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Comparision of the tables showing the spleen index of wards ana sections,
shows how the pooling of figures may obscure the real condition of things. Thus
in the first table Ward 0. appears far less affected than A. and B., but reference
to the second table shows that portions of 0. Ward are really more affected
than parts of A. and B. Wards. This matter is exceedingly important as
it shows how closely the incidence of malaria is related to local conditions. If
we follow a line drawn across the island from east to west, cutting through in
succession Mandvi, Chakla, Market and Dhobi Talao Sections, we find—
(1) Mandvi severely affected with malaria with a spleen index of 37.8
per cent.,
(2) Chakla less so with a spleen index of 11.3 per cent.,
(3) Market more severely affected than Chakla with a spleen index of
14.3 per cent., and
(4) Dhobi Talao at the extreme west and separate from Mandvi by
two-thirds of a mile of streets and houses with a spleen index of 18.8
per cent. higher than either Market or Chakla Sections.
These observations point to the existence of a source of malarial infection
in the west of the island distinct from that responsible for the disease in Mandvi,
and investigation has shown this idea to be well found.
70. The areas most severely affected by malaria are Esplanade, North Port
and Mandvi Sections, These sections immediately adjoin the enclosure of the
New Dock Works and at first sight it might appear that proximity to the work
in progress there was the sole cause of their being severely affected by malaria.
But more detailed enquiry shows that although this explanation holds good in
regard to Mandvi and Esplanade Sections it is not equally so of North Fort.
In the first detailed spleen census of the Fort in 1909, 48.7 per cent. of children
living between Frere Road and the New Pock showed enlarged spleen, 27.8
per cent. of those living between Mint Road and "Frere Road, 35.5 per cent. of
those living east of Parsi Bazar Street and 42.8 per cent. of those living west of
Parsi Bazar Street. And the second spleen census in 1910 shows that if we follow
a line drawn diagonally through North Fort Section, from Port Street on the
extreme east to the corner of Church Gate Street and Hornby Road on the
west, we find, first an area near the Dock Works with a spleen index of 35.4
per cent., then west of this an area with a lower spleen index of 21 per cent.,
then further to the west another area with a spleen index of 35.6 per cent. and in
extreme west of the section farthest removed from the Dock Works an area with
a spleen index of 42.5 per cent. We have then in the North Fort a portion that
has been adversely affected by proximity to the New Dock Works and over and
above this another and much larger area lying to the west which is seriously
affected by malaria owing to some other cause. This latter cause is of
a similar nature to that giving rise to a serious amount of malaria in Dhobi
Talao Section, namely, the existence of hundreds of private house-wells breeding
malaria-carrying mosquitoes.
71. One of the most interesting and important facts brought out by the
spleen census is the comparative freedom of the whole of the north of the island
from any serious amount of malaria. It has been supposed for hundreds of years
that the ill-drained, low-lying areas in the Centre and North of Bombay, were
more malarious than the older portions of the City on the higher land to the south.
But it is a significant fact that among 6,132 children living in the undrained
portion of the island only 60 or 09 per cent. showed splenic enlargement,
whereas among 46,404 living in the drained portion 3,743 or nearly 8 per cent.
have enlarged spleen. It must be pointed out however that the apparent
relation of malaria to drainage is an accident, due to the fact that breeding
places favoured by the chief malaria-carrying anopheles of Bombay happen to be
present in the drained area and -absent in the undrained one. This mosquito
Neocellia stephensi does not breed in the foul water of house and street drains
and sewers, so that the existence of drains is not responsible for the presence
of malaria.
B 136—8