MEASLES (Morbilli, Rubeola), an acute infectious disease occurring mostly in children, and possibly caused by a filter passing virus (q.v.). The course of the disease is as follows. After exposure to infection, for from eight to twelve days there is an incubation period unaccompanied by evident symptoms. Then follows the sudden onset of acute catarrh of the mucous membranes. Minute white spots in the buccal mucous membrane frequently occur, and are diagnostic if present. Sneezing, a watery discharge, sometimes bleeding, from the nose, redness and watering of the eyes, dry, noisy cough, hoarseness, and occasionally sickness and diarrhoea, characterize this stage. With these, fever (102° 104° F), abating after the second day, rapid pulse, headache, thirst and restlessness are usually present. In young children, convulsions may usher in, or occur in the course of, this stage, which lasts for four or five days. On the fourth or fifth day after the invasion, the characteristic eruption appears on the skin, being first noticed on the brow, cheeks, chin, behind the ears and on the neck. It consists of small dusky red or crimson spots, slightly elevated above the surface, at first isolated, but tending to become grouped into patches of irregular, occasionally crescentic, outline, with portions of skin free from the eruption intervening. The face acquires a bloated appearance, which, taken with the catarrh, renders diagnosis at this stage a matter of no difficulty. The eruption spreads downwards over the body and limbs, which are soon thickly studded with the red spots or patches. Sometimes these become confluent over a considerable surface. The rash con tinues to come out for two or three days, and then begins to fade in the order in which it first showed itself, namely from above downwards. About a week after its first appearance nothing re mains beyond a faint staining of the skin. Usually during con valescence slight, branny desquamation occurs. At the commence ment of the eruptive stage the fever, catarrh, etc., become ag gravated, the temperature often rising to 1o5° or more, and red patches similar to those on the surface of the body may be ob served on the throat. These symptoms usually decline when the
rash has attained its maximum, the temperature falling suddenly. In favourable cases convalescence is rapid.
Measles may, however, occur in a very malignant form, the rash being feebly developed, and dark purple, while there is great prostration with intense catarrh of the respiratory or gastro intestinal mucous membrane. Such cases occur mostly in cir cumstances of bad hygiene or in isolated communities that have long been free from epidemics of measles. On the other hand, cases of measles are often so mild that other treatment than a few days in bed, is unnecessary.
Measles derives its chief importance from the risk of pul monary complications. These are most frequent in the colder seasons of the year and in very young and delicate (particularly, rickety) children. Under these conditions the catarrh instead of abating, advances, and bronchopneumonia (see BRONCHITIS, PNEUMONIA) supervenes. By far the greater proportion of the mortality in measles is due to this complication. Or there may remain as direct results of the disease chronic ophthalmia, or dis charge from the ears with deafness, and occasionally a form of gangrene affecting the tissues of the mouth or cheeks and other parts of the body, leading to disfigurement and gravely endanger ing life.
Apart from those immediate risks there may remain after measles a weakened condition of the general health, which paves the way for subsequent tuberculosis.
Measles is a disease of the earlier years of childhood, though not unknown in nurslings or infants under six months old. It is rare in adults, since an attack in childhood mostly confers im munity for the rest of life. All races of men appear liable, and when a community has long been immune from outbreaks intro duction of infection is followed by a devastating epidemic. Thus in Fiji in 1875 it was estimated that about one-fourth of the inhabitants died within three months.