5
The method adopted, which is a modification of that adopted by Major
Christophers, is as follows :—
Epidemic malaria of the nature now under consideration is entirely an
autumnal phenomenon, usually exhibiting its greatest effect on the fever mor-
tality during the month of October. The fever deaths for this month for the
year under review are therefore calculated in the case of each municipal town,
notified area and thana. The average monthly mortality from malaria for
the months of April, May, June and July of the same year is then worked out
for each area. These two figures are then cast in the form of a fraction of which
the numerator is the October mortality and the denominator is the average
fever mortality for the period mentioned above.
Thus—
Recorded Fever Mortality for October.
Average monthly Fever Mortality for April, May, June and July
160
=
= 10 (epidemic figure).
16
In this manner the epidemic figure for each municipal town, notified
area and rural circle (thana) may be worked out, and by placing these figure's
in their appropriate area on a map of the Province the distribution of the epide-
mic becomes accurately known.
Further by the use of different colours for epidemic figures of certain
magnitudes it is possible to display in a graphic manner the relative degree of
severity of the epidemic in different areas.
When this is done for the year under review it is found that in many dis-
tricts the epidemic figure does not exceed 1, indicating that the number of deaths
in October 1.913 did not exceed the normal number. Epidemic figures of from
1 to 5 may be considered to represent an increased mortality due to the normal
autumnal recrudescence of the disease, and such being the case it is clear that
autumnal malaria was even less prevalent than usual over a large part of the
Punjab during 1918,
In the districts of Gurgaon, Hissar and Rohtak, for example, where a
partial failure of the monsoon was experienced, the epidemic figures were
consistently low, being with few exceptions 1 or less. The only area in which
the epidemic figure was 5 or more throughout the Province was the town oí
41
Eminabad in the Gujranwala District where the epidemic figure was — =
4
10.25 E. F. The circumstances under which this isolated epidemic occurred
have been investigated. It was found that the epidemic was not entirely con-
fined to the town but affected to some extent a portion of the thana (Kamoke)
in which it is situated, with the result that the epidemic figuro of the latter
was raised to 3.5 and the spleen-rate of children under 10 years of age to
47 '7 per cent. It was also discovered that the severe epidemic in Eminabad.
coincided with the opening of a new canal in the vicinity and with the local
cultivation during the period from June—October 1913 for the first time of rice
crops.
But in view of the fact that the rice fields are situated at ¡a distance of
more than half a mile from the town, that the epidemic did not affect all the
areas supplied by the new canal, and that a similar epidemic of exactly equal
severity, so far as mortality is concerned, occurred in 1908 (when no canal
existed) there is reason to believe that the opening of the latter had little or
no influence in producing the epidemic. On the other hand, the occurrence of
local flooding as the result of defects in the drainage system which takes the
rain-water from the Kashmir hills was thought to he of greater significance.
The investigation of Eminabad exemplified in a striking manner the
importance of calculating " epidemic figures," and it also demonstrated the