The cause of diphtheria, discovered in 1883-84 by Klebs and Loeffler,
two German scientists, is the diphtheria bacillus. It is a minute rod
shaped vegetable organism sometimes spoken of as a germ. If it is taken
into the throat and lodges and grows upon the tonsils two results may
follow. If the person is susceptible diphtheria occurs. If the person
is immune no local changes occur and the individual becomes a carrier.
Both may transfer the germs to other persons. We may compare what
occurs here to what happens when persons come in contact with certain
higher plants. The poison ivy vine has in its leaves a specific poison
which causes an inflammation of the skin of some persons who are
susceptible to it, but has no effect upon others who are immune. So the
diphtheria plant as it grows in the throat produces soluble poisons or
toxins which cause the changes we call diphtheria in a susceptible
person, but is without effect on the immune person. The immune person
is protected by an antidote or antitoxin which is in the blood, while
the susceptible person has none. After the diphtheria bacilli have
localized on the tonsil the events which follow may be briefly stated.
In their growth the bacilli produce poisons and as a result the tonsils
become red and swollen. On the surface of the tonsil, where the injury
is greatest, white spots appear, and, as they enlarge, they run
together to form the membrane which is characteristic of the disease.
The name diphtheria means in its derivation a pellicle or skin. This
membrane often extends beyond the tonsils, spreading over the throat,
up to the roof of the mouth, over the palate. Sometimes it goes from
the throat upward into the back of the nose or downward into the
larynx. Wherever the membrane spreads the tissues below are swollen.
In the nose the nostrils become occluded and the patient cannot
breathe through the nose; in the throat the tonsils become very large
interfering with swallowing and breathing. In the larynx the swelling
causes hoarseness, croupy cough, and finally difficulty in breathing
which may terminate in death from strangulation unless relieved. This
is what was formerly called membranous croup. The membrane in the
throat is first white, but as it thickens it becomes grayish-yellow,
like buck skin, and finally may be black. It is closely adherent and
not readily wiped off. When the disease extends to the larynx it tends
to go further along the windpipe until it reaches the lungs with
resulting pneumonia. When the changes in the throat are severe, there
is external swelling of the neck. This may be extreme and is sometimes
mistaken for mumps.
While the things we have spoken of are going on poisons are being taken
by the blood to all parts of the body. In this way they reach and
injure the muscle of the heart, and this injury is of such a degree
in severe cases that it causes death. The poisons in the blood also
profoundly injure the nervous system with resulting paralysis, so
that the eyes are turned to the side, swallowing becomes difficult or
impossible, and the muscles of the body and limbs become weak. These
paralyses appear as late as six to eight weeks after the beginning of
the disease. The symptoms as described are as they occur at the present
time in cases untreated by antitoxin. Some cases are mild and never
reach an extreme degree. In some the laryngeal symptoms develop early
and death from obstruction to breathing may occur before much is seen
in the throat. Sometimes a child who has what appears as a tonsilitis
for several days shows a sudden extension to the larynx. The onset of
diphtheria is insidious. The child acts “dopey”, has a little fever,
and does not usually complain of pain in the throat. A child with acute
tonsilitis is at first apparently much sicker, has more fever and
complains more of soreness in the throat.