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CHAPTER IV,
THE SPLEEN CENSUS.
The percentage of indigenous children showing enlargement of the
spleen, a condition rarely due in childhood to any other cause, has been found to
a most excellent means of judging of the extent to which Malaria prevails in a
community.
In working out the Malariology of an area sufficiently limited to be
dealt with completely, the taking of the Spleen Bate, as it is called, is only one
of a number of "means of study. But the Spleen Census by itself gives results so
accurate and so rapidly obtainable that when it is merely a case of finding out
whether a given tract of country is malarious or not, or of judging of the
relative malariousness of different parts of one, it is neither practicable nor
necessary to combine with it any other means of demonstrating the amount of
Malaria present. ,A Spleen Census among children has accordingly been used
as the best method of demonstrating the great variations which exist in the
extent to which the different parts of Salsette are affected by the disease.
The accompanying map of the island of Salsette shows the percentage
figure of the Spleen Rate marked in under the name of each town or village.
In order to show more graphically the wide differences that exist between
different places in respect of Malaria, different colours have been used. Figures
up to 10 per cent. have been entered in green ; those up to 25 in orange ; those
up to 50 in brown, and those above 50 in red.
It is an obvious possible use of this map to take its figures as a guide in
making out another map, showing the whole island marked out in patches of
colour, according to their relative malariousness or non-malariousness, in order
to assist those who have to judge of where to build and where not to build.
But the boundaries of such coloured areas would be very difficult to determine
in any reliable manner, and the more so in those very parts where Malaria, has
so thinned the population that the means of taking a representative Spleen
Census are absent. It is better not to attempt to make the figures show more
than they do show, and to trust to the general lessons they teach for guidance,
in areas where they do not give detailed information.
While the-Spleen Rate is not influenced by the severity or otherwise
of a particular Malaria Season to anything like the same extent as an Endemie
Index consisting of the percentage of children found to harbour the malarial
parasite in the blood, it is only to be expected that good and bad years
should make some difference in it. It is well at the outset to note, then,
that the year 1911, which is the one whose Malaria season would exercise the
greatest influence on the Spleen Bate taken in 1912 was a distinctly mild
fever year, as the season of 1912 promises to be also, so that the figures
certainly do not over-estimate the extent to which Malaria prevails in
Salsette.
The following table gives in alphabetical order the towns, villages and
hamlets in which the Spleen Census was taken. In the case of the villages
round Thána, it was taken by the writer in December 1911, in the course of an
investigation carried out in order to find out if any part of the environs of
Thána was sufficiently non-malarious to allow of .the building of residences for
district officers. Here the Spleens are not classified according to size. In the
case of the villages and towns of the rest of the island, in which the Spleen
Census was taken in October and November 1912, as part of the special
investigation which is the subject of this report, they are classified according to
the method recommended by the Central Malarial Committee. In all 7,156
children were examined :—
H 629—4