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throughout the whole year. In India it is easy to find almost every condition
of prevalence, so that whereas in Africa a very large proportion of the natives
have the opportunity of becoming relatively immune by repeated infections
during childhood, in India only those natives who have lived all their lives in
such places as the Duars enjoy an immunity.
This, of course, includes but a very small proportion of the whole Indian
community, and the fact that the average adult native of India enjoys no
immunity is shown by the certainty with which he contracts malarial fever
when exposed to infection.
It probably requires ten or twelve years of constant infection and reinfection
before an immunity is established, and it is possible also that, even then, the
relative immunity only applies to the variety of parasite with which the indivi-
dual has been infected.
The nature of the infection in native children .
The work done by Drs. Stephens and Christophers in Africa, on the infec-
tion of native children,* led them to the conclusion that the infection in such
cases was different from an ordinary attack of malaria in an adult, in that (I)
they did not observe any rise of temperature in the children, nor any of the
usual symptoms of malarial fever, and (2) although asexual forms of the
parasites were not uncommonly seen, the chief characteristic of the infections
appeared to them to consist in the presence of a large number of sexual forms
having characters differing from those of the sexual forms usually found incases
of malarial fever occurring among Europeans. They had no opportunity of fol-
lowing out the cycle of the parasites in a case over a period of 24 or 48 hours.
This subject has not been worked at in India by Drs. Stephens and
Christophers, but as it has always appeared to me that malaria must be one of
commonest causes of death among native children in India, I thought it would
be of advantage to study the question somewhat more closely, especially with
the object of ascertaining whether the health of the children is really much
affected by the presence of malaria parasites or not.†
Owing to difficulties which will be readily understood by any one who has
attempted to take temperatures or blood specimens in an Indian village, the
number of cases which I have examined is not large, but they are, I think,
sufficient to draw conclusions from. The cases which follow were taken without
selection from children who were playing about in the village, and presented, on
a casual examination, none of the ordinary symptoms of malarial fever.
Freedom from symptoms, indeed, as was pointed out by Drs. Stephens and
* "The Malarial Infection of Native Children, " by J. W. W. Stephens, M.D. Cantab., and S. R.
Christophers, M.B. Victoria, in the Reports to the Malaria Committee of the Royal Society. Third Series,
1900.
. † T h e s t a t e m e n t o f D r s . S t e p h e n s a n d C h r i s t o p h e r s o n t h i s p o i n t i s a s f o l l o w s : — “ I t m u s t b e u n d e r s t o o d
that in speaking of a case of malaria in children, we are referring only to the presence of parasites; the
children are perfectly well, and present none of the characteristic signs observed in Europeans affected with
malaria." (Loc. cit., page 4.)