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considered. An even greater degree of suspicion must rest upon outbreaks ascribed to ice-cream, water
cress, etc.; at least this may be confidently urged with regard to a particular prevalence, that of 1911,
in Finsbury, which was at first ascribed to ice-cream, but this judgment was later (Ann. Rep. of Council,
1911, Vol. III., p. 83) found to need reconsideration.
The first suspicions concerning fish and shellfish in relation to infectious disease were entertained
at the time of the cholera outbreak of 1892-93. Sir R. Thorne ascribed some of the cases occurring in
this country to shellfish from Cleethorpes, near Grimsby. Only some half dozen cases of cholera were
detected in London (Ann. Rep., 1893, and Appendix to Rep. of 1900, p. 7), and in three of these the only
article of food which could be incriminated was fish from Grimsby. In the next two or three years
question was raised as to conveyance of typhoid fever by oysters, and later by mussels and other shellfish;
in 1900, came the first clear evidence of conveyance of typhoid by infected fish (Ann. Rep., 1900,
Appendix I.).
The behaviour of typhoid fever in London in successive periods before and after 1870.
On a broad review a division into five successive periods of time, each representing a downward
step in prevalence, may appropriately be made. (See Diagram, p. 11.)
(i.) The period prior to 1870. Typhoid much confused with typhus, but maintaining,
undoubtedly, a high level of prevalence, and perhaps showing gradual decline towards the end
of the period. During the years here under review outbreaks were commonly attributed to
insanitary conditions generally, particularly to cesspools, privies, etc., and quite towards the
end of the period, occasionally to water and milk.
(ii.) The period 1870-1884. Typhus now falling rapidly: typhoid still at a relatively
high level of prevalence though probably rather lower than heretofore; if anything it gradually
declined throughout this period. Outbreaks were usually ascribed to "drains," or to water,
milk, or sub-soil pollution ("ground water" hypothesis of the Munich school).
(iii.) The period 1885-1900. Typhoid now on a still lower level of prevalence, but not
showing further diminution during the period itself. Water and milk still commonly assigned
as the cause of outbreaks ; considerable attention now being directed, however, to certain new
hypotheses such as that of spread by flies, and case to case infection was also now much canvassed;
no very conclusive evidence was forthcoming supporting the view that the two last
named are important factors in spread of the disease; the "ground water" hypothesis steadily
gave way, however, throughout this period as more and more emphasis was laid upon the
new hypotheses deduced from consideration of possible influences exerted by the recently
discovered typhoid bacillus. Shellfish and fish towards the end of the period were first clearly
shown to be causes of typhoid outbreaks.
(iv.) The period 1901-1914. Typhoid still declining; this period marks the fourth downward
step. The decline within the period itself is at first rather marked. Throughout the
fourteen years much attention was devoted to the question of infected food supplies, particularly
shellfish from polluted foreshores. Outbreaks were still ascribed from time to time to water
and milk. A new hypothesis, that of the spread of disease by healthy carriers was now much
discussed, but little, if any, unquestionable evidence of its operation was discoverable in
London.
(v.) The war period and immediately after. Typhoid still shows a disposition to decline.
The fall is ascribed by some to diminished consumption of food materials from polluted sources ;
by others to further improvement in water supplies and the increased attention paid to sanitary
conditions generally; while a third school of opinion, the ultra-contagionist, finds explanation
of the decline in the sporadic and often ineffectual attempts made to control healthy carriers,
aided by the partial operation upon certain sections of the population of protective inoculation.
Study of the Diagram, which exhibits the time relations of the dates of inauguration of successive
attempts to control typhoid fever, and those of variation in the rate of decline of the disease, will make it
clear that the marked fall which has occurred in the last 40 years cannot be the outcome of the healthy
carrier campaign carried out for some 10 or 12 years (1903 and onwards) in South-west Germany, and
practised, still more recently and for much shorter periods of time, in a patchy and uncertain manner
in a small number of instances, in the United States and in this country. The influence of improved
methods of inoculation, moreover, has only been exercised on any considerable scale during the last five
or six years, and has been in the main limited to military populations; moreover, the men in question
have had their water supplies carefully safeguarded (see the reference to chlorine sterilisation processes
in Sir A. Houston's historical summary in Reports of the Progress of Applied Chemistry, Vol. IV., 1919).
The recent report of Major Vaughan, on typhoid in inoculated American soldiers, goes to show that
no lessened severity of attack occurs in the inoculated ; while the assumption that some degree of protection
against attack is afforded, is based on comparison with results obtained in the Spanish-American
war of 1898; this comparison is beside the mark, typhoid fever having lost a large part of its terrors
in the intervening 20 years. (JI. of the American Med. Assoc., 24th April, 1920.) Friedberger's recent
report (" Zeit. fur Immunitats." Jena, 1919) is to the effect that the case for inoculation is not proven,
if judged by the German Army Statistics.
Causation of typhoid fever by consumption of sewage-polluted shellfish.
It seems clear, moreover, that among the factors operating in producing the great fall in typhoid
prevalence of the last 20 years, the amelioration of conditions obtaining in connection with the harvesting
of fish and shellfish from inshore waters must have played a not inconsiderable part. It is proposed now to
indicate, as far as may be, the extent to which this factor has come into play. As regards shellfish, in
America and in this country, and in less degree elsewhere, careful enquiries have been made for 20 years
ast with regard to the risk of consuming oysters, clams, cockles, mussels, etc., from polluted sources. Dr.
P