View report page

38
Of the six cases returned as both typhoid and paratyphoid in 1925, two were
paratyphoid B, two A and B, and two were paratyphoid not further defined. The
corresponding details for the five cases in 1924 were three paratyphoid B, one A and
B and one paratyphoid not further defined, and for the nine cases in 1923, two paratyphoid
A, four B, and three A and B.
Notes on the
epidemiology
of typhoid
fever.
The great decline in this disease observed during the last 25 years, has aroused
the keenest interest, and varied explanations have been given of the phenomenon.
From a purely bacteriological point of view, it may perchance be noted that there
is now available a new means of diagnosis (Widal reaction; isolation of the bacillus
from blood culture, etc.), and the point has even been stressed that this method has
been increasingly employed since about the time wen the decline of typhoid fever in
civilised communities became specially accentuated; again, it is said, preventive ininoculation
and control of bacillus carriers have been extensively practised during
recent years. From the epidemiological point of view, on the other hand, it is naturally
argued that 20 years prior to the time in question, steady effort was made, particularly
in this country and in Germany, to improve water supplies; and at least 10 years
before that same date, a strenuous campaign was inaugurated here to prevent
consumption of polluted shellfish. These two lines of action were, moreover, actively
followed, after intervals of (roughly speaking) some 10 years in other countries,
notably in the United States. It is a very striking fact that after corresponding
intervals (from the dates of commencement of gradual, and then of rapid decline,
here in England), first a gradual, and then a rapid decline of typhoid fever were
observed in the countries referred to, and notably was this the case in North
America.
In the Journal of the American Medical Association (January 24th, 1925),
comment was made on these phenomena, it being stated that " For some years health
officers in Great Britain—where elimination of drinking water infection antedated
by some years that in the United States—have been led to attach great importance
to shellfish infection as a factor in their own present-day typhoid." The writer
pointed out that" In London, in 1923, out of 173 typhoid cases, in which information
was obtained as to possible origin, fish or shellfish were held to have been at fault
in 59 instances, or more than one-third of the total." It might have been added
that, in another third, the disease was definitely found to have been notified in
error.
In the London annual report for 1921, attention was called to a most important
"Investigation of the pollution of tidal waters of Maryland and Virginia, with
special reference to shellfish bearing areas," by Hugh S. Cumming, which had
appeared some years previously. This report (Government Printing Office,
Washington, March, 1916) was, it was remarked, a fitting sequel to Dr. Bulstrode's
study of a similar problem in this country in 1896. In the London annual report
for 1924, attention was further called to the occurrence of two considerable shellfish
outbreaks in New York and Chicago during that year, and in this connection, the
comments of the American Journal (above referred to) were mentioned as being
of special interest. The American writer held the view that "sources of infection,
formerly submerged in a great wave of water-borne and milk-borne disease, can
now be seen rising as hidden reefs above the surface." Experience in London,
it was observed, suggested an alternative way of regarding the problem, considered
from the historical point of view; namely, that possibly some of the supposed waterborne
and milk-borne epidemics of the last century were really shellfish-borne ; and
such a consideration, if found to be valid, undoubtedly prompts exercise of special
caution as regards too ready acceptance of the water and milk origin of typhoid
fever at the present time.
These suggestions led to a particularly interesting rejoinder (Journal of the
American Medical Association, 6th March, 1926). The attempt "to interpret the