30
stables have boarded floors raised a little from the surface of the ground under which the
earth becomes much contaminated with filth and moisture, whereas the Government
stables have generally excellent asphalte floors with fair slope, surface drains, and are
generally kept in excellent order. But, although the stables being open at the sides
renders them less valuable as a protective means than they might be, we have ample
evidence that this defect is not in itself sufficient to generate the disease, in that D stable
fo the Somersetshire lines is by far the most exposed and at the same time is the most
healthy. The geological formation of the plateau on which the lines at Rangoon
stand is laterite; this bluish laminated formation is somewhat clayey and tends to check
percolation of water; thus on the plateau surface there are marshy patches, and much
water hangs there in monsoon time. The A troop mules used to be picketed out
here in the early mornings while their stable was being washed. As far as stable man-
agement goes, the Government mules both at Tonghoo and Rangoon have been better
treated than the majority of private animals in Burma. Related closely to the
question of locality in its effects on the disease is the fact that it has not yet been
observed at Thayetmyo or at Moulmein, and it is important to consider if those
places are intrinsically healthier, especially in relation to fever, than Rangoon and
Tonghoo. We must not jump prematurely to conclusions in this matter. Had
we been considering it only from last year's experience, we would have included
Tonghoo among the stations in British Burma healthy for mules, but we should
have been sadly in error. It is necessary to wait for two or three years longer
before we decide on the relative healthiness of stations for the mules; we have not as
yet sufficient evidence on which to base an opinion. Moulmein has hitherto been
tested with only a very small body of mules, and we have seen that the disease has
hitherto occurred only among mules collected in numbers. Thayetmyo has thus far
withstood this test; a large number of mules serving in it have remained healthy; it is
a place differing much in its climate from both Rangoon and Tonghoo. And we
must remember that we have a suspicion that some animals sent there sick recovered.
The balance of evidence is in favor of the view that Thayetmyo will prove a conve-
nient station and suitable for a large number of mules. We must not forget that the
Artillery mules at Tonghoo and the Sapper mules at Rangoon have entirely hitherto
escaped the disease.
25. The influence of season is worthy of especial attention, because of the fact that,
in so far as our experience at present goes, the deaths have specially occurred in
autumn and winter—in fact towards the end of the rains and in the cold weather, the
latter of which should be the healthiest time for animals. But, when we look more
closely into the facts of the case, we find that in most instances the disease is acquired
during the rains, especially in animals exposed to them, but cases seem to occur occa-
sionally and sporadically at all other times of the year. The advent of the rains in
tropical countries is associated with an extensive growth and development of low
organisms, especially fungi and their allies, which have been dormant during the
drought and heat of the hot weather. Thus, with moisture and heat, germs of various
sorts spring into activity, assuming their more active phases of development; then, in
the intervals between falls of rain each small pool becomes the centre of development
of minute life, and miasm arises from marsh, jheel, and stagnant tank ; pestiferous
mists prevail and active organic matter is washed down into tanks supplying drinking
water. At the same time the animal constitution, enfeebled by prolonged existence
in tropical heat and dryness, is rendered deficient in tone and resisting power by the
sudden occurrence of moisture in excess: in the atmosphere. "With such fertile sources
of fever germs we cannot be surprised if under-fed mules exposed in the open in the
jungle during monsoon time succumb to disease. We must now examine the several
elements of climate and see if we can find that any of them show marked and definite
relations to the outbreaks:—
(a) Barometric pressure in the Rangoon outbreaks has been in a curiously
direct relation to the number of fatal cases. This can be at once seen on
reference to the Graphic Record No. 2 appended. The rise in disease
curve (as deduced from the fatalities) is in direct association with the
rise in barometric pressure. We obtain similar deductions from an
examination of the conditions at Tonghoo.