NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
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degree of controlling malaria in the great districts and provinces of
India.
Not only have all successful anti-larval campaigns been asso-
ciated with the free use of quinine, but they have in every case dealt
with comparatively insignificant populations, in some cases with
communities no larger than those to be found upon a single tea
garden; and they have involved comparatively enormous expense
reaching in some cases several pounds sterling pel head of the popu-
lation.
It is impossible to argue from such examples the probable effects
of large drainage operations or measures directed against the mos-
quito alone, and we have already shown how small a relation mere
numbers of anopheles often bears to the prevalence and intensity of
malaria when conditions unfavourable to the human host are present
in a marked degree.. This being so, it is impossible with our present
knowledge to be certain that the inauguration of vast drainage
schemes at a cost of crores of rupees will have the slightest appreciable
effect in reducing malaria in Bengal ; and it is quite possible, on the
other hands, that without the most careful control of the conditions
relating to the employment of labour on such undertakings grave dan-
ger may be incurred, and this very measure far from reducing malaria
may, for a time at least, serve actually to increase and intensify it;
while the larger the scheme, the greater would be the risk arising from
uncontrolled aggregation of the labour necessary for the performance
of the work.
As to the repeated statement that drainage of a country
must necessarily produce a mitigation of malaria by reducing the
numbers of anopheles mosquitoes, we may surmise, bearing in mind
Celli's definitely-expressed opinion regarding the Roman Campagna as
well as our own experience in India, that the improvement that
follows such operations may often be largely secondary in nature
and bound up to a great extent with the permanent settling of
populations and other conditions favourably affecting the human
host.
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With the conclusions we have formulated above we see adequate
reasons why the Duars should be malarious; and we can see that
in attempting to control the malaria it would be a mistake to
take too narrow a standpoint in our estimation of the conditions
involved.
II—THE DUARS AND MALARIA.
The Duars, as popularly understood, is a portion of terai land stretch.
ing for about ninety miles along the foot of the Eastern Himalayas. It
extends at most fifteen miles from the foot of the hills and in total area
does not exceed a thousand square miles. But in spite of its small ex.
tent it is one of the chief of the tea districts, producing more than one*
fifth of the tea produced in India. Otherwise this distirct is of little im-
portance since it possesses no townships and few villages of any size ;
in fact, but for the land which has been cleared for tea cultivation, it is
almost entirely forest and jungle.
In official matters the Duars includes more extensive portions of the
thanas of Dam Dim, Mainaguri, and Phalakata ; but the southern por-
tion of these thanas, composed of rich agricultural and thickly populated
by Rajbansis and other cultivators, has little in common with the
northern or tea-growing portions with which we are concerned.
Scattered throughout the district, but most closely aggregated in the
western portions, are the various tea gardens. The gardens, like those
of Assam, are large and are worked by various tea companies, only a few
small gardens being owned by resident planters.
The gardens number about one hundred. All but about a dozen
•of these have European managers and from one to four or even more
European assistants. In addition each garden employs a certain num-
ber of Bengali clerks or other subordinates, and upon each garden (living
in lines) is a considerable coolie population. These populations, in-
cluding men, women and children, are rarely below one thousand in
number and on larger gardens consist of from four to six thousand per-
sons.
It is these lines which form the villages, so to speak, of the tract
under discussion, and the garden populations which, taken collectively,
constitute for all practical purposes the population of the Duars. There
are, it is true, a certain number of aboriginal Meches still living in the
Duars, but these have almost disappeared from the western
portions and are only found in any number to the east where tea culti-
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22
vation has as yet not claimed so much of the country. Independent
colonisation by old tea-garden coolies also exists but the " bustee "
population, as it is termed, forms but a small item in comparison with
the garden labour,
Malaria is rife throughout the whole coolie population, and the
general impression that we have gathered is that it forms the one im-
portant disease influencing the tea industry in the Duars.
The condition as regards malaria among the aboriginals is
interesting, but cannot be considered as forming an important
part of the problem to be investigated. The interest attaches chiefly
to the question as to whether the Meches being the original inhabit-
ants of the country suffer from fever to the same extent as the immi-
grants. Briefly we may say that to a large extent they do. But the
Duars being malarious, apparently not so much because of its physical
features as by reason of the state of affairs brought about by the open-
ing up of the country, one must look upon the aboriginal Mech as now
quite as much a stranger to the existing intense malaria as any im-
migrant. The condition in the independent " bustee " colonised by
old tea-garden coolies we shall refer to later.
ESTIMATION OF THE AMOUNT or MALARIA.
Since there are no hospitals, and the cases of sickness recorded on
the gardens do not. as we shall show, bear any real relation to the amount
of malarial disease, we are confined, if we wish to estimate the amount
of malaria, to such general methods of estimation as—
(a) The endemic index and the spleen-rate.
(b) The amount of infection and the degree to which enlarged
spleen prevails among the adult population.
(c) The effects of malaria as shown by the amount of sickness and
death and the general effect of the disease upon the com-
munity.
The endemic index and spleen-rate.—The percentage of infected
children was shown in 1901, on those gardens visited by the Royal
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Society's Commission to be more or less uniformly high. We have ex-
tended these observations to a considerable proportion of the total gar-
dens and have found that the amount of infection noted can be stated to
vary very little throughout the Duars. In a large number of estimations
involving the examination of many hundred of children we have only
twice found the endemic index below 50 per cent., and in the vast major-
ity of cases it approximated very closely to 100 per cent. The spleen-
rate has never been less than the endemic index. These points will be
demonstrated by the tabular statements of our results given in Ap-
pendix I. Specially noteworthy is the maintenance of this high rate
of infection through some seven months of the dry season and its
presence on a number of gardens so situated as to appear extremely
unfavourable to the existence of even a moderate amount of malaria.
Race appears to play but little part in influencing the prevalence
of infection, though some races appear to be more profoundly affected
by the disease than other. In several instances where we have examined
the children of hill and plains people living on the same garden under
similar conditions, but with the two races widely separated, we have
found the rate of infection and of enlarged spleen to be practically the
same in each case. As a general rule, however, more actual sickness
due to this disease is seen among the hill people than, for example,
among natives of the Ranchee and Hazaribagh districts.
Adult malaria.—Malarial infection in the Duars is not confined to
the children, but affects profoundly a considerable proportion of the
adults. This is especially so in the case of new coolies, most of whom
come from comparatively non-malarious districts and are quite different-
ly circumstanced as regards malaria to indigenous adults in a malari-
ous country, who have been immunised to malaria during childhood.
The extent to which adult in the Duars suffer from the disease will be
gathered from facts given in the chapter on" Sickness in the Duars."
VARIETIES OF THE PARASITE.
All three forms of the parasite, quartan, simple tertian and malig-
nant tertian, are almost equally common, though simple tertian infec-
tions slightly preponderate.
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A certain amount of variation occurs in the seasonal distribution
of the different species. On the lower gardens in the rains infection
with the malignant tertian parasite becomes prominent; but as the dry
weather advances this parasite tends to become less conspicuous and, to-
wards the end of the dry and cold season quartan infections predominate.
Very often we have been struck with the existence of groups of
infections by one or other variety, a condition particularly noticeable in
the case of quartan forms.
Mixed infections are exceedingly common if not the rule ; though
generally at the time of examination parasites of one or other species are
in the majority.
How MALARIA SHOWS ITSELF.
Malaria in a native population'does not confine itself to causing
attacks of " fever ", and a due appreciation of its effects under such
circumstances is very necessary.
Child malaria.—Very young children are 1 usually fat and healthy,
with normal blood free from parasites. They soon, however, begin
to get serious attacks of fever, and, at an age of from six months to two
years, it is very doubtful if one child in many hundreds will be found
whose blood is not more or less thin and watery and whose whole phy-
sique is not modified by malaria. Whatever intercurrent disease or
symptoms such children may eventually exhibit, it is certain that
malaria is the primary cause at work in bringing about'their death. In
sonic instances seen by us malaria seems responsible for the almost
complete absence of children among certain communities, nearly
every child dying within a year or two of its birth.
Coolie ancemia.—Though adult coolies shortly after they first enter
the district may be found exhibiting the typical clinical symptoms of
acute malaria, they soon present an entirely different picture in which
" fever " is subordinated to intense anaemia. Such anaemia is apt to
suggest anchylostomiasis, but in the Duars it is nearly always malarial
in origin.
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Dysentery.—Most adults dying from malaria exhibit the most intense
anæmia, oedema of the face and ankles or more or less general dropsy
and a form of terminal dysentery. Dysentery in such a connection can-
not rightly be considered as the real cause of death, though it is fre-
quently returned as such.
Abortion.—Pregnant women are particularly liable to abort as a
result of acute attacks of fever or as the result of the intensely anæmic
condition that we have described. In the latter case large numbers of
women abort or die before or immediately after childbirth, and even
when the child is born at full time it is small and ill-developed, and very
frequently it is beyond the powers of the mother to nourish it. The ex-
traordinary number of abortions under such conditions has given rise
to the impression that criminal abortion is frequent, an idea but little
supported by actual observation.
General apathy.—We have not infrequently heard it said that
" laziness " is responsible for many coolies not working and that this
in turn makes them sick and anæmic. This is an inversion of the
real facts. A marked feature of the chronic malarial subject is a
characteristic apathy, and it is easy to understand that when, as is very
frequently the case, the percentage of hemoglobin falls to below 25 per
cent, of the normal the subject becomes apathetic, unwilling to work,
and there commences the vicious cycle that often ends in death.
General unrest and movement of the population.—Where, as in the
Duars, malaria is intense, family bereavement and constant ill-health,
interference with means of livelihood and resulting hardship to depend-
ents, together with a host of other effects resulting indirecly from the
same cause lead to a constant state of shifting in the population.
Movement from garden to garden in the Duars is extraordinarily fre-
quent and seems to be due to a state of unrest produced by a want of the
sense of well-being.
THE EFFECTS OF MALARIA.
In the Duars we see exemplified all the effects of intense malaria.
These may be briefly summarised :—
(a) An abnormally high death-rate and a diminished birth-rate,
not only preventing the; natural increase of the population,
ISC
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"but causing an actual decrease hidden only "by constant
immigration. (Vide Chapter VIII, Vital'Statistics.)
(5) -Difficulty in getting sufficient labour; restriction of the neces-
saiy recruitment of labour to areas inhabited by specially
hard) races ,' excessive recruiting to keep up the labour
force ; and poor efficiency even of the labour force main-
tained.
(c) A very small degree of true colonisation and the general per-
sistence of temporary conditions.
(d) General backwardness of the district, due to sickness and
death among Europeans and their Bengali Staff; avoid-
ance of the area by all who are not forced to enter it;
interference with all branches of the public' service as well as ;
of private enterprise owing to sickness, and difficulty in
maintaining a good class of subordinate, and other condi-
tions- which hinder progress.
GENERAL CHARACTER OF THE PREVALENCE OF MALARIA IN THE DUARS.
The state of exalted malaria which we have described resembles
a permanent condition of epidemic malaria. Such a condition we may
for convenience term HYPER ENDEMICITY.
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III.—ANOPHELES IN THE DUARS.
Anopheles are very prevalent in the Duars during the rains and for
some months after. Their breeding places are chiefly connected with the
small streams so characteristic of thedistrict. These streams are remark-
able for the extreme variation they undergo at different seasons of the
year, and as a result of continuous rain, floods, and changes in their
beds. Most of the streams, especially those in the northern portion of
the district, flow upon beds of roughly tumbled boulders. In the rains
they become torrents ; but in the dry season they rapidly shrink to
trickling rivulets or chains of small pools, eventually in the majority of
instances becoming entirely dry. Owing to the porous nature of their
beds they may be found sometimes with running water in one part of
their course and long dry portions at another. The stream beds are
often several hundred yards in width ; or where an old deserted channel
of one of the larger streams is concerned, they may be half a mile or
more wide with tumbled boulders, jungle and a net-work of rills fed
from innumerable springs. In many of the tea gardens the streams run
in a sinuous manner at the bottom of deep precipitous ravines filled
with more or less dense jungle. In the low-lying tracts the streams
possess muddy or sandy bottoms and sedgy edges, while the current is
more sluggish ; and streams of this nature generally persist throughout
the dry season. In a few gardens there are almost stagnant perennial
water-courses of considerable depth winding through the land.
Where lines of springs issue or where there are many deserted river
channels small swamps are common. The more extensive of these are
often used for rice cultivation ; but many are filled with rank vegeta-
tion and jungle. One or many small streams usually flow through
them, and these invariably contain the larvæ of M. listoni., N. theolaldi
and other species.
Other breeding places of very varied nature also exis't, the most
important being rice-fields, large pools, borrow-pits and kutcha wells.
Garden drains also often form breeding places. None of these, however,
are so important as regards breeding of anopheles as the streams and
swamps that we have mentioned as being so characteristic of the
district.
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SEASONAL VARIATION IN THE BREEDING PLACES OP ANOPHELES.
Early in the year until the rains begin to fall in May or June, breed-
ing places are scanty and widely separated. All the smaller streams are
dry and many of the larger ones contain but little water. At this time
large areas are absolutely devoid of surface water of any kind. The
first showers of rain have no appreciable effect, sinking rapidly into
the dry and porous soil, and though several inches of rainfall may be
recorded, the streams do not run, nor are any permanent surface pools
formed. But as the rains continue the streams begin to flow in certain
parts of their course and eventually with every succeeding downpour
they become swollen torrent ; and in the case of gardens situated on
low-lying ground more or less temporory pools and swamps are formed.
At the height of the rains many of the torrents show no anopheles
larvæ ; but these are to be found in small collections of water of a
temporary nature that occur in the grass and jungle, or even in little
streams and drains which run intermittently and for the briefest period.
After the cessation of the rains during the months of September,
throughout October, and to a less extent during November and Decem-
ber, the streams feel by springs and the general soakage from their beds
become throughout most of their course stocked with the larvæ of ano-
pheles. By the end of December and the beginning of January the small-
er streams a,re dry or show only occasional small pools here and there,
or perhaps a few trickling springs, the condition we have described re-
sults, and for considerable distances there are no anopheles larvæ to
be found anywhere.
SPECIES OF ANOPHELES.
The common species of anopheles are M. lisloni, N. theobaldi and
P. rossi. The last species is fairly abundant in some places where
suitable breeding places occur; but it is not nearly so conspicuous
in the Duars as in many parts of India. M. barbirost ris is
found in great abundance in a few places ; but is not widespread,
or common in the district. N. fuliginosis and A. elegans also occur,
but not to any groat extent. A. sinensis is exceedingly common at
Jalpaiguri town, but rare in the Duars. M. Gulicjacies, the common
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malarial carrier of the Punjab, is also rare. N. stephensi, a common
Indian species, has never been found by us in the Duars.
Myzomyia listoni.—This is the most important species present,
and the one most frequently met with in dwellings. Its larva) are
especially abundant in running water, especially in the little boulder-
strewn streams where water continues to trickle for some time after
the cessation of the rains. They are found congregated in the shelter
of boulders, or lying in little pools and nooks at the odges of the bank,
and in the largest numbers where a few blades of grass project into
the water. They may be found also along the edges of streams
of considerable volume, even where there is no grassy or weedy growth
to shelter them, in quiet portions where, the current is broken by the
presence of large boulders. Very often they occur in large numbers
among the pebbles where the water is in such small amounts that it
cannot be dipped out until a small pool has been formed by the re-
moval of a few stones.
The adults can travel considerable distances and can rise several
hundred feet. High bluffs overlooking swampy country are often
infested with this species. They can exist through many months of
drought and may bo found when it is difficult to determine the breed-
ing places from which they have originated.
Nyssorhynchus theobaldi.—Like M. listoni this species is also a
stream-breeder, but its larvæ are found most frequently in the small
pools left during the drying up of the stream bods after the rains.
Like the larvæ of M. lisioni its larvæ, especially the larger ones, may,
when disturbed, sink to the bottom of the water and remain there
for long periods. We have frequently obtained thirty or more speci-
mens from a small pool a foot or so square by stirring up the bottom
and then waiting patiently for them to appear ; in such cases an ordi-
nary cursory examination might have led us to conclude that no
larvæ were present.
The adult is a strong flier and may be found in dwellings far
from its breeding places.
P seudomyzomia rossi.—This species breeds in the Duars in buffalo
Wallows, rice-fields, and small surface pools on roads and in lines.
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The adults exhibit considerable powers of passing through long
periods of drought.
Mysorhynchus barbirostris.—Is found breeding in grassy pools
and drains. In one case the larvæ of this species were seen in pro-
fusion in some foul water in a tea-house drain along with the larvæ
of P. rossi.
The adults do not appear to fly to any great distance, as will
be seen in the section on flight. The adults also disappear very quick-
ly after the drying up of their breeding places.
Nyssorhynchus fuliginosus.—Is found in some parts of the district
where there are larger pools of weed-covered water, but never in very
large numbers.
FLIGHT OF ANOPHELES.
Very often in the Duars we have found anopheles in consider-
able numbers in spite of the fact that the nearest breeding places
were a considerable distance away. Houses and lines on high bluffs,
for example, are almost invariably infested with anopheles, though
breeding places in such cases are nearly always several hundred
yards away. It seems certain that M. listoni and N. theobaldi habi-
tually traverse distances up to a quarter of a mile, and in the case of
N. theobaldi we have seen an instance where it seems certain that
adults were traversing nearly double this distance to reach a bunga-
low on a steep bluff.
It has often been taken for granted that the flight of anopheles
is a " random " one, but all evidence is in favour of its being purpos-
ive. That anopheles exercise very intelligent action in attempt-
ing to gain an entrance to rooms and mosquito-nets is very evident to
one who notes their behaviour when frustrated ; and their attrac-
tion by light often in very large numbers has been demonstrated
by us on several occasions. It is not at all surprising then that they
should direct their flight purposely towards light and sounds in a
bungalow, line, or bazaar, rather than be dependent on random