NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
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By means of the following chart the seasonal prevalence of anopheles mos-
quitoes, of malarial fevers, and the rainfall in Mian Mir may now be compared:—
(Chart No. II.)
CI art No. II. Red line= curve of anopheles mosquitoes. (A culicifacies and A. Rossi.)
Upper black line=admission rate per 1,000 of British and Native troops (years 1892-1901).
Lower black line=Endemic indices of bazaar children (right hand figures, vide table on page 7).
Dotted line=Rainfall.
It will be seen from this chart that the seasonal prevalence of malarial
fevers in Mian Mir corresponds very accurately with the prevalence of anopheles
mosquitoes.*
In 1902 the first anopheles mosquitoes (A. culicifacies) were found in the
houses on May 20th. The first slight rise in the endemic index, i.e., the
commencement of the season of new infections, was noted a month later, which
(allowing ten days for the parasites to develop to the sporozoite stage in the
mosquito and twenty days for the incubation period in man) is the earliest time
* It will be noted on comparing charts I and II that the fever curve is dependent on the seasonal pre-
valence of A. culicifacies rather than on that of A. Rossi, for the latter species does not commence to be
prevalent until new infections have already begun.
C 2
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at which new infections could occur. During August, September, and October
the abundance of anopheles mosquitoes and the endemic index of the bazaar
increased together, and in November with the almost sudden disappearance of
adult anopheles mosquitoes the endemic index quickly fell.
As further illustrating the close connection which exists between the
prevalence of malarial fevers in Mian Mir and the presence and relative abund-
ance of anopheles mosquitoes, the conditions found in different bazaars and
followers' lines may be given in more detail. The inhabitants of these bazaars
live in exactly the same class of house, derive their drinking water from the
same source, and are exposed to the same climate and temperature. They are
in fact under precisely similar conditions except that the bazaars or lines are at
different distances from breeding places of anopheles mosquitoes. As would be
expected, the number of adult insects of this genus that can be caught in the
different bazaars and lines varies with the distance from a breeding place. It
will be seen from the following table that the prevalence of malaria is least in the
lines that are furthest from a breeding place and where consequently fewer
anopheles mosquitoes can be found, and greatest in the lines that are nearest a
breeding place and where a large number of anopheles mosquitoes are present.
Table showing the influence of breeding places of anopheles mosquitoes on
the prevalence of malaria in Mian Mir.
Name of locality.
Distance of nearest
breeding place and its
character.
Species of anopheles found and
abundance.
Endemic
index.
Spleen rate
per cent.
British Infantry
Bazaar.
Irrigation watercourse
30 yds. Pools 40 yds .
A. culicifacies
Abundant
52
8 0
A. Rossi
A. fuliginosus
Rare
A. pulcherrimus
A. nigerrimus
Royal Artillery
Bazaar.
Irrigation watercourse
172 yds. Pools in
bazaar.
A. culicifacies
Not very
abundant.
Abundant
35
75
A. Rossi
A. Stephensi
Scanty
A. pulcherrimus
Syce lines (A)
Irrigation watercourse
125 yds.
A. culicifacies
Abundant
5 6
4 8
A. Rossi
Syce lines (B)
The same watercourse
as for syce lines (A),
584 yds.
A. culicifacies
Scanty
2 0
2 0
A. Rossi
An experiment which I carried out during the year and which will be again
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referred to in the account of the operations, also illustrates in a remarkable
way how entirely the prevalence of malaria is influenced by the presence or
absence of anopheles mosquitoes. This experiment was the removal of the
inhabitants of the syce lines (A), referred to in the above table, into tents on a
n e w s i t e ¾ o f a m i l e f r o m t h e n e a r e s t i r r i g a t i o n w a t e r c o u r s e a n d 6 0 0 y a r d s f r o m
any pool. No anopheles mosquitoes were ever found in these tents and the
result of the experiment was the reduction of the percentage of infected children
from 56 at the height of the fever season in 1901, to 4 at the same time in 1902.
Only two forms of the malarial parasite have been met with in Mian Mir,
viz.: the Benign Tertian and the Malignant Tertian forms. Out of 26 infections
occurring in native children 40 were with the Benign Tertian parasite and 26
with the Malignant Tertian. Among the European troops the proportion of
Simple to Malignant Tertian infections is greater than this. Out of 18 infec-
tions among the men of the Royal Artillery in November 1901, 14 were with
the Simple Tertian parasite and 4 with the Malignant Tertian.
No Quartan parasites have been found in Mian Mir.
The foregoing account refers to Mian Mir as a whole, but it was not con-
sidered advisable to attempt to deal with so wide an area as the whole canton-
ment in our experimental operations. The area occupied by the Royal Artillery
lines, which are more or less isolated from the rest of the cantonment, was there-
fore selected, and it is now necessary to add a few details regarding the condi-
tions under which malaria prevails in these lines.
I.— The sources of infection of anopheles mosquitoes in the Royal
Artillery Lines.
It has already been shown that a high percentage of the young children
in the various bazaars and followers' lines are infected with malarial parasites, and
as these children receive no treatment whatever, it may be assumed with
certainty that they form the chief source from which anopheles mosquitoes
become infected.*
In the Royal Artillery Lines there are five principal sources of this nature,
v i z : —
(1) The Syce Lines of the Right Battery. (Fig. 1. A.) The infection of
children in these lines is between 50 and 60 per cent., and the distance of the
lines from the barracks is 150 yards.
(2) The Hospital followers' lines. The infection of children in these lines
is about 50 per cent., and they are situated within thirty or forty yards of the
hospital and prison.
*For further reasons of this fact see " Malaria in India," by Captain S. P. James, I.M.S. (Scientific
Memoirs by Officers of the Medical and Sanitary Departments of the Government of India, New Series,
No. 2), pages 61 and 89.
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(3) The Syce Lines of the Left Battery. (Fig. I. B.) The infection of
children is 20 per cent., and they are situated 400 yards from the barracks.
(4) The Royal Artillery bazaar. The infection of children is 35 per cent.,
and it is situated 440 yards from the barracks.
(5) The Servants' quarters in the officers' bungalows. A large percentage
of the servants' children who live in the bungalow compounds are infected with
parasites, and they form a dangerous source of malarial infection to the Europeans
living in the bungalows.
Fig. I. Showing the chief sources from which anopheles mosquitoes become infected in the Royal
Artillery Lines at Mian Mir.
II.—The carrier of infection in the Royal Artillery Lines.
All the species of anopheles mosquitoes previously mentioned, except A.
nigerrimus, are found in the Royal Artillery lines. As in other parts of the
cantonment A. Rossi is by far the most abundant, and enormous numbers of
this species can be caught from July to November in the houses of the bazaar and
lines, in the barracks, hospital, and prison. A. culicifacies is also abundant
throughout the lines, and adults of this species can be easily caught in the
bazaars and barracks. This is undoubtedly the species by which infection is
chiefly, if not entirely, carried in Mian Mir. The other species of anopheles.
mosquitoes referred to, are very rare in the Royal Artillery lines.
A Plan of Royal Artillery Lines at Mian Mir showing the irrigation watercourses and other anopheles breeding
places (in red), P. P. the brick lined watercourse.
No. 659). Print., India.—Oct. 03.
—1,154.
Litho., S. I. O., Calcutta.
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The breeding places of anopheles mosquitoes in the Royal Artillery lines.
In most stations the breeding grounds of anopheles mosquitoes during the
rainy season and those during the dry season can be sharply marked off , from
each other, but owing to the flatness of the ground in Mian Mir, and to its
impervious nature, a slight shower of rain produces almost the same conditions
as regards the presence of breeding places, as in other districts are produced only
during the true rainy season. At almost any time of the year, therefore, numerous
rain-formed breeding places may exist in Mian Mir, and it will be better for this
reason to enumerate all the places where anopheles larvæ have been found at
any time during the years 1901 and 1902, indicating at the same time the
relative importance of each breeding place. (See plan of Royal Artillery Lines.)
(1) The larger irrigation channels ("Rajbahas ").
(2)The irrigation watercourses.
(3)Water spread over the gardens and fields for irrigation purposes.
(4)Pools left in the bed of an irrigation watercourse when the
supply of water has been cut off.
(5)Pools formed by overflow of the irrigation watercourses.
(6)A few large ponds or " tanks " and a large number of small
stone reservoirs for collecting water in the gardens.
(7)Rain-filled pools, surface drains, rain-formed pools on flat areas
of ground, etc.
(8)Domestic utensils, viz., tins and buckets of water kept in the
lines in case of fire and for other purposes.
(9)The swimming baths.
(10) The small surface drains, which carry off water from the stand-
pipes, wells, cook-houses, baths, etc.
(11) The wells.
1. The larger irrigation channels. The velocity of the water in the main
canal (Rajbaha) bringing water into the Royal Artillery lines is considerable, and
except in the comparatively still water near the bridges, larvæ can rarely be
found.
2. In the smaller distributing channels, however (irrigation watercourses
or "cuts"), which form a network throughout the cantonment, the flow of water
is slow and is frequently further impeded by a thick growth of grass and
vegetation along the sides of the watercourse.
Many of these ditches also have no outflow, and end in the basin of
a Persian wheel, so that the water in them is quite stagnant except during the
time that the Persian wheel is working ( about three hours daily). All these
irrigation watercourses form excellent breeding places and are the main source
of anopheles mosquitoes, especially of A. culicifacies, i n t h e c a n t o n m e n t .
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Many larvæ can as a rule be found in them throughout their length, but they
are especially numerous in places where grass and weed are growing at the
edge, and also at the bridges where the flow of water is checked.
3. The water distributed over the land dries up quickly as a rule, but even
in this, dangerous breeding places of anopheles mosquitoes are sometimes found.
The young trees in Mian Mir are planted along the bed of small distributing
ditches, and pools of water are formed round the roots of each tree. These pools
are frequently so deep that all the water given to the trees in one day does not
dry up before the next supply comes on the following day, and I have frequently
found anopheles larvæ and pupæ in them. Similar pools are formed in many
parts of the gardens of the officers' bungalows owing to the unevenness of
the ground. The supply of irrigation water to the cantonment is a very inter--
mittent one, and during the comparatively short period in which it is available,
every one endeavours to flood their gardens as much as possible. Owing to
the impervious nature of the soil and to the general flatness of the ground, if
more water is given to a garden than can all be soaked up in a day, it collects
and forms pools in any depressions of the ground. These pools, being replenished
daily, may last for ten days or more.
4. When the irrigation water-supply is cut off from the cantonment, many
pools are left in the watercourses. The number of larvæ found in these pools
varies considerably. In many of them no larvæ can be found, in others, how-
ever, larvæ are so numerous that the surface of the pool is almost covered with
them. In the winter these pools are of great importance, for during December,
January, and February, when the irrigation water-supply is cut off for long
periods at a time, anopheles larvæ can remain in a resting condition in pools
under the bridges until the warm weather comes again. This is in fact the
chief, if not the only, means by which some species of anopheles mosquitoes can
tide over the cold of winter in Mian Mir. During the cold winter months no
adult anopheles mosquitoes can be found in the houses, but in such pools as
these, larvæ are found in a more or less hybernating condition—that is, they do
not grow at all, or grow extremely slowly, until the warm weather comes again.
5. Numerous pools are formed by overflow of the irrigation watercourses,
and large numbers of larvæ ( A. Rossi) are found in these. Occasionally from
the breaking down of the side of a watercourse a very extensive overflow is
made, forming a pond which may last for some months.
6. In the brick-lined tanks for bathing purposes which are found near some
of the bazaars, larvæ are rarely present, but there are also a few ponds, the sides
of which are not brick-lined, and in these, anopheles larvæ are not uncommon.
In every garden there are a number of small brick tanks for collecting water for
irrigating purposes. They frequently contained anopheles larvæ.
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7. Rain-formed pools are exceedingly numerous, and it is diffícùlt to realise
the difference which even a small shower of rain makes in the aspect of the can-
tonment. Large ponds of water cover the plain on every side, and for two
days after a few hours' rain, evolutions on the Royal Artillery parade ground be-
-
come impossible. To reach the syce lines of the batteries one has to wade
through water, for several hundred yards. The whole cantonment is in a similar
condition:
Most of these large sheets of water dry up under the hot sun in two or
three days, but pools remain in depressions of the ground and in all the
surface drains until the next shower of rain. The condition, indeed, is one
of the presence of innumerable pools constantly exposed to a hot sun and
con-
stantly being replenished with fresh water ; a condition eminently suitable for the
breeding of anopheles mosquitoes. It is not surprising, therefore, that in all
these pools and in all the surface drains numerous larvæ are found during July
and August.
8. Two large covered-in swimming baths for the troops are present in the
Royal Artillery lines. Although these are constantly used. by the men, numer-
-
ous anopheles larvæ were found in both the baths during the summer. The baths
take about two days to empty and nearly a fortnight to refill, and the water in
them is not completely changed more than three or four times during the whole
summer.
9. The waste water from the wells, standpipes, cook-houses, and, baths is
carried off in small brick channels two or three inches deep. In all of these
channels anopheles larvæ were found at different times of the year.
10. Numerous tins and earthenware vessels of water are kept in the lines
in case of fire and for other purposes. They frequently contained large
numbers of anopheles larvæ.
11. As a rule, anopheles larvæ were not found in the wells, but they were
present in a few which are only occasionally used.
The above is a brief description of the conditions under which malarial
fevers prevail in Mian Mir, and I shall now describe the operations which have
been undertaken for their prevention. It should be noted that the primary object
of the operations was to test the efficacy of mosquito destruction, and the chief
efforts have, therefore, been directed to this end.
In an experiment such as this, it is necessary to have some definite tests by
which success or failure can be measured.
1. Tests of a reduction in the number of anopheles mosquitoes.
(a)Larvæ. It can be made evident that though in previous years
larvæ were readily found, yet in the year of the experiment they
were not so abundant.
(b) Adult mosquitoes. It is possible for an observer who has
regularly collected anopheles mosquitoes in any, given bazaar or
barrack to ascertain with certainty whether they are more or less
abundant in the year of operations than in previous years. It is
also possible to ascertain whether anopheles mosquitoes are
more or less abundant in the houses within the area of operations
than in those outside it.
2. Tests of a reduction in the amount of malaria.
(a)A reduction in the number of admissions for malarial fevers
among the troops.
(b)A reduction in the percentage of infection with malarial parasites
among the troops.
(c)A reduction in the amount o malaria in the regimental bazaars
as measured by the percentage of children found infected with
malarial parasites.
The first of the tests of a reduction in the amount of malaria is probably
the least to be depended upon, because hospital statistics may be affected by
many causes ; still unless it were possible to show a marked reduction in the
number of admissions into hospital for malarial fevers, the operations could not
be considered successful. The most conclusive test of all would be the reduction
of the percentage of infected children in the regimental bazaars. If, as a result
of the operations, it could be shown that a marked reduction in the number of
anopheles mosquitoes, and in the percentage of infected children in the regi--
mental bazaars, had occurred, the success of the operations would be proved.
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PART II.
The operations were commenced on the 2nd of April 1902. They may be
described under the following headings :—
(1) Operations directed towards the destruction of anopheles mosquitoes.
(2) The removal of a number of infected people to a distance from the
breeding places of all mosquitoes, and away from the vicinity of
the barracks.
(3) Operations directed towards the destruction of malaria parasites in
infected individuals by subjecting such individuals to continuous
quinine treatment.
(4) The administration of prophylactic doses of quinine to the troops.
I.—Operations against mosquitoes.
In order that all parts of the area chosen ( viz., the Royal Artillery lines)
might be systematically examined and dealt with week by week, I divided it for
the purposes of the work under the following plan :—
(1) The irrigation watercourses, viz., the main irrigation channel and its
six chief branches, called respectively the first to the sixth
branch, with their offshoots, which supply the whole area of the
Royal Artillery lines.
(2) The " Royal. Artillery bazaar section " comprising the bazaar and the
area surrounding it.
(3)The " Barracks section " comprising the area round the main barracks,
the hospital, and prison.
(4)The " Stables section " comprising the area round the stables, syce
lines, etc.
(5)The " Gardens section " comprising the area of the officers' bunga-
-lows and gardens.
(6)The "Pools section " comprising all the areas containing more or
less permanent pools.
One or more of these sections were carefully examined daily in regular
order, so that no part of the lines conld be left unexamined and unoperated upon
for more than a week at a time. It was not possible of course to examine the
Whole of the watercourses in one day, but by taking one watercourse and the
section near it, e.g ., the 1st branch and the bazaar section, the same day, and
the 2nd branch and the barracks section the next, and so on, the whole of the
area could be gone over during the week.
D2
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Methods employed.
These were principally confined to operations against larvæ. The methods
used in the irrigation watercourses (running water) and in pools and other
collections of stagnant water must be described separately
.
(1) Methods employed in the irrigation watercourses.
(a) It has already been pointed out. that the irrigation watercourses form
the chief Source of anopheles mosquitoes (especially of A.culicifacies )
in the Royal Artillery lines, and that the larvæ are most numerous in
these channels wherever any grass or weed is growing at the edges.
Experiments which we had made in November 1901 pointed to the
fact that if the sides of an irrigation watercourse are cut clean and
smooth so that the flow of water is not impeded, and if all grass and
•
weed under.which larvæ can shelter is removed from the edges, the
number of larvæ found in such a watercourse is greatly dimin--
ished. The chief method employed was, therefore, based on this
fact, and it was hoped that by constantly keeping the sides of the
watercourses smooth and free from grass for many months, they
might be made permanently unsuitable for the breeding of anopheles
•
( b) A more effective and permanent means of carrying out the above
principle was to have one of the watercourses lined With brick and
smoothly plastered with cement. This was done with a length of
watercourse running through the centre of the lines and in front of
the main barracks and hospital. (Plan of R. A. lines. p. p.1)
(c) For some weeks during June and July I tried the method of drying
out and cleaning each branch, once every ten days. In this way all
the larvæ present in the watercourse were killed before they had time
to reach the pupa stage, but on account of the expense of drying out
the channels—for most of the water had to be baled out with
buckets,—and the fact that the stopping of the water interfered to
some extent with irrigation, the method was discontinued.
(d) The method of pouring oil on the watercourses.
I have already mentioned that many of the watercourses contain almost
stagnant water, and for these the plan of destroying the larvæ with kerosene oil
naturally suggests itself.
Some experiments that I made upon a plot of grass-land and lucerne, kindly
lent me for the purpose by the Officer Commanding the Royal Artillery, showed
that even large quantities of kerosene oil poured round the roots of the grass
had no injurious effect whatever, nor did it give any bad, taste or smell to the
2
grass; but in spite of these experiments I consider that it would be very inad-
visable to use a method from which there would be a danger of any kerosene oil
reaching the crops. Nor do I think it would be advisable to use a preparation,
such as "larvicide," which colours the water red.
If in any year the crops were poor it, would certainly be ascribed by natives,
and even by many Europeans, to the use of either of these methods.
With proper precautions, however, it is quite possible in certain places to
pour kerosene oil on the watercourses without any of it reaching the land ; and
on this point my experiments showed the following results :
—
(I) Kerosene oil poured on a watercourse between any two bridges does
not pass beyond either. This is due to the fact that the bridges
over the watercourses in Mian Mir are what are called "syphon
bridges," that is the depth of water in the watercourses is always
greater than the height of the arch of a bridge, so that, as the oil
floats only on the surface of the water, it cannot pass through the
arch of the bridge. This is illustrated in the diagram below
(Fig. 2) in which it is seen that oil poured on the stretch of water
between the bridges A and B cannot pass through the arch D to
reach the stretch of water between the bridges B and C.
Fig 2.
A, B, C, Bridges over a watercourse. D, Height of arch of bridge. E, water level. The arrows
indicate the direction of flow of the water.
(2) For the same reason if a deep board is placed over the mouth of a
Persian wheel, half the board being under the surface of the water
and half above it, oil can be safely poured on the watercourse with
- o u t a n y e n t e r i n g t h e
j a l a h a r
i t s e l f .
(3) The water-supply to the canals is frequently shut off for a week or more
at a time. When this is done numerous pools are left in the