It is
8 feet.
unlikely
that
a
variation of 8'
?
would with the water-level 30' down even have no effect, and one of a few inches with the level 8' down a considerable effect, on the ?
GROUND WATER AND MALARIA The paper read by Surgn.-Capt. L. Rogers, at the Epidemiological Society, on Febru-
ary 18th, 1898, on "The Relation of Variations in the Level of the Ground Water to the Incidence and Seasonal Distribution of Malarial Fevers in India" is similar to the one he read
fever rate, were other factors the same. But the other factors were not the same. In June the temperature is uniformly hot and the moisture In
low.
very
September
the
temperature
is
and the moisture considerable.
very fluctuating In fact all the conditions
we
know favour the
in the
development of malaria are present then, and in they are absent or only first beginning. In certain parts of Scinde, where the water-level
Scientific Memoirs of the Arm}7 of India for 1897, and is based on the same evidence with the addition of a few facts gathered during his
is very low and its variations slight, there is variation in the incidence of fever not to be explained by changes in water-level. When
Assam tour of
fever is found to
before the Calcutta Medical Society
subject
in 1895 and to the
The effect
ing ing
one
on
the
published
dut}7. of meteorological conditions,
same
includ-
ground water, upon various diseases, includmalaria, has been studied very largely in
India, and everyone who has done any work at the subject agrees that, for the results to have any value, the observations must extend over very many years ; while to attribute the variations in disease incidence to any one factor, all the other factors must be equally carefully
observed,
and their influence allowed for
cluded before
or ex-
with any certainty, attribute the chief role to that one factor. In Dr.
Rogers' work,
one can,
however
vations carried
on
for
we
a
find that from obser-
few months in
one
year It is true the
conclusions are drawn. observations were continued the following year by his successor and a similar chart was obtain-
large
ed, but this Dr. Rogers unfortunately left behind When Dr. Rogers returns to India we he will hope publish this chart. Observations
in India.
conducted in
one
place
ten, however, would
for two years
not be
or
convincing
even
unless
confirmed by similar ones conducted over a long period in many places. We are far from wishing to argue that subsoil water-level lias no influence on the incidence of malaria, but
only
that the observations now recorded are too few to justify the dogmatic conclusions arrived at Dr.
In June
a rainfall of lO" in a rise of seven feet in the waterfortnight, material a not is change and has no effect level, In rate. September a fall of 5" of upon the fever rain in two days causes a rise of about a foot in the water-level, and is accompanied by a rise in the fever rate. In the former instance the water-
by
Rogers.
with
level,
was
a
30 feet
down,
and in the latter about
June
occur
during
a
low water-level
Dr. Rogers says?" The obvious explanation of these facts is that the cases which occur at the time of the year when the water-level is low
are
relapses from among those men who were attacked during the preceding season." Such reasoning would explain variation of fever-rate at any water-level.
Arguments adduced equally unconvincing
assumption
from kala-azar work
are
because based upon the that kala-azar is an epidemic com-
municable form of malarial fever, which we are prepared to admit unless the facts to be
not
mentioned
Dr.
tended
at another
are
by reading
more
report
oil
Rogers
in the paper he in-
Society on kala-azar published in his already published and
definite than those the disease
reviewed in these columns. The paper concludes with the following suggestion of a possible method of infection in malarial fevers, which its author says will
quainted
explain all the facts he is acIf malarial fever may be conbreathing in the malarial organisms,
with
:
"
tracted by why should they
not be also breathed out
again completed their work in the have only to pass back again into of the lungs, and they will be able to the alveoli more easily than they escape from these organs of the air-passages will entered, for the cilia have
they body ? They when
assist their exit. This simple theory seems to the elaborate me to be much more likely than is which theory largely based on an
mosquito
between such widely different constithe animal scale as the Plasmodium of tuents malar'ce and the jilaria sanguinis hominis,
analogy
while it is also, I think, more in consonance with the known facts as to the incidence and
May
1898.]
MORBID ANATOMY.
seasonal distribution of malarial fevers." say Dis. Mauson aud Ross to this ?
What
185
8 feet.
unlikely
that
a
variation of 8'
?
would with the water-level 30' down even have no effect, and one of a few inches with the level 8' down a considerable effect, on the ?
GROUND WATER AND MALARIA The paper read by Surgn.-Capt. L. Rogers, at the Epidemiological Society, on Febru-
ary 18th, 1898, on "The Relation of Variations in the Level of the Ground Water to the Incidence and Seasonal Distribution of Malarial Fevers in India" is similar to the one he read
fever rate, were other factors the same. But the other factors were not the same. In June the temperature is uniformly hot and the moisture In
low.
very
September
the
temperature
is
and the moisture considerable.
very fluctuating In fact all the conditions
we
know favour the
in the
development of malaria are present then, and in they are absent or only first beginning. In certain parts of Scinde, where the water-level
Scientific Memoirs of the Arm}7 of India for 1897, and is based on the same evidence with the addition of a few facts gathered during his
is very low and its variations slight, there is variation in the incidence of fever not to be explained by changes in water-level. When
Assam tour of
fever is found to
before the Calcutta Medical Society
subject
in 1895 and to the
The effect
ing ing
one
on
the
published
dut}7. of meteorological conditions,
same
includ-
ground water, upon various diseases, includmalaria, has been studied very largely in
India, and everyone who has done any work at the subject agrees that, for the results to have any value, the observations must extend over very many years ; while to attribute the variations in disease incidence to any one factor, all the other factors must be equally carefully
observed,
and their influence allowed for
cluded before
or ex-
with any certainty, attribute the chief role to that one factor. In Dr.
Rogers' work,
one can,
however
vations carried
on
for
we
a
find that from obser-
few months in
one
year It is true the
conclusions are drawn. observations were continued the following year by his successor and a similar chart was obtain-
large
ed, but this Dr. Rogers unfortunately left behind When Dr. Rogers returns to India we he will hope publish this chart. Observations
in India.
conducted in
one
place
ten, however, would
for two years
not be
or
convincing
even
unless
confirmed by similar ones conducted over a long period in many places. We are far from wishing to argue that subsoil water-level lias no influence on the incidence of malaria, but
only
that the observations now recorded are too few to justify the dogmatic conclusions arrived at Dr.
In June
a rainfall of lO" in a rise of seven feet in the waterfortnight, material a not is change and has no effect level, In rate. September a fall of 5" of upon the fever rain in two days causes a rise of about a foot in the water-level, and is accompanied by a rise in the fever rate. In the former instance the water-
by
Rogers.
with
level,
was
a
30 feet
down,
and in the latter about
June
occur
during
a
low water-level
Dr. Rogers says?" The obvious explanation of these facts is that the cases which occur at the time of the year when the water-level is low
are
relapses from among those men who were attacked during the preceding season." Such reasoning would explain variation of fever-rate at any water-level.
Arguments adduced equally unconvincing
assumption
from kala-azar work
are
because based upon the that kala-azar is an epidemic com-
municable form of malarial fever, which we are prepared to admit unless the facts to be
not
mentioned
Dr.
tended
at another
are
by reading
more
report
oil
Rogers
in the paper he in-
Society on kala-azar published in his already published and
definite than those the disease
reviewed in these columns. The paper concludes with the following suggestion of a possible method of infection in malarial fevers, which its author says will
quainted
explain all the facts he is acIf malarial fever may be conbreathing in the malarial organisms,
with
:
"
tracted by why should they
not be also breathed out
again completed their work in the have only to pass back again into of the lungs, and they will be able to the alveoli more easily than they escape from these organs of the air-passages will entered, for the cilia have
they body ? They when
assist their exit. This simple theory seems to the elaborate me to be much more likely than is which theory largely based on an
mosquito
between such widely different constithe animal scale as the Plasmodium of tuents malar'ce and the jilaria sanguinis hominis,
analogy
while it is also, I think, more in consonance with the known facts as to the incidence and
May
1898.]
MORBID ANATOMY.
seasonal distribution of malarial fevers." say Dis. Mauson aud Ross to this ?
What
185
