In one sense most diseases are preventable, if all the circumstances
which tend to spread them could be absolutely controlled by a single
wise authority, and if all the physiological laws would be obeyed by all
persons at all times. But as this happy condition is not in effect, we
have to reckon with various kinds of diseases, as well as the accidents
and injuries which come to us in health. The various diseases are
classified into general groups.
Endemic diseases are those which are constantly present in a community
because of certain unfavorable conditions, such as malaria in swampy
regions, rheumatism from bad climatic conditions, and diseases resulting
from unhealthy employments. Miasmic diseases are those due to conditions
of the soil, and comprise the various forms of intermittent fevers,
agues and the like. Infectious diseases, on the other hand, belong to
the people, and not to the place. They are communicated from one person
to another through the air, or by means of infected articles of
clothing, etc., and they attack the strong and healthy, no less than the
weak. Among such are smallpox, scarlet fever, measles, etc. Various
branches of infectious diseases are recognized in addition, as combining
some of the characteristics of the classes already named. For instance,
erysipelas and other blood poisons are generated with the body of the
individual who, so to speak, infects himself and may then infect others.
Typhoid, cholera and yellow fever are miasmic diseases, but they are
also capable of being carried by human intercourse, infected clothes,
polluted water, etc., within certain limits of space and time.
Hydrophobia, glanders and such diseases are communicated only by actual
contact of body. Rickets and scurvy are preventable, though not
communicable diseases, being direct results of mal-nutrition or
imperfect nourishment, and consequently are diseases of diet.
Bacteria are those minute organisms which under various names are the
active causes not only of diseases but of all putrefaction, fermentation
and like changes in dead organic matter. Like all living things they may
be killed, and on this is based the whole theory of disinfection. Some
are more hardy than others, under conditions which are frequently
supposed to be unfavorable to them. Merely to destroy an unpleasant odor
or to admit fresh air into a room does not mean to disinfect, and it is
necessary to understand this clearly in the effort to purify rooms in
the event of infection.
Contagion is communicated sometimes with the utmost ease, if the new
victim be in a receptive condition, and in the presence of any disease,
even the most simple, it is well to take every precaution. The mucous
surfaces are peculiarly ready to absorb infection of many kinds. Measles
is easily absorbed from pocket handkerchiefs, as are also scarlet fever,
whooping-cough and other diseases. By inhalation through the nostrils or
mouth, scarlet fever, measles, whooping-cough, mumps, diphtheria,
dysentery, cholera and even pneumonia and meningitis may be
communicated. By eating or drinking something which contains the germs
of cholera, typhoid, malaria, tuberculosis or consumption, diphtheria
and scarlet fever, these diseases are communicated.