NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
72
suffered from no less than four great epidemics as well as a number of less severe ones.
Still further eastwards over the Central Epidemic Area we again have records of
three or four great epidemics. In the Southern Epidemic Area about Delhi there
is a falling off in the number of epidemics, only two major epidemics having pre-
viously affected this tract. If we continue further eastwards into the United Pro-
vinces we find, as we have already noted, that in 1908 this Province suffered severely.
But we shall find now that epidemics of great magnitude occur with nothing like
the frequency they do in let us say the Northern Epidemic Area in the Punjab.
In fact no epidemic of similar magnitude to that of 1908 appears to have been
recorded in the United Provinces.
We may remember also that even this epidemic affected only the western half
of the United Provinces. If we refer to the records of rainfall, we find that here
the explanation of the relative infrequency of epidemics cannot be due to lack of
rain, and in 1908 the eastern portion which was unaffected received not only more
rain than the western portions but an even greater excess over the normal (vide
maps comparing rainfall and fever given in the report of the Sanitary
C o m m i s s i o n e r w i t h t h e G o v e r n m e n t o f I n d i a , 1 9 0 8 ) .
Again if we map out roughly, by means of information given in the Gazetteers,
the relative areas under cultivation for wheat and rice respectively, we find a very
curious relation to epidemic prevalence. The rice land, which one might expect to
be the more malarious, marks on the contrary the limit at which epidemic condi-
tions cease. If we look for the reason why rice is cultivated instead of wheat, we
find that the limit of rice cultivation follows roughly the line of about 30 inches
average rainfall and an isotherm of increased average temperature, both condi-
tions we might reasonably expect to favour malaria.
At this stage we may well ask ourselves whether this liability of the Punjab to
epidemic malaria is not simply due to the fact that its inhabitants are less protec-
ted by immunity than are those of some other areas. If so we should certainly
expect areas in the Punjab normally with a high endemic prevalence to show during
epidemic times relatively less effect than more healthy areas. But at Amritsar the
portions of the city worst affected by epidemic mortality were those we have reason
to believe are permanently most subject to endemic malaria. At Delhi the same
relation holds good, Wards most affected in the epidemic are normally the most
malarious. These being cities it is possible that this selection by epidemic mala-
ria of the localities most affected by endemic malaria is due to the protection
enjoyed by the inhabitants of the central portions of the city. But in exactly the
same way we find in the Gherinda and Amritsar thanas the epidemic conditions
attacking not the least but the most malarious villages. The low-lying swampy
villages like Mahawa and Gumtala do not escape, but are the most severely
affected.
73
In Bhera thana it is those villages nearest the river which suffer most. In
Shahpur thana the villages where the conditions are most suitable for endemic
malaria and on the whole the villages which show the highest spleen rate are the
most affected by epidemic mortality. In Gujrat the same relation is seen ; the
affected villages are the most low-lying and have the highest spleen rates.
The form of epidemic malaira we are discussing would then appear to be not
the antithesis so much as the outcome of endemic intensity. But a closer scrutiny
of observations shows that in reality the two conditions are not interdependent,
though it would seem that on the whole villages in which the conditions favour
endemic malaria are more exposed to epidemic conditions.
This want of accurate relation will be evident from the following instances
described more in detail in previous chapters—
Villages.
Spleen rate.
Epidemic figure
October 1908.
Nathowala
.
.
. .
.
.
.
.
.
40
1
Kandan .
.
.
.
.
.
.
.
.
.
53
30
Akilshaw .
.
.
.
.
.
.
.
.
.
6 6
3
Dera Ali Tragger
.
.
.
.
.
.
.
.
67
9
Atari
.
.
.
.
.
. .
.
.
.
81
5
Shadiwal .
.
.
.
.
.
.
.
.
.
42
25
Kuthala .
.
.
.
.
.
.
.
.
.
75
27
What the condition of the spleen rate is in the rice growing portions of the
United Provinces I do not know. But in the western portions of the Punjab,
which we have seen are beyond the limit of normal epidemic prevalence, there is
no lack of endemic malaria. Multan I have frequently heard referred to by
medical officers as being a place in which enlargement of the spleen was quite
common, and Captain Brown, I.M.S., who sends me the result of the examination
of 273 children at Dera Ismail Khan, finds the spleen rate in this place to be 75
per cent.
The amount of endemic malaria roughly speaking depends upon one set of
conditions, that of epidemic malaria upon another. Very largely for these reasons
I have insisted on the relative independence of the two conditions. The essential
similarity of the nature of epidemic and endemic malaria will be discussed later.
III.—EFFECT UPON THE POPULATION.
Perhaps for the time the most important thing for us to grasp is the effect of
the two kinds of malaria upon the population.
L
74
If we take the total death rate in the whole Punjab from non-epidemic fevers,
we shall find that in round figures it is about 30,000 per month. In a year we
should get 360,000 deaths from non-epidemic fevers, including such diseases as
tuberculosis and many others; in fact this number would practically represent
the residue of deaths from all causes after abstracting a certain number of deaths
recorded as plague, small-pox, dysentery, etc.
In 1908 an equal number of deaths occurred in two months from epidemic
malaria alone. In Gurgaon district, which normally loses from non-epidemic
diseases about 17,508 persons in the year, there occurred in the month of October
1908 no less than 15,740 deaths or nearly as many people as would have died in
a whole year from non-epidemic disease. Sialkot, which normally loses about
3,000 a month from non-epidemic disease, lost in October 1890 33,609 persons and
in October 1892 20,972. Gurdaspur, which normally loses about 2,000 a month,
lost in October 1890 11,976, in October 1892 18,921 and in October 1894 10,551
persons. Umballa, which normally loses about 1,500 a month, lost in October
1890 17,025 persons.
Causes such as famine are usually supposed to exert the greatest influence on
increase of population and this may possibly be the case even though the actual
deaths do not equal those due to epidemic malaria. But for actual mortality
(excepting plague) there is no other cause in the Punjab to approach that of the
disease we are discussing. We shall understand this better when we endeavour
to explain the causes underlying these epidemics.
75
PART III
DETERMINING CAUSES OF EPIDEMIC AUTUMNAL MALARIA.
CHAPTER X.
Anopheles of the Punjab.
In the first volume of Theobald's Manual of the Culicidæ published in 1901,
the only species of anopheles mentioned as having been recorded from the Punjab
is N. fuliginosus (Giles). In 1902 Stephens, Christophers and James record
rossi (Giles) and M. culicifacies (Giles) as the two common species at Mian Mir
near Lahore, whilst the same observers in the same locality obtained M. barbirostris
(Van der Wu1p), C. pulcherrima (Theobald) and N. stephensi (Liston), the latter
two species being then new to science. James also records from the neighbour-
hood of Lahore N. fuliginosus and N. maculatus (Theobald). A single specimen
sent by me from Lahore is recorded by Theobald as M. minutus (Theobald), whilst
another single specimen also sent by me still forms the only example of Theobald's
species M. leptomeres (Theobald). At Ferozepore, about sixty miles to the south
of Lahore, Adie1 records M. rossi, M culicifacies, N. fuliginosus, N. stephensi, C.
pulcherrima, turkhudi (Liston), M. sinensis (Wied.), M. barbirostris, N. jamesi
(Theobald), and N. maculipalpis (Giles). He also calls attention to a variety of
N. fuliginosus peculiar to the cold months.
Thomson 2 from Dehra Dun at the foot of the hills just outside the borders
of the Punjab to the east records the common species as M. rossi, M. culicifacies
and N. maculatus, whilst the following species also occur, A. lindesayi (Giles),
M. nigerrimus (James and Liston), N. fuliginosus, N. theobaldi (Giles), M.
christophersi (Theobald), N. maculpalpis (Giles), N. indica (Theobald) and C.
pulcherrima. This as we shall see represents both a plains and a hill fauna.
In the hills A. lindesayi is recorded by Giles as early as 1900. It occurs as
we have seen at Dehra Dun. It is also recorded from Baldoh and Simla
6,000 feet (James and Liston).
From Kangra Theobald records as taken by Dudgeon Neocellia dudgeoni (Theo-
bald), probably the same species as James's N. willmori (James). From Kashmir
are recorded N. willmori and M. turkhudi. From Quetta beyond the Suliman
range two new species of the genus Pyretophorus, P. nigrifasciatus (Theobald) and
P. nursei (Theobald) together with another species of Neocellia, N. intermedia
1 Adie, Mosquitoes and Malaria in Ferozepore. Indian Med. Gazette, January 1905.
2 Thomson, Mosquitoes and Malaria in Dehra Dun. Jour. Royal Army Med, Corps, May 1909.
L2
76
(Rothwell) have been taken by Major Nurse who also records from the same
district M. rossi and M. culicifacies.
M. rossi.—I have found during its season in profusion at Delhi in the extreme
south-east, at Umballa and Amritsar in the central portion of the submontane
tract, and at Gujrat and Bhera to the north-west. Taking into consideration
also Adie's observations at Ferozepore and the experience of some other observers,
there can be little doubt that this species is during its season the commonest ano-
pheles throughout at least the eastern half of the Punjab.
The common anopheles at Dera Ghazi Khan in September was, I am informed
by Major Perry, I.M.S., C. pulcherrima, whilst Captain H. C. Brown, I.M.S., also
speaks of this species as the commonest species at Dera Ismail Khan. It is
possible that towards the west, where the monsoon rainfall is only a few inches,
M. rossi does not flourish to the same extent as further east; but observations
are required on this matter.
M. culicifacies. —Though it never or very rarely occurs in such profusion as
M. rossi is a very common mosquito and is found not only widely distributed
throughout the Punjab but also at almost all times of the year. I have found M.
culicifacies abundant at Palwal, Delhi, Umballa, Ghagger, Beas, Ferozepore,
Amritsar and Atari. Captain Brown, I.M.S., states it is very common at Dera
Ismail Khan.
N.
fuliginosus. —I have found abundant at Delhi, Armitsar, Lahore, Gujrat
and Ferozepore. It is like the two preceding species common throughout most
of the Punjab.
N. stephensi. —I have taken at Delhi, Umballa, Beas, Amritsar, and Lahore.
At Delhi this species is found in enormous numbers in the wells of the city, several
hundred larvæ being brought up by a single cast of the net. Its larvæ also swarm
in pools in the river bed of the Jumna and elsewhere. As noted by Dr. Bentley
in the case of Bombay the adults which hatch out from larvæ taken in the wells
are small. Specimens bred from open pools are so much larger that it is difficult
at first to believe that they can be the same species. But I have not been able to
note any marked differences other than in size. Adults hatched out from nymphs
taken on the river bed at Beas in February were small like those from the wells at
Delhi. At Amritsar the species is chiefly found in pools. It occurs also in wells
about the outskirts of the city but not as at Delhi in large numbers.
C. pulcherrima —Which at the time of its discovery seemed to be almost
peculiar to Lahore is evidently a common Punjab species. I have found it
sparingly at Delhi, Beas, Amritsar, Atari and Lahore.
M. barbirostris. —I have taken at Atari, Amritsar and at Delhi. It is found
in large open wells, but as a rule single larvæ only are captured. Colonel Adie,
77
I.M.S., tells me he has had the same difficulty in finding more than a few isolated
specimens at Ferozepore.
M. nigerrimus (James and Liston).—I have found rather more frequently
than M. barbriostris but never in large numbers. As already noted a specimen of
this species sent from Lahore was termed by Theobald M. minutus, and if this name
is to be used the specimens taken recently by me at Delhi and Amritsar would be
M. minutus as they agree with Theobald's description of this species. The differ-
ences, however, between M. minutus and M. vanus (Walker) are extremely small,
the only differences noted by Theobald being that the two wing spots in the first
species are white while in the second they are yellowish. Again the type speci-
men of M. nigerrimus (Giles) according to Theobald has the tips of the palpi
black, otherwise it resembles M. vanus. Size in the case of mosquitoes depends
very largely upon conditions under which the larvæ has lived and has but little
value as a specific character, also the name "minutus," though it may be ap-
propriate to the particular specimen sent home, is very out of place as applied
to the species under discussion which is noticeable among other anopheles of
the Punjab for its large size. The name M. nigerrimus (James and Liston) seems
to avoid these difficulties.1 The M. nigerrimus (Giles) with the black tipped
palpi I have not encountered.
M. turkhudi—Is a species not often taken and about whose habits not much
is known. I have found it in the bed of the Ghagger where this river first leaves
the foot hills (Siwaliks) for the plains, in the bed of th e Jumna at Delhi, and in large
numbers in the bed of the Beas. It seems indeed almost restricted to the beds of
rivers, for out of many thousands of larvæ obtained during February nnd March
from pools, jheels and else where this species was not represented, though a bund ant
at this time in the river beds. It is found not only in pools but is very fond of
places where water is oozing in a layer from the sand, especially if the sand has
become covered with the growth of alga. Under such circumstances one can
understand that the larvae do not require the palmate hairs, which in this species
are rudimentary. M. turkhudi is a very large mosquito and its larvæ especially
are noticeable on account of their great size and their stoutness when full grown.
Curiously enough this species was also found near the origin of a hill stream
at a height of between 4,000—5,000 feet near Kasauli. Finding it in this situation
I suspected that the specimens might be P. nigrifasciatus, but the scale structure
was identical with that seen in specimens of M. turkhudi from the plains.
A. lindesayi .—I have found in large numbers in the streams about Kalka at
.a height of 1,500—3,000 feet and at Pathankot. It is evidently a common hill
species.
1 Vide the new edition of James and Liston's Anopheles of India.
Neocellia willmori occurs in profusion both at Kalka and also near Kasauli at a
height of 4,000—5,000 feet. It is also to be found in the torrent beds at the foot o
the Kalka hills as far down as Chandigahr; but at Ghagger where the river bed has
become sandy I no longer found this species. N. willmori is equally common at.
the foot of the hills at Pathankot about 100 miles to the north -west of Kalka.
A single specimen of this species is stated by Theobald to have been sent by me
from Lahore. It is probably one of the commonest hill species and may possibly
be sometimes found at some little distance from them.
N. maculatus.—I have found abundantly at Pathankot. James and Liston
record this species from Lahore in March and April.
N. maculipalpis.—I have obtained in small numbers at Chandigahr below
Kalka and fairly abundantly at Pathankot. Adie records it as rare at Feroze-
pore.
N. indica .—I have taken at Chandigahr in considerable numbers along with
N. willmori.
Roughly speaking on the plains M. rossi, M. culicifacies, N. fuliginosus , C.
pulcherrima and N. stephensi are common species everywhere, whilst M. barbirosrtis ,
N. nigerrimus are generally found if systematic search be made, and M. turkhudi
if the pools in the bed of a large river are examined. The species M. maculatus,
M. willmori and M. maculipalpis are rare on the plains.
On the hills it is evident we have a very distinct fauna. A peculiar feature
is the number of speckled species closely resembling one another. Thus N. will-
mori, N. indica, N. maculatus, N. maculipalpis, N. theobaldi all very closely
resemble one another in their general appearance and are all found in small stony
streams among and at the foot of mountains. The dominance of the genus
Neocellia is also worthy of remarks.
The species one might have expected to find in the streams at th e foot of the
hills, namely M. listoni, appears to be rare, a circumstance the more noteworthy
as at the foot of the eastern Himalayas it is the commonest stream breeding
species.
The large number of species found and especially the large number of common
anopheles to be found at any one place in the Punjab is very striking
II.—SEASONAL PREVALENCE OF ANOPHELES.
During the cold weather when the night temperature may reach as low as 50°F.,
the larvæ of anopheles are not found in open pools but occur only in permanent
waters containing much aquatic vegetation; even in this situation larvæ are
scanty during December and January.
The first to note the species found under these circumstances and accurately
to follow the course of events during the winter was James. He notes that the
79
number of adult insects in the houses decrease during November, and that the
.species M. rossi completely disappear, neither adults nor larva being found after
the end of November. In the case of M. fuliginosus and C. pulcherrima on the
contrary adults were to be caught in reduced numbers in suitable places through-
out the winter and these species continue to lay their eggs and to go through
their metamorpho:es as usual. M. culicifacies was found to pass the winter in
the larval stage in which form it appeared to hibernate, the larvæ being sluggish in
their movements and growing very slowly if at all.
At Ferozepore Adie notes that N. fuliginosus is found throughout the year and
M. culicilacies very nearly so. M. rossi does not appear until July and disappears
by December. M. culicifacies is common from about the first of May and disap-
pears about the end of December. N. stephensi comes in about May and dis-
appears about the middle of November. The common species as a whole are most
numerous in September.
My own observations on seasonal prevalence have been made chiefly at
Amritsar, but they have been supplemented by less complete observations else-
where.
During the winter months N. fuliginosus was found breeding in large weedy
tanks to the north of the city, also in similar positions in the surrounding country.
Along with this species but in much smaller numbers was found C. pulcherrima.
In a large tract to the south of th e city, where there were no large permanent sheets
but numerous pits and pools containing little or no weed, no anopheles larvæ were
found breeding. The larvæ of M. culicifacies were first found at Amritsar in March,
but the species was breeding in profusion in February at Atari, 15 miles away, where
there were some very extensive and suitable breeding places. The species was
also found breeding at Beas and in the bed of the Ghagger at this time. N.
stephensi was first found in small numbers at Amritsar towards the end of February,
but this species was breeding in immense numbers in the wells and elsewhere at
Delhi at this time and was in fact the commonest species found there. N .
stephensi was also found in considerable numbers at Beas. At Atari in February
not a single specimen was found after much search. But the species was abund-
ant in March both at Amritsar and at Atari. At Ralka in February N. willmori
and A. lindesayi were both abundant in pools in the stream beds, and at Chandi-
gahr a few specimens of N. maculipalpis and of N. turlehudi were found.
By March the weather has become considerably warmer. At this time, adults
of N. fuliginosus, C. pulcherrima, M. culicifacies and N. stephensi were found quite
commonly and their larvæ occurred in profusion in almost every suitable situation.
But open pools free from weeds were still free from larvæ.
With the increasing warmth of April a still further increase of the spring species
-took place and in parts of Amritsar as many as a hundred adult N. fuliginosus could
80
sometimes be caught in a single suitable shed. Along with these there were
always a smaller number of C. pulcherrima, M. culicifacies and N. stephensi. In
the south portion of Amritsar (Hakiman), though it is one of the most malarious
portions of the city, anopheles were not so numerous, the reason evidently being.
that there were no suitable sheets of water in the neighbourhood. At Delhi also
in this month, though larvæ were found in profusion in the river bed and in parts
of the Civil Station, adults were caught with difficulty even in the outlying
portions of the city.
In the villages the conditions vary. In the drier ones a few anopheles only,
usually N. fuliginosus, N. stephensi and M. culicifacies, are to be caught; in those
villages which have large sheets of water near them almost all the species mentioned.
abound.
Up to April the increasing temperature has evidently favoured the propaga-
tion of the genus, but its continuation in the absence of rain by causing a progressive.
desiccation of breeding places now begins to act in a hostile manner. At this
time it is no uncommon thing to find swarms of larvæ, even those of N. fuliginosus,
in small almost dried up and very foul pools.
During June the few pools left are as a rule very unsuitable for breeding, and
not infrequently it may be difficult to find anopheles larvae in any particular neigh-
bourhood. Adult anopheles are also reduced in number. At Hakiman, after an
unusually dry summer (1910), only three specimens of anopheles were caught after
searching for some time. At Gurba Singh, where six weeks previously hundreds-
were to be caught, only seven were found in a search at this time. All were ex-
tremely small specimens, scarcely half the size of those found at more favourable
times.
Under such conditions the monsoon breaks and there is thenceforth a remark-
able change; for within a few weeks of the first fall of rain anopheles are again
found breeding in the utmost profusion everywhere.
So long as rain continues at short intervals these conditions are maintained,
with the result that there is an enormous and progressive increase in the numbers
of anopheles which far exceeds the increase of the spring; and instead of larvæ
being chiefly confined to large collections of water, such as tanks and sluggish weed
grown channels, they are now found in every situation where water remains any
length of time.
The species which come into prominence at the time of this enormous and
phenomenal increase of anopheles connected with the monsoon in the Punjab are
M. rossi and M. culicifacies. N. fuliginosus, the common mosquito of the spring,.
is now comparatively rare.
In 1909 M. rossi was not found at Amritsar until the end. of June. Yet during
the spring of 1910 I had occasion to breed out many thousands of larvæ caught.