33
The results found among Parsis and other classes in the north Port is
noted below :—
Parsis
Other Classes
Percentage,
Class No. 1.
61.3
70.2
Percentage,
Class No. 2.
14.1
18.5
Percentage,
Class No. 3
14.8
12.2
Percentage,
Class No. 4.
5.0
3.2
Percentage,
Class No, 5.
1.2
0.7
78. BLOOD EXAMINATION.—Although the spleen census gives most
valuable information regarding antecedent malaria and may be used as a measure
of malarial endemicity, the microscopio examination of the blood gives informa-
tion regarding the actual presence of infection, and the species of parasite, not
to be gained in any other way. Years ago Stephens and Christophers suggested,
as a measure of malarial endemicity, the use of an infection index arrived at
by the microscopical examination of the blood of young children. This
suggestion was based upon a consideration of the following facts.
In a
very malarious locality nearly all now comers usually contract malaria after
a short stay of days or weeks ; in a less malarious locality a smaller proportion
become infected in a given period; and in a place where malaria is only
mild, new comers may escape infection for months or even years. Therefore
the examination of new comers for the presence of malarial infection enables
the observer to arrive at a figure of value for comparative purposes ; and as
a rule young children are selected for the purposes of this examination
because they form a class of new comers more or less fixed in character and
available everywhere. But in Bombay, where a large proportion of the
population is formed of new arrivals and temporary residents, there are
many thousands of adults who are probably quite as susceptible to malarial
infection as young children ; and it has been found that the adult population
of malarious localities in the City is infected with malaria in much the same
proportion as the child population. During the present enquiry a large number
of blood films have been collected from both children and adults in different
parts of the City. As it is quite impossible to examine the blood of more than a
small proportion of the population in a City as large as Bombay, it was necessary
to adopt a system of" random sampling," when obtaining specimens for the
estimation of the parasite index. The method employed in the collection of
blood films during the investigation was as follows:—A locality, chosen indis-
criminately, was visited usually in the early morning. Conversation was
exchanged with some resident or passer-by until a crowd collected. After a
little persuasion, some one would consent to allow his finger to be pricked and
a blood film prepared, and it would soon become fashionable to follow suit.
Children coming forward or brought by their parents were rewarded with a
pice. In this way it was usually possible in the course of an hour to collect
50 or 60 blood films, specimens being taken from every one in the crowd who
appeared willing. Blood films were collected in this manner from over
\ill\00 localities in different parts of the City.
79. Parasite Index.—The parasite index of the different wards in the
City obtained by the examination of the blood of people from about 100
different localities is as follows :—
Tables of blood examination showing the amount
of street infection in each ward.
Ward.
Ward A. ...
B. ...
0
D. ...
,
E. ...
„
F. and G.
Total ...
Number
examined.
2,681
473
707
354
878
302
5,395
Number
infected.
943
65
196
19
33
11
1,267
Percentage
infected.
34.8
137
27.7
5.3
3.7
3.6
23.4
B 136—9