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47
MEASLES.
The epidemiological studies of the disease in the past have been almost exclusively based
on the mortality rates, and the disease not being notified, very little is known of its normal
prevalence measured by the number of attacks. Doubtless some of the increase observed
in the annual numbers is due to more complete recording of attacks, but not all. The
recorded mortality has been higher during the last four years than usual, and it appears
probable that there has been an abnormal prevalence during that period. The disease normally
exhibits regular epidemic waves at intervals of some eighteen months to two years, the
contrast between epidemic and non-epidemic periods usually being very marked. Such contrast
is wanting in the figures given above, i.e., since 1910.
Since 1903 the Department has made every possible effort to check the spread of disease,
and a suspicion has arisen as to whether the action taken has not resulted—as a first effect only,
it is hoped—in an interference with the natural course of the disease, whereby it has become of a
more strictly endemic character and less susceptible to epidemic explosions. Future experience
alone can furnish an answer to such question, and experience in epidemiology has an unpleasant
trick of upsetting preconceived theories. In the Appendix there will be found two tables
which have been prepared to show the course of this disease since 1903—so far as it can
be followed from the data available, admittedly incomplete. In the first of the two tables
(Table XI.) the numbers of cases reported week by week are set out. The different types
indicate the different degrees of epidemicity—"non-epidemic," "transitional," and "epidemic"
The degrees have been arrived at by taking the weekly average for the year (1909) of lowest
epidemicity as the standard of" non-epidemicity " (averaging less than 11 cases a week), and an
average of double that figure as the standard of " epidemicity." Periods with averages lying
between 11 and 23 have been regarded as "transitional." Two points will attract attention in
the table, the first, the high prevalence of the disease during the earlier half of each of the years
1908-13, and the second, the low prevalence and rarity of epidemics after the summer holidays
(29th to 34th weeks inclusive).
In the second table (Table XII.) an attempt has been made to summarise the information
contained in the former table by grouping the weeks according to the standards just described,
and to show the duration of each period and the average numbers of cases reported weekly in
them. It will be noticed that certain of the periods are blank, which means that the progress
from non-epidemic through transitional to epidemic and vice versd has been interrupted either
by the disease passing at once from the non-epidemic to the epidemic, or stopping at the middle
period to revert again to the first or third. The last four epidemic periods have been marked by
long duration and high averages. The end of the observation is characterised by a period of
exceptionally low prevalence.*
The morbidity of the disease last year was 8.71 per 1,000 persons of all ages, as compared
with 9.81 in 1912 and an average of 9.13. {See below.) Last year's rates were in striking
contrast with those of 1910. The morbidity rates recorded in the Wards are given in
Table 32.

* The last non-epidemic period lasted from the 32nd week of 1913 to the end of the 15th week of 1914—37
weeks in all—and was even then uninterrupted. The total number of cases reported during that period was 85,
giving an average of 2.2 cases per week, with a maximum of 7 cases in any one week and a minimum of zero
(11 weeks).