ratory
mucous membrane predisposes to it.

Cause.--The exciting cause is a bacillus called after the
discoverers--Klebs-Loeffler--and this may be communicated directly to
another person from the membrane or discharges from the nose and mouth,
secretions of convalescents, or from the throat of normal persons. The
local condition (lesion) may be a simple catarrhal inflammation, or a
greenish or gray exudate, involving chiefly the tonsils, pharynx, soft
palate, nose, larynx and trachea, less often the conjunctiva and
alimentary tract. It is firmly adherent at first and leaves a bleeding
surface when detached; later it is soft and can be removed.

Symptoms.--Incubation period usually lasts from two to seven days after
exposure, usually two, generally there is chilliness, sometimes
convulsions in young children, pain in the back and extremities and a
fever of 102-1/2 to 104 degrees.

PHARYNGEAL DIPHTHERIA.--In typical cases this begins with slight
difficulty in swallowing, and reddened throat (pharynx), then there is a
general congestion of these parts, and membrane is seen on the tonsils. It
is grayish white, then dull or yellowish; adherent and when removed it
leaves a bleeding surface upon which a fresh membrane quickly forms. If
the disease runs on, in a few days the membrane covers the tonsils and
pillars of the fauces, often the uvula. The glands around the neck often
enlarge. Temperature 102 to 103 degrees. Pulse 100 to 120. The
constitutional symptoms are usually in proportion to the local condition,
but not always. The membrane frequently extends into the nostrils and
frequently there is a burning discharge. In malignant cases all the
symptoms are severe and rapidly progressive ending in stupor and death in
three to five days. Death may occur from sudden heart failure or
complications.

[INFECTIOUS DISEASES 185]

[Illustration: Diphtheria (view of infected throat)]

LARYNGEAL DIPHTHERIA, Formerly Called Membranous Croup.--Diphtheria in
the larynx may occur alone or with the pharyngeal kind, and was formerly
called "Membranous Croup." After several days of hoarseness and coughing
the breathing suddenly becomes hard, generally at night, and it is at
first in paroxysms, but later it is constant. The space above the breast
bone (sternum) is depressed and there is a drawing in of the spaces
between the ribs during inspiration accompanied with a husky voice and
blue look. The fever is slight. If the obstruction in