There are two grand divisions under which all contagious diseases may be
classed:--1. Those which spring from organized living beings, and from the
life in them, and which enter, as it were, into the life of those in whom
they reproduce themselves--such as small-pox and measles. These become so
domesticated with the habit and system, that they are rarely received
twice. 2. Those which spring from dead organized, or unorganized matter,
and which may be comprehended under the wide term _malaria_.
You may have passed a stagnant pond a hundred times without injury: you
happen to pass it again, in low spirits and chilled, precisely at the
moment of the explosion of the gas: the malaria strikes on the cutaneous or
veno-glandular system, and drives the blood from the surface; the shivering
fit comes on, till the musculo-arterial irritability re-acts, and then the
hot fit succeeds; and, unless bark or arsenic--particularly bark, because
it is a bitter as well as a tonic--be applied to strengthen the veno-
glandular, and to moderate the musculo-arterial, system, a man may have the
ague for thirty years together.
But if, instead of being exposed to the solitary malaria of a pond, a man,
travelling through the Pontine Marshes, permits his animal energies to
flag, and surrenders himself to the drowsiness which generally attacks him,
then blast upon blast strikes upon the cutaneous system, and passes through
it to the musculo-arterial, and so completely overpowers the latter that it
cannot re-act, and the man dies at once, instead of only catching an ague.
There are three factors of the operation of an epidemic or atmospheric
disease. The first and principal one is the predisposed state of the body;
secondly, the specific _virus_ in the atmosphere; and, thirdly, the
accidental circumstances of weather, locality, food, occupation, &c.
Against the second of these we are powerless: its nature, causes, and
sympathies are too subtle for our senses to find data to go upon. Against
the first, medicine may act profitably. Against the third, a wise and
sagacious medical police ought to be adopted; but, above all, let every man
act like a Christian, in all charity, and love, and brotherly kindness, and
sincere reliance on God's merciful providence.
Quarantine cannot keep out an atmospheric disease; but it can, and does
always, increase the predisposing causes of its reception.
_April_ 10. 1832.