Before beginning the consideration of the
individual diseases enumerated in the title, a
review of some of the things which relate to
them in common may prevent subsequent repetition.
The importance of this group of diseases
is realized when one remembers that
during the ten years ending in 1922, in a large
city such as Chicago, more than one person out
of every seven of the population suffered from
one of these diseases and one out of every 150
died from one of them. Combined these diseases
cause about one-fourth of the deaths
among children from one to ten years of age.
Not only are they responsible for abundant
deaths, but they also leave in those that recover
a legacy of permanent damage in the
heart, lungs, ears, eyes and other parts of the
body. Statistics show that more than one-fifth
of the cases of deaf-mutism follow scarlet
fever, measles and diphtheria. Chronic diseases
of the heart and of the kidneys may be
due to earlier attacks of scarlet fever.
The diseases here considered constitute an
important part of those which are known as
contagious. Contagious diseases are those
which are transmitted from one person to
others by direct or indirect contact. They are
sometimes also designated “communicable
diseases.”
CAUSES
Each of these diseases is caused by its own
peculiar germ. We may compare the germs
causing contagious diseases to seeds of plants.
Each variety of seed will produce only the sort
of plant from which it came. Each of these
diseases is due to the implantation of its own
peculiar germ in the body, and except in this
way the disease never occurs. Each case thus
originates from a previous case of the same
sort. The old idea that contagious diseases
are caused by sewer gas, bad air, disturbances
in the weather or similar things, is now known
to be untrue. The germs causing diphtheria,
scarlet fever and whooping cough and perhaps
measles have been isolated and studied. They
are all bacteria, which are very small vegetable
organisms. In order to be seen by the
human eye, they must be magnified about one
thousand times by a microscope.
As seeds must be placed in suitable soil if
they are to grow and produce plants, so disease
germs must find a suitable soil in the
body in order to cause disease.
IMMUNITY AND SUSCEPTIBILITY
If disease germs are received by a person
whose body acts as barren soil no disease results,
while if they reach a person whose body
furnishes suitable soil for growth, disease follows.
The former person is said to be immune
to the disease. The latter is spoken of as
susceptible. It is well known that few persons
ever have the same contagious disease twice.
One attack renders immune a person who was
susceptible. This explains why we have epidemics
of contagious diseases. During the
epidemic most of the persons in a community
who are susceptible contract the disease. At
the end of the epidemic most of the suitable
soil for the growth of the special germ has
been exhausted and the population of the community
has become immune to the disease.
This causes the epidemic to cease. Another
outbreak in the same community of the same
disease can only occur when susceptible individuals
have again accumulated, i. e., when
children have been born and reached a suitable
age. Epidemics of contagious diseases are
naturally confined largely to children who have
grown up after the last epidemic occurred, the
older members of the community having been
rendered immune by attack of the disease
earlier in life. In isolated situations where the
germs of contagious diseases are not often
introduced persons may reach adult age without
ever having been exposed to them. Such
adults may then become infected the same as
children. In the late world war large numbers
of young men from rural communities who had
never had the usual contagious diseases were
brought together in training camps, and thus
furnished fertile soil for many epidemic diseases.
In a study of over 30,000 native white
children in 14 localities in the United States
it was found that at 5 years of age 65% have
had measles, 48% whooping cough, 22% chicken
pox, 5% scarlet fever, and 3.5% diphtheria.
As age advanced the proportions increased
until at 15 years of age, 88% have had measles,
77.6% whooping cough, 51% chicken pox, 11.6%
scarlet fever, and 8.7% diphtheria. By young
adult age most persons have had these diseases
which are often spoken of as children’s
diseases, but some persons are affected later,
some adults at quite advanced age.
HOW NEW CASES ORIGINATE
The germs which cause these diseases are
given off and escape from the sick person in
various secretions and discharges. This includes
discharges from the throat, nose, ears
and eyes; pus from abscesses in the neck;
sputum or other excretions. The crusts from
the skin lesions of chicken pox contain the
germs of the disease, but the scales from the
skin in measles and scarlet fever do not usually
do so. The amount of secretion or discharge
required to carry enough germs to cause infection
is very minute. When the germs are
once located on suitable soil they multiply
rapidly and enormous numbers are soon produced
from an original few. In originating
new cases of disease the secretion from the
sick with its germs is deposited on some part
of the mucous membrane, or lining of the
respiratory tract, as the lining of the nose,
throat or larynx; or enters through the mouth,
and, being swallowed, lodges in the stomach or
intestine. At times the infecting material enters
through wounds and injuries of the skin,
the intact healthy skin usually forming a perfect
protection against infection.
The passage of secretions from the sick person
to others is accomplished in numerous
ways. Sometimes this is through direct contact
between two persons, as in kissing. More
often the contact is indirect, the secretion being
carried on some object. Anything that is
contaminated by secretions may carry them to
a second person. A few of the most common
carriers, such as hands, clothing, bedding, eating
utensils, cups, forks and spoons, toys and
pet animals may be mentioned. During forced
expiratory efforts, such as coughing, sneezing,
hawking, stuttering, loud talking or crying,
small particles of secretions from the throat
and mouth are thrown into the air in the form
of what is known as mouth spray. This may
be inhaled by persons who are near and be
deposited in the throat or nose. This manner
of transferring contagious diseases is not so
frequent as the others mentioned, and only
occurs at distances of a few feet. Secretions
which become dry and pulverized into dust
outside the body soon lose their power of infecting.
Dust is not of much danger as a
means of transferring contagious diseases.
Sometimes various foods which are contaminated
by disease discharges serve to carry
them to well persons, in which case they may
be deposited in the throat or pass into the
stomach or intestines. This is specially true
of milk, which has been responsible for many
outbreaks of scarlet fever and diphtheria. The
disease germs in the milk do not come from
cows, but get into the milk during or after
milking from the hands, sputum and other
means of contact of the persons who handle
the milk.
CARRIERS
In recent years persons who are known as
disease carriers have been looked on as important
factors in the spread of many contagious
diseases. The part they play in diphtheria
has been abundantly demonstrated and
is important. Carriers in this sense are persons
who are well, but who carry about disease
germs in their throats or noses. They
may have recently passed through mild attacks
of the disease whose germs remain for a long
time after recovery, or they may have received
the germs from sick persons, never having
been sick. This condition of carriage may persist
a long time, and carriers are especially
dangerous because not usually suspected.
COMMON PECULIARITIES
Some common peculiarities of contagious
diseases may be mentioned. After exposure
a definite period of incubation passes before
any symptoms develop; many of these diseases
have characteristic skin eruptions; they occur
in epidemics, especially in children, and one
attack usually protects the individual during
life.
PREVENTION
Because of the wide distribution of contagious
disease and the large number of deaths
caused by them, attempts to prevent their
spread have been made from remote times.
This has been largely concerned with isolation
or quarantine of sick persons. Doubtless
these measures have been useful, but that they
have largely failed to accomplish what is expected
of them is not surprising if we bear in
mind that many of these diseases are most
contagious early in their course before they
are recognized and before quarantine is begun,
and if we consider the important part which
is played by healthy carriers who are not suspected
and go about freely.
An ideal condition would obtain if it were
possible to render all children, early in life,
immune to these diseases. In vaccination
against smallpox we have a measure which has
banished smallpox to a large extent and which,
if universally employed, would eradicate the
disease. Similar vaccination measures are now
available for diphtheria and scarlet fever. They
are easily carried out, devoid of danger, and
rarely cause even slight discomfort. These will
be again referred to in discussing the individual
diseases.
QUARANTINE AND DISINFECTION
The term quarantine was originally applied
to the forty days during which a ship suspected
of being infected with a contagious disease was
held before those on board were allowed to
come into contact with those on shore. In
present conditions a better term to use is isolation
which varies in length and severity in
different diseases. The period of isolation in
diphtheria is until the person is free of the
germs which cause the disease. As it is possible
to cultivate and recognize the diphtheria
germs the period of isolation can be accurately
determined. At times it is only a few days;
at other times it must be extended to weeks
or even months. In the case of scarlet fever
and diphtheria the attendant who is liable
to carry infectious materials is isolated with
the patient.
In scarlet fever the isolation is four or five
weeks and until all discharges have ceased.
Discharges from the nose and ear after scarlet
fever are apt to contain the cause of the disease,
and so are dangerous. Epidemics of
scarlet fever have been started in communities
by the coming of a child who still had a running
ear following scarlet fever many weeks
previously.
The danger of transferring measles is quickly
over, and patients may be released after the
fever has been absent two or three days.
In chicken pox the separation of all scabs is
the measure of the isolation period.
Whooping cough is released when the characteristic
paroxyms cease.
If measles or whooping cough appears in a
child in a family, other children may be sent
from home in hope that they have not been infected.
They must not be sent where there are
children who may be infected if the disease
develops.
In diphtheria and scarlet fever the separation
of the sick must be absolute. No communication
must be allowed between the sick
and well. The patient and attendant should
be in a separate building, or in a room which
can be shut off from the rest of the house.
Nothing should pass from the sick room that
is not sterilized at once. All discharges should
be collected on pieces of gauze, and these with
surgical dressings, portions of food, fruit or
other material which the patient may have handled
may be placed in paper bags and burned
without opening. All sheets, towels, pillow
covers and bed clothes should be boiled in water
before being washed. The same disinfection
should be used for eating utensils. After recovery
the patient and attendant should be
given a thorough bath in warm water with
soap. The hair also is washed. In a clean
room fresh clothing is to be put on. After the
isolation room is emptied of its occupants all
its contents are disinfected as thoroughly as
possible. This can be accomplished by boiling
everything which can be treated in this way,
by burning things which have little value and
which cannot be boiled such as books, toys,
mattresses and pillows contaminated by secretions,
by thoroughly washing with warm water
and soap all wood work, floors and furniture,
and by thoroughly airing and sunning the bedding.
The fumigation which was formerly generally
used has been largely discontinued.
Much more can be accomplished by washing,
painting, and removal of paper and replacing
by new. A safe rule is to burn everything
which cannot be boiled in water or thoroughly
cleansed with warm water and soap. Fresh
air and sunshine are most efficient destroyers
of germs. Children recently relieved from isolation
after diphtheria and especially after
scarlet fever should not sleep with well children
for a week or two, and should not be
kissed.
The disinfection required after measles,
whooping cough and chicken pox is limited
and consists of thorough airing and sunning.
It is not desirable to confine children with
whooping cough. They may be taken out of
doors, but must not be allowed to play with
well children. Diphtheria carriers may also be
allowed to be out of doors provided provision
is made for keeping them from well persons.
Their eating utensils, toys, etc., must always
be treated as are those of persons with active
diphtheria.
The closing of schools at the times of outbreaks
of the contagious diseases is of doubtful
value. It does not prevent contact between
the children when at play. Most favorable
conditions for dissemination of contagious diseases
exist in Sunday schools since children
too young to attend school as well as older
children are here brought together. If closing
of schools is to accomplish any good in controlling
contagious diseases it must be combined
with separation of the families of children
at home, and the prevention of children
coming together in picture shows and other
places.
It is hardly necessary to state that no child
who is acutely sick should be sent to school.
So many contagious diseases are impossible
of recognition at the beginning that each case
of sickness must be considered suspicious until
it is shown to be harmless.