higher
percentage of cockle eaters, and again, in 1908 a somewhat higher percentage of mussel eaters than the
control population. As a matter of fact, almost half the sufferers in 1906 had eaten cockles (the
outbreak occurred in the cockle season), and nearly half the sufferers in 1908 and again in 1910
(outbreaks occurring in the mussel season) had eaten mussels. The percentages, of cockle eaters
among the sufferers in 1906, and of mussel eaters in 1908 and 1910, were higher than those of
control populations, because the suffering population was a selected population; the typhoid fever
had, in fact, in selecting fried fish eaters, chosen populations having comparatively high percentages
of shellfish eaters. The explanation is thus the obvious one—that the fried fish eater is more fond of
shellfish than the non-fried-fish-eater. The possibility may be mentioned that the fried fish eater is
more partial also to other articles, such as watercress and ice cream, (i.)
The prevalence occurring early in 1910.—One other prevalence must be referred to. Dr. Parkes,
Medical Officer of Health of Chelsea, on 12th February, called the Council's Medical Officer's attention
to three cases of typhoid fever. Dr. Parkes wrote: "I am inclined to think that these cases are due to
something the boys buy in the streets.'' Enquiry yielded no feature common to the three cases save
consumption of fried fish. Coincidently with these cases there occurred six cases in Wandsworth. I
conferred with Dr. Caldwell Smith with regard to these cases, and the result of our joint enquiries led
me to suspect that they had the same origin as the Chelsea cases. One of the Wandsworth cases was
that of a girl living in an institution in Wandsworth. A girl living in Fulham was a day scholar at this
institution. The two girls developed typhoid fever at about the same time. The only meal partaken
of in common by the two girls was dinner, and all the articles of food (other than fish) which have been
credited with transmitting typhoid fever could be absolutely excluded. Six cases (five from one
house) in Stepney occurred coincidently with the above cases. Here again, suspicion fell upon fish,
and curiously enough fish from a source which again came under suspicion in 1910. Moreover, 15 cases
occurred in members of three families living in the same neighbourhood in Camberwell, at about the
same time. The facts regarding this group of cases admit of more than one interpretation; but in
view of the time relations of this group and the other groups it is probable that they were also fish
cases. These prevalances illustrate the difficulties associated with the question of infection by fish;
at the same time they point to the probability that fish infection is a not uncommon cause of occurrence
of sporadic cases of typhoid fever in London.
As to the Contamination of the Fish.
There is a question with regard to the way in which fish become capable of transmitting infection
which must now be briefly referred to. In the case of the outbreaks of fish typhoid of 1900 two points
were already clear,
(i) In this connection attention may be called to two outbreaks of typhoid fever in Hackney in 1903, and to a
third prevalence there in 1904. The outbreaks had been attributed to watercress, but facts which have since come
to light throw some suspicion upon fried fish.
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