The symptoms may be considered as they occur in three stages;
catarrhal, eruptive and convalescent. After infection no signs of
illness appear for several days. This is the period of incubation.
About eight to ten days after exposure, very fine, pin-point size spots
appear on the lining of the cheek opposite the molar teeth. These are
known as Koplik spots. They are bluish-white in color and seen only by
bright daylight. About the same time catarrhal symptoms appear, such
as a little fever, coryza, sneezing, hoarse cough, watery eyes. The
symptoms as they occur in this catarrhal stage of measles are usually
supposed to be due to a cold. After a further three, four or five days,
i. e.--12 to 13 days after exposure--the typical eruption appears.
It is first seen over the forehead at the border of the hair, behind
the ears and on the neck. This gradually spreads during two or three
days over the face, body and finally the arms and legs. The eruption
occurs as small red spots or blotches, round or oval in form. They
tend to become larger and finally run together, so that at the height
of the eruption the skin of the face and body is completely covered,
only small islands of pale skin appearing. The color of the eruption
is deeper red than that of scarlet fever, and is much coarser. During
the time the eruption is coming out the fever is often high and the
catarrhal symptoms are marked. Light hurts the eyes, and they become
bleary red, the secretions causing the lids to stick together during
sleep. The cough is often very troublesome. At first it is dry and
later looser. There is often hoarseness and sometimes the patient can
talk only in a whisper. When the eruption has reached its height it
soon begins to fade, but traces often remain for a week or more. As the
eruption begins to fade the fever falls, often very rapidly. A fine
branny scaling of the skin follows the fading of the eruption.