The midland journal. (Rising Sun, Md.) 1885-1947, 1897-09-24
MEDICAL GEOGRAPHY.
Areas Of Disease Clearly Indicated
on the Map.
Portions of the Earth Where Certain
Diseases Prevail-Of Great Adj
vantage to Medical
Science.

1t is common knowledge that dis
eases have as rule their local habita-
tions. Some. like tropical animals and
plants, live only in the tropics; some.
like consumption, are gradually spread
ing over the whole earth; others, like
leprosy and smallpox, are gradually be-
coming limited in their distribution,
and may actually be tending toward
extinction. Again, there are regions
to which diseases have never reached.
On the SUBMITS of high mountain
ranges and in the circumpolar snow
fields the earth and air and water are
as barren of the microbes of disease as
they are of animal life.
In country like Britain, thickly pop
ulated for many centuries, and with
the freest circulation of population, it
cannot be doubted that every yard of
surface contains the gerps of the more
common diseases; and the native of
some newer land, brought over here.
falls victim to our plague-stricken
soil. By generations of a destructive
elimination we have become highly re-
sistant to our native diseases, just as
the Gold coast natives are less suscep-
tible than we are to their own local dis
eases. But we are not fully protected,
and cancer and consumption, two of
our common scourges, still take large
annual toll. 1t may be assumed that
both are due to microbe organisms, the
microbe of consumption being we'll
known, and that of cancer being as yet
only suspected. Probably no inhabit-
ant of Britain escapes infection by the
cancer organism; certainly none escape
infection by the microbe of tubercle.
Most of us, fortunately, resist the in
truders, and are unaffected by the dis
ease.
A strikingly interesting result be-
comes plain when the incidence of fatal
cases is plotted out on Il map. The
usual method is to color the districts
with different shades. according to
their rates Of mortality. Blue is chosen
for high mortalities, red for low NOR
talities, the deepest blue showing the
highest and the deepest red the lowest
rate. When two maps colored in this
compared. it is at once evident that the
incidence of the disease is not capri
cious; the shades do not form mean
ingless patchwork, but show at the first
glance strlingly regular distribu-
ton. The one map forms almost exact
ly complement of the other. The
deep blue of cancer high mortality CO.
1x,itb laaY, rod Of
ton low mortality. Where the con-
sumption mortality is highest that
from cancer is lowest, and. on the
whole, there is a similar inverse cor
respondence between intermediate
rates of mortality.
When the mortality maps are COM
pared with good physical map, it may
be seen that the structural features OF
the country are in direct relation to the
death rates. The deep blue of cancer
high mortality prevails in low-lying.
well-protected river valleys, where
fully formed rivers flow down to the
| sea between low banks, cutting their
way through beds of clay and recent al
luvial soil; in fact, where seasonal
floods are frequent and strong sea
winds rarely flush out the protected val
leys, there cancer prevails and finds its
fattest harvest. The lower courses of
the greater rivers from the Tweed to
the Thames and from the Stour to the
lamar. the rivers of the North Devon.
the Severn and the Dee are all thiclily
set with blue cancer patches. On the
other hand the lowest mortality groups
occur on high upland downs. along the
watersheds, and especially where
ridges of limestone rock rear them
selves around the surrounding country.
In the sheltered valleys where cancer
prevails, notwithstanding the damp
ness and periodical flooding the very
lowest mortality rates from consump-
tion occur. Inland from the low fore
shores and high above the protected val
leys. wherever strong sea winds pre-
vail. and along the lofty ridges like
that forming the backbone of Wales,
the bluesof consumption high mortality
is found. Not dampness, but exposure,
seems to be the exciting physical cause.
Although the contrast between con-
sumption and cancer is too striking to
be purely coincidence, it cannot be
said that enough is known to explain
it by ultimate causes. The therapeutic
value of exposure to constant supplies
of pure air is evident enough in all dis
eases that affect the general vitality of
the body. 1t is more than probable that
the low cancer mortality in the exposed
= ;e 10 ha l>af 10.
gienic conditions that prevail in them.
The pulse of life beats more slowly.
and every bodily and mental activity is
feebler on the sodden soil of the dull
valley where cancer rules. But we do
not know how cancer gets from patient
to patient. nor if its organism has be-
come purely parasitic on the bodies of
animals. No doubt all the microbes of
disease were at one time harmless veg
etables, living an idyllic life in the mud.
Some of them are still able to maintain
an existence outside the bodies of their
victims, and the relation of cancer to
clay soils and flooded districts suggests
that it may not yet have reached pure
ly parasitic stage. Other and more spe-
cialized microbes apparently have lost
their primitive capacity to live free
life. and their specialization is prepar-
ing the way for their extinction. If the
microbes die unless they reach quickly
another living host, isolation of infect
ed cases, carried out thoroughly, will
ultimately rid us of their existence
London Saturday Review.