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14
In the diagram on p. 95 with a view to further study of the extent of interchange
in the earlier records between scarlet fever and diphtheria, comparison has been
made between the contours exhibited for London and New York when death-rates
from diphtheria and scarlet fever combined are plotted out. This diagram clearly
confirms the view that in the period, from the sixties to the nineties of the
last century, there was a much greater tendency to include cases resembling scarlet
fever as " diphtheria," in New York, than was the case at that time on this side of
the Atlantic. Comparison of the death-rates in this country, exhibited on the one
hand by London and the adjoining counties, and on the other by the Lancashire
towns, further suggests that in a somewhat similar way London has in later years
included certain types of cases as " diphtheria," which in some of the Lancashire
towns might perhaps have been classed as " scarlet fever." Furthermore, as noted
in the annual report for 1916 (p. 35), in London at an earlier period, i.e., for some
years after 1859, there seems to have been " a decidedly conservative tendency in
the matter of describing epidemic throat diseases, croup and diphtheria being still
distinguished from one another in London in the sixties and seventies, long after
the new designation diphtheria had been more generally accepted in other parts of
the country. Finally, " it may be taken as certain that at the crests of the major
waves, in London at any rate, the epidemic type approximates more nearly to what
may perhaps be styled the diphtheritic, and between the crests to what may perhaps
be styled the scarlatinal, type " (loc. cit.).
All these observations strengthen the impression that varying fashion as regards
nomenclature has played a great part in connection with these epidemic throat
diseases. It is perhaps for this reason largely that, in the sixties and seventies
and even into the eighties, diphtheria was regarded as a disease of the sparsely
inhabited rather than of the densely inhabited areas. In London it should be noted
however, as stated elsewhere (loc. cit. p. 35), that an epidemic wave had already
swelled in the late fifties, thus leaving the metropolis comparatively immune from
" diphtheria " in the two succeeding decades.
Then, from the sixties onwards, came the great increase of size of the towns,
the immigration from the rural areas, the freer movement of population, the spread
of compulsory schooling with closer aggregation of susceptible children, and the
extension of measures of isolation, disinfection and hygienic control generally.
Shortly afterwards, in 1883, the diphtheria bacillus was discovered, and its appearance
upon the scene naturally led to further alterations of fashion as regards nomenclature.
In the present century bacteriological methods have been more widely used
in London than in the country as a whole, and perhaps more extensively, too, in
London than in some of the northern towns. The diagram on p. 16 offers a certain
amount of confirmation of this view so far as London and the Lancashire towns are
concerned.
Having regard to these considerations it seems now, more than ever, important
to realise—-
(1) That regard should be paid to the close relation existing between
epidemic diseases variously described in past years as croup, laryngitis, diphtheria,
scarlet fever, cynanche maligna, etc., etc.
(2) That the tendency must be recognised, when sufficiently large populations
are passed under review, for epidemics of throat disease to occur in major
waves at intervals of some 30 years, and for the types of disease exhibited
at various stages of these epidemic waves to manifest varying phases.
(3) That study of the influence of any special preventive or prophylactic
measures against diphtheria or scarlet fever, in a particular town or tract of
country, during any year or series of years, needs to be very carefully conducted,
and that while closely scrutinising what actually happens, a critical eye should
ever be kept upon what might be expected to have happened independently of
the special preventive measures newly applied.