NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
58
people newly arrived from the same district shewed that none of them had
splenic enlargement or other sign of malaria, a fact which supported his state-
ment regarding the absence of malaria in his village.
131. The only conclusion that can he arrived at regarding the origin of
the epidemic of 1908 is that, the existence of unrecognized centres of malarial
infection in various parts of the City and a gradual and unsuspected increase of
malaria in association with these centres was the prime cause of the outbreak
and the determining factor was a combination of climatic, economic and other
conditions favourable to the spread of malaria. Where these conditions could
act with greatest effect, i. e., in the area around the new dock-works and among
the coolie labourers encamped there, they produced a more intense outbreak
than in other parts of the City.
132. In view of this conclusion the question naturally arises :—
(1) Could the 1907-1908 epidemic of malaria have been prevented ? and
(2) Is there a danger of other similar epidemics occurring in
the future ?
It is very doubtful if there could have been such an epidemic if there had been
no more malaria in the Fort, Dhobi Taláo and the southern portion of the
City generally than there is in the centre and the extreme north of the
island. If steps had been taken to thoroughly investigate the distribution
of malaria on the island and the means by which it was spread after Powell
had shewn the comparative frequency of the disease among the City Police in
1901 to 1903 there is little question that the conditions favouring an increase
of malaria would have been recognized ; and it is probable that, if it had been
realized in 1904 that the North Port was a focus of malaria, adequate
precautions would have been adopted in connexion with the new docks
at the outset.
As to the possible recurrence of epidemic malaria in Bombay, it may be
remarked that, now that the facts are known and the danger recognized, there
should be less chance of malaria being allowed to pass beyond control. But
unfortunately malaria is far from being controlled at present. The small
attempts that have been made to limit it have only served to mitigate the
disease to a slight extent, and though it has bean checked a little in some areas,
unless more radical measures are adopted and carried to a successful termina-
tion, the City will remain as liable to epidemic outbreaks of malaria in tie
future as it has been in the past.
60
the basis of the pay and allowance of subordinate constables, would amount to
between Rs. 3,800 to Rs. 4,000 per annum. But if we estimate it at 1 per
rupees per annum during the last ten years, we should have to put it at more
than double this.
This latter sum is probably nearer the mark as it allows for Hospital
expenditure. In 1908 Police hospital expenditure exceeded Rs. 15,000, of
which 25 per cent. may be put down at the proportionate cost of treating the
cases of fever, which form over half the total admissions. Broadly speaking
we may state therefore that fever causes a loss of about Rs. 7,500 ;or £500 per
annum to the police establishment of the City, of which loss more than one-
half is due to 1 per cent. loss of duty among the subordinate police. As 75
per cent. of the fever cases treated are malarial in nature, 75 per cent. of this loss
or lis. 5,625 (£375) may be put down to malaria.
Applying this data to the general population, we may estimate as
follows. The Census of 1906 showed 588,544 actual workers in the City. If
we take their average earnings at Rs. 20 per month they amount to a total of
Rs. 14,12,50,560 per annum; and if we estimate that 1 per cent. of this was
lost either by the worker in wages or by the employer in work paid for but not
done because of "fever" we get a sum of over 14,00,000 rupees. Of this sum
75 per cent. or Rs. 10,50,000 may be assumed to be lost on account of malaria.
This estimate takes no account of the 389,000 dependants in the City
supported by the actual workers, sickness among whom causes considerable loss
to the latter. Por this it would be necessary to add several lakhs of rupees, so
that it will be evident that an estimate of Rs. 12,00,000 or 13,00,000 as the
cost of malaria to the City is a very low one, and probably much under the
real amount.
137. The figure given above does not include loss of rent to landlords
caused by the abandonment of houses in malarious localities and the loss to
tenants who are forced to leave and perhaps pay two rents for a time ; it makes
no allowance for loss to private persons forced to go to considerable expenses
for medical attendance or perhaps compelled to resign their appointments and
leave the City in order to recover their health ; and it does not include the loss
occasioned by the disorganization and lessened efficiency of a business staff, a
considerable proportion of whom are from time to time disabled by sickness.
If these and other losses, occasioned to the citizens of Bombay
by malaria, could be totalled up, in all probability it would be found that
the sum of Rs. 1/4 to Rs. 1/8 per head of the population, which has been taken
as the estimate, represents only one-half or one-third of the amount paid away
without return each year by the citizens of Bombay because of the existence of
an easily preventable disease in their city.
62
of them, notably Culex fatigans and Nysso-myzomyia rossi, are met with in
every part of the Island and are present in many localities in such countless
numbers as to become a grave nuisance. In the dry season from October to
June Culex fatigans is by far the commonest mosquito, but after the onset of
the rains Nysso-myzomyia rossi is produced in enormous numbers, and in
August and September, Stegomyiœ, notably Stegomyia sugens, Stegomyia
scutellaris and Stegomyia calopus (fasciata) become unpleasantly numerous.
142. Among the different species of mosquitoes present in the Island the
following have been noticed :—
Culicines—
Culex fatigans.
„ t œne or r hy nc hus . concolor.
„ tigripes.
Stegomyia calopus or fasciata.
„
scutellaris.
„
sugens,
„
gubernatorius (Giles).
Desvoidea obturbans.
Mansonia uniformis (Giles).
There are also several other culicine species present, that
have not been identified.
Anophelines—
Nysso-myzomyia rossi.
Neocellia stephensi.
Myzorhynchus barbirostris.
Nyssorhynchus jamesi.
„
fuliginosus.
Myzomyia listoni.
„
culicifacies.
143. According to the modern classification the Anopheline fauna of the
Island may be divided into five groups or genera.
(1) Nysso-myzomyia represented by one species N. Rossi.
(2) Neocellia
„
„ „
,,
N. Stephensi.
(3) Myzorhynchus
„
„ „
„
M. Barbirostris.
(4) Nyssorhynchus
„
„ two .,
N. Jamesi.
N. Fuliginosus.
(5) Myzomyia
„ two
„
M. Listoni.
M. Culicifacies.
James and Liston in the 1st edition of their monograph on the Indian
Anophelines also mention Nysso-myzomyia punctulata, Pyretophorus jeyporiensis
und Nyssorhynchus theobaldi as having been found in Bombay ; but these species
have not been met with during the course of the present enquiry.
144. The general character of the above groups and a description of the
different species present in Bombay is given below :—
NYSSO-MYZOMYIA.
Generic characters.
Abdomen.—Dorsal and ventral surfaces of the last one or two segments
carry scales as in the genus Nyssorhynchus.
Thorax.—With long narrow sharp-pointed scales as in the genus Myzomyia
and with some broader short scales.
Key to Larvæ of Bombay Anopheles Mosquitoes.
(1) Diagram of Anopheles larva showing frontal hairs F. H., which must not be
confused with feeding brushes F. B , also palmate hairs or fans P. H., a pair
of which is usually present on most of the abdominal segments.
(2) Complete palmate hair or fan from larva of N.-M. rossi.
(3) Single leaflet from palmate hair or fan of N.-M. rossi.
(4)
"
"
"
"
"
"
"
"
N. stephensi.
(5)
"
"
"
"
"
"
"
"
M. barbirostris.
(6)
"
"
"
"
"
"
"
"
N. jamesi and N. fuliginosus.
(7)
"
"
"
"
"
"
"
"
M. listoni and M. culicifacies.
Note.—Palmate hairs are present on the thorax of both M. listoni and M. culicifacies.
(8) Frontal or clypeal hairs of larva of N.-M. rossi.
(9)
"
"
"
"
"
"
"
N. stephensi.
(10)
"
"
"
"
"
"
"
M. barbirostris.
(11)
"
"
"
"
"
"
"
N. jamesi and N. fuliginosus.
(12)
"
"
"
"
"
"
"
M. listoni and M. culicifacies.
(13) Special branched hair on inner side of antennæ of M. barbirostris.
Note.—The branching of the frontal hairs of N. stephensi and M. listoni is so fine that it requires a 1/6th in. or
higher power objective to see it.
This plate was originally prepared to illustrate a paper on the Natu al History of Bombay Malaria, which
appeared in the Journal of the Bombay Natural History Society. It has been reproduced by permission.
64
Larval characters.—The frontal hairs of the clypeus of the larva are very
slightly branched, the branching being sometimes so fine as to require a
one-sixth objective or higher power to define it. The palmate hairs are
present on the first to the seventh abdominal segments ; the leaflets are usually
pigmented and broken-looking at the shoulder and the terminal filament is
comparatively short.
Ovum.—The ova are boat-shaped, but the upper surface is considerably
contracted owing to the striated scallop-shell shaped floats which almost meet in
the centre.
146.
MYZORHYNCHUS.
Generic characters.
Abdomen.—The dorsal surface with hairs only. The ventral surface with
a tuft of scales projecting vertically downwards from the apex of the seventh
segment in the mid line.
Thoras.—With sharp pointed very narrow, curved scales as in the genus
Myzomyia.
Prothoracic lobes.—With a dense tuft of broad scales.
Upright forked cephalic scales.—Very broadly expending.
Wing scales.—Not characteristic.
MYZORHTNCHUS BARBIROSTRIS.
Adult characters.—This is a very large mosquito, easily recognized by its
deep blackish colour and thick unhanded palpi. Beyond a frontal tuft of
whitish hairs, and a few white scales on the occiput and on the wings the entire
mosquito is a deep brown or black colour. The legs are dark brown with lighter
patches at the joints.
On examination with a miscroscope the head is seen to be covered with
black broadly expanding upright forked scales ; the thorax is covered with very
narrow curved hair-like brown or blackish scales ; and the abdomen has many
black hairs on its dorsal surface and possesses a tuft of black scales on its
ventral surface projecting downwards from the apex of the seventh segment in
the mid line. The scales forming the wing-fringe :are mostly black, but there is
a light area at the apex of the wings and another somewhat below at the apex
of the posterior branch of the fifth longitudinal vein.
Larval characters.—The larva are usually black or brown in colour, but
generally show two whitish bands on the upper surface of the abdomen. The
abdominal segments do not taper so rapidly as in the larva of many other
species and in young larvae the absence of tapering is so marked, as to give them
almost the appearance of equal width from thorax to tail. The irontal hairs
are peculiar, the inner hairs being usually long, simple and unbranched and
often crossed over one another at the tip. The external frontal hairs are thickly
branched and resemble cockades. The antennae bear a large branched hair on
their inner aspect.
Ovum.—The upper surface is very narrow, the floats do not touch the
margin of the upper surface. The lower surface is ornamented with polygonal
markings. Viewed laterally the pointed extremities of the upper surface are seen
to be turned up.
147.
NYSSORHYNCHUS.
Generic characters.
Abdomen.—The dorsal and ventral surfaces of the last three or two
segments carry scales which are not aggregated to form tufts.
Thorax.—With short, broad true scales.
Protheracic lobes.—Without a tuft of scales.
Upright forked cephalic scales.—Of the usual broadly expending type.
Wing scales.—Not characteristic.
68
The following table gives the results of the systematic examination of
3,228 stomachs of N. stephensi :—
Examination of Midgut for Zygotes.
Month.
1909.
July
August
September
October
November
December
1910.
January
February
March
April
May
June
July
August
September
October
November
December
1911.
January
February
March
Total ..
Number
dissected.
69
103
32
27
18
10
12
10
• • •
12
59
25
105
75
71
82
60
07
153
173
65
1,228
Number
infected.
11
12
3
3
• • •
..
•. •
..
..
• ••
12
14
10
9
5
5
6
1
..
91
Percentage
infected.
15.2
11.7
9.3
11.1
..
..
..
«••
..
..
11.4
18.6
14.0
10.9
8.3
7.4
3.9
0.5
7.4
Total zygotes
seen.
36
56
7
10
• • •
..
•••
..
..
..
..
..
108
158
52
35
6
29
15
;
2
!
..
The result of the examination of 1,217 salivary glands of Neocellia
stephensi is given below :—
Month.
1909.
July
August
September
October
November
December
..
1910.
January
February
March
April
May
June
July
August
September
October
November
December
1911.
January
February
March
Total ..
Number
dissected.
63
70
56
14
18
11
G
• • •
• • •
11
14
15
90
158
79
94
60
67
153
173
65
1,217
Number
infected.
1
4
2
1
..
..
..
..
..
'
..
9
5
4
2
1
1
..
..
30
Percentage
infected.
1.5
5.7
3.5
7.1
• • *
..
..
..
..
10.0
8.1
5.0
2.1
1.6
..
0.6
..
..
2.4
Key to Bombay Anopheles Mosquitoes.
No.
1. Head of Male Anopheles showing proboscis, spatulate palpi and plumose
antennæ. The banding of the palpi in the male anopheles is not
characteristic and affords no help to recognition of the species.
Nos. 2-6. Heads and Appendages of Female Anopheles showing characteristic
banding of palpi.
No. 2. N.-M. rossi.
No. 3. N. stephensi.
No. 4 M. barbirostris.
No. 5. N. jamesi, and N. fuliginosus.
No. 6. M. culicifacies, and M. listoni.
No. 7. Hind leg of M. rossi showing white bands at the joints.
No. 8. " " " N. stephensi showing speckling.
No. 9. " " " M. barbirostris unbanded almost completely black.
No. 10. " " " N. jamesi showing the white tips and the speckling. The legs
of N. fuliginosus are unspeckled but are white tipped.
No. 11. " " " M. listoni and M. culicifacies unbanded black or dark brown.
This plate was originally prepared to illustrate a paper on the Natural History of Bombay Malaria, which
appeared in the Journal of the Bombay Natural History Society. It is reproduced by permission.
No: V
No: VI
79
the previous formula and the resulting preparation when cold formed a thick
dark brown pasty mass. It was therefore heated up and diluted with three
parts of water, when it formed a dark brown treacle-like liquid smelling strongly
of carbolic acid. When a little of this solution was added to water it formed
a dirty white emulsion.
202. On being tested as a larvacide it was found to be very active,
destroying mosquito larvæ readily, even when used in very great dilution. The
original solution was made up so as to contain 25 per cent. of the crude carbolic
acid. Dilutions of this solution acted upon the larvæ of mosquitoes in the
following manner :—
Emulsion 1—1,000
( = to 1—4,000 of original carbolic acid).
Emulsion 1—5,000
(=to 1—20,000 of original carbolic acid).
Emulsion 1—10,000
( = to 1—40,000 of original carbolic acid).
Anopheles larvœ.
All died in 6
minutes.
All died in 15
minutes.
All died in 5
horn's.
Bulex larvœ.
All died in S
minutes,
All died in 20
minutes.
Almost no ac-
tion.
Stegomyia larvæ.
All died in 8
minutes.
All died in 20
minutes.
Almost no ac-
tion.
203. These results compare favourably those given in the following table :—
Larvacidal action of disinfectants.
McDougall's Saponified Cresols. 1—1,000
Do...1—5,000.
Phenyle
..1—1,000.
Do.
..1—5,000.
Jey's Fluid
..1-1,000.
Do.
..1—5,000.
Izal
. 1—500.
Do.
..1—1,000.
Do.
..1—5.000.
Anopheles larvœ.
All died in 7
minutes.
All died in 15
minutes.
All died in 12
minutes.
All died in
1/2 hour.
All died in 12
minutes.
All died in 25
minutes.
All died in 6
minutes.
All died in 9
minutes.
Almost no ac-
tion.
:
Culex larvæ.
All died in 8
minutes.
All died in 20
minutes.
All died in 15
minutes.
All died in 3/4
hour.
All died in 20
minutes.
All died in 28
minutes.
All died in 5
minutes.
All died in 9
minutes.
All died in 4 to
8 hours.
Stegomyia larvœ.
All died in 8
minutes.
All died in 20
minutes.
All died in 15
minutes.
All died in 3/4
hour.
All died in 20
minutes.
All died in 1/2
hour.
All died in 5
minutes.
All died in 9
minutes.
All died in 4 to
8 hours.
204. As crude carbolic acid can be obtained in bulk at a price of about
one rupee a gallon or less, an exceedingly cheap and efficient larvacide can be
prepared from it. In use it is found to have more action upon larvæ than
pupae, and nearly mature larvæ pupate rapidly on coming into contact with it,
so that it is a good plan to combine its use with that of kerosene or pesterine.
The original solution mixes with either kerosene or pesterine and very greatly
improves their toxic action and their powers of spreading quickly and evenly.
This is shown by the following experiments :—
80
Pesterine.
260 drops to 1 square yard of surface.
Mixture of Pesterine and Kerosene in
equal parts.
260 drops to 1 square yard of surface
Mixture of Pesterine and Carbolic Solu-
tion in equal parts.
260 drops to 1 square yard
Anopheles larvæ.
All died in 12
hours.
All died in 13/4
hours.
All died in 1/2
hour.
Culex larvæ.
Some die and
some survive.
All died in 3
hours.
All died in |
hour.
Stegomyia larvæ
Some die and
some survive.
All died in 3
hours.
All died in £
hour.
205. It may be remarked that the above experiments were conducted in
the dry weather. There is some ground for assuming that the effect of larva-
cides is greater upon mosquito larvæ hatched in the rainy season, as in a
previous scries of experiments carried out in the rains, larvæ died more quickly,
in the case of every larvacide used. It would appear from this that dry
weather larvæ are naturally more resistant to adverse influences than those
produced in the rainy season.
206. A further series of experiments were made with non-poisonous
larvacides—Malachite green and a new preparation "XeX"* prepared by a
Swiss firm and available in Bombay. Malachite green destroys mosquito
larvæ in dilutions as low as 1—25,000 in about 24 hours. Unfortunately the
brilliant bluish-green colour it gives to water is highly objectionable and water
treated with it does rot appear to retain its larvacidal properties very long.
207. XeX green has been experimented with in Italy and in Ceylon and
appears to have given satisfaction. It is especially useful in view of the fact
that animals can drink water containing it without ill effect. As supplied it is
in the form of a thick paste of a greenish brown colour. It mises fairly easily
with water, forming a dirty yellowish solution.
Experiments with larvæ in vitro gave the following results :—
XeX Green.
Solution 1—1,000
Solution 1-4,000
Auopheles larvæ.
All died in 20
minutes.
All-died in 23
hours.
Culex larvæ.
All died in 1/2 an
hour.
All died in 3 t <
4 hours.
Stegomyia larvœ.
All died in 3/4
hour.
All died in 3 to
4 hours.
A small pool containing mosquito larvæ was sprayed with a fairly strong
solution so as to form approximately a solution of a strength of about 1—4,000.
On the following day all the mosquito larvæ were dead. These experiments
appear to show that the new larvacide is likely to be of service especially where
toxic larvacides cannot be used. At present there is no data to show how long
water once treated remains toxic to mosquito larvæ.
* Samples were kindly supplied by Messrs. Volkart Brothers of Bombay.
No: VII
Govt. Photozinco: Office, Poona. 1911.
82
(2) Among infected people, climatic, social and economic and
other conditions, if favourable to man, tend to reduce the total number
of parasites, by increasing the powers of resistance of the persons concerned ;
whereas if unfavourable they may cause an increase in the number of
malarial parasites by lowering the powers of resistance of these persons.
Section 1.
214. It is necessary therefore to consider in some detail both the
conditions which may influence the number of malaria-carrying anopheles
and. those which may influence man's powers of resistance to malaria.
The conditions relating to anopheles, which may influence malaria, are :—
(1) Species of anopheles,
(2) Number of anopheles.
(3) Character of breeding places—
(i) Drainage.
(ii) Swamps.
(iii) Hice growing and Irrigation,
(4) Rainfall
(5) Other climatic conditions—
(i) Temperature.
(ii) Humidity.
Conditions which influence man in relation to malaria—
(1) Climate.
(2) Economic condition.
(3) Social condition.
(4) Overcrowding.
(5) Temporary aggregations of labour (soil disturbance).
(6) Education.
(7) Treatment.
(8) Migration.
215. Species of Anopheles.—We have already seen in the chapter on
mosquitoes that there are seven species of anopheles in Bombay which, from the
point of view of the spread of malaria, may be divided into three groups.
Known dangerous carriers of malaria.
(1) N. stephensi, M. listoni, M. culicifacies, and N. filiginosus.
Possible carriers of malaria.
(2) N. jamesi and M. barbirostris.
Non-carrier of malaria.
(3) Nysso-M. rossi.
If we compare a map showing the distribution of mosquitoes of group 1
with another map showing the distribution of malaria in Bombay, it becomes
apparent at once that there is a close relationship between the existence of
malaria among the population and the presence of the known carriers of the
disease. In the case of group 2 no such definite relation is apparent, and though
possibly N. jamesi may be concerned in the spread of malaria to some extent
the fact that this mosquito often occurs in association with either, N., stephensi
or M. culifacies or listoni obscures the relationship. It appears reasonably to
assume that M. barbirostris is not responsible for the spread of malaria in
Bombay because the places in which it occurs abundantly, i. e., Mahim and
other parts in the north of the island, show little evidence of infection. As
regards Nysso-M. rossi which is present in large numbers all over the island,
there is conclusive evidence that it does not carry malaria in Bombay and as
might be expected no relation can be traced between its presence and the
occurrence of malaria.
216. Number of dangerous Anopheles and Malaria in Bombay.—Broadly
speaking a definite relationship can be traced between the amount of malaria
present in different localities and the number of dangerous anopheles present
there as judged by the findings of larvæ and the occurrence of breeding places.
In Esplanade and parts of the North Fort where very large numbers of breeding
No: VIII.