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it would follow that in years of scarlet fever prevalence there would also be observed abnormal flea prevalence.
In the epidemic year 1914, the flea prevalence was, as a fact. slightly higher than in 1915.
If it be assumed that scarlet fever is communicated by the flea, by inoculation, it might perhaps be anticipated
that a series of years of high flea prevalence would be accompanied by high scarlet fever
prevalence, and succeeded by years of low flea and scarlet fever prevalences.
It was noted by Dr. Longstaff many years ago that there is a close relationship between cycles
of dry years and cycles of scarlet fever prevalence, and it is a matter of some interest to determine
whether there is any relationship between these cycles and cycles of flea prevalence. The records of
the latter relate as yet to only a few years, indeed only to the period covering the rise from the last low
prevalence of scarlet fever to the maximum of 1914, and the slight fall in the following year. As was
pointed out in last year's annual report (p. 57), " the conclusion may be formulated that broadly speaking
the curves of scarlet fever and flea prevalence for the period of six years show a tendency to rise together
from a low level at the beginning to a high level at the end of the period," and this correspondence
of movement is maintained in the slight fall of both flea and scarlet fever prevalences observed in 1915.
The seasonal prevalence of scarlet fever in England and Wales during 1915 showed no marked
difference from that of previous years. There was a maximum incidence in October and a maximum
about this time of the year is customary in this country. Examination of the records of foreign towns
shows, however, considerable variations in the time of year at which the maximum number of cases
occurs. In Paris, New York and other North American cities, and in Vienna the maximum falls in the
second quarter. In Berlin, Copenhagen, Christiania and Stockholm the period of maximum approximates
to that of London. In Australia scarlet fever is not prevalent to anything like the extent obtaining
in European countries, and complete records of notification for the whole Commonwealth are rot at
present available In Western Australia in the period 1909-1913 a maximum is attained in the second
quarter; and this seasonal maximum is more pronounced in years of higher incidence (1910 and 1912)
than in years of low prevalence. Diphtheria is far more prevalent relatively than scarlet fever
and the curves of diphtheria incidence in Western Australia show a pronounced maximum in the second
quarter. Generally speaking, the scarlet fever and diphtheria maxima occur at the same time of year.
Scarlet fever is practically non-existent in India. The relation, if any, of the period of maximum prevalence
to the period of maximum flea prevalence in different foreign towns awaits elucidation. Some
inquiry has been made in India in connection with plague, as to seasonal prevalence of fleas, particularly
rat fleas (see Plague Commissions Reports). Some curious differences in the time of prevalence of
plague are noted, e.g., Bombay and Poonah, though within a few miles of one another, have in certain
years suffered from epidemic prevalence at different times of the year. As regards Australia the maximum
of plague prevalence and the maximum of rat flea prevalence occurred in the early part of the year.
The data requisite for carrying the matter further are lacking at present.
In London it appears that in the poorer, i.e., the more densely populated districts, the range of
seasonal variation from autumnal maximum to spring minimum is considerably greater than in the
better class, and less densely populated, boroughs. In no town or area in which the seasonal variation
has been examined is so extreme a variation apparent as in the case of New York, and probably the
great density of population is the main cause of this phenomenon.
With regard to the geographical distribution of the human flea comparatively little precise information
is obtainable. Mr. H. Russell writes : " The nearest allies of the human flea, which are found on
various animals, are all inhabitants of the Old World. The indigenous fleas of America are only distant
relatives of Pulex irritans. Our knowledge of the present and former distribution of this species is
deplorably meagre. The many books of travel published in the early part of the nineteenth century
contain hardly any records of fleas. The human flea is now cosmopolitan. Specimens identical with
those from Europe are found almost everywhere. But it may be doubted whether this was the case
before the great era of travel and steam began in the last century,"
Side by side with this passage may be read the following excerpt from Clement Dukes' article on
scarlet fever. Under the heading " Geographical Range," he says : " The origin and native habitat of
scarlet fever are unknown ; nor do we possess any knowledge of the period when it first became prevalent
on the continent of Europe, so intimately was it confused with measles. From Europe it has extended
over most parts of the world, and more freely in later times, on account of the extension of commerce.
It appeared in Ireland in 1827, but not until 1847 in Greenland. Its presence in Africa and especially
in Egypt has been insignificant. and it is rarely found in Asia except on the coast of Asia Minor. In
India and China occasional sporadic cases only occur, and in Japan the disease is unknown. It reached
North America in 1735, but was absent from South America until 1829. Its final appearance in Australia
and Polynesia occured in 1848 : in New Zealand in 1854."
Diphtheria.
There was no appreciable diminution in the incidence of diphtheria during the year, the somewhat
marked prevalence of the disease during 1914 having been maintained throughout 1915. During the
year 51 schools were visited by school doctors for the purpose of examining suspected cases;
1,040 children were bacteriologically examined, of whom 133 were found to be harbouring diphtheria
bacilli, whilst in 53 further cases organisms not definitely distinguishable from the diphtheria bacillus
were identified.
History of a persistent carrier of diphtheria bacilli.—During the period of nearly six years covered
in the tabular statement (1910-1915) on page ,35 the child A, to whom reference has been made in preceding
reports, was an inmate of a particular residential school or of a fever hospital or other institution. She
has now left school, and the opportunity is therefore taken of placing her history on record. In 1910 she
suffered from scarlet fever and was duly removed to a Metropolitan Asylums Board hospital; shortly
after her return to school, a number of other cases of scarlet fever occurred among her schoolmates, and
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