The duration of the period of invasion in regular cases is from three to five days, with an average of about four, but in perfectly uncomplicated attacks this period may be extended to six or eight days, or even longer. But that the duration of this stage may be much shorter than the average is not sufficiently insisted upon by writers. Ringer,22 for instance, says that he had an opportunity of testing the earliest appearance of the rash in an epidemic of measles in a large public school for boys under twelve. In every case during the epidemic the rash appeared on the first day, the cases being severe, though of short duration, the temperature rising to 103° and to 104° F. In some instances the rash preceded (?) the fever. Thus, several of the boys feeling poorly, their temperature was carefully taken night and morning under the tongue, and in several cases the rash appeared in the morning about the face and collar-bone, while the temperature remained normal, and did not rise till the evening, when it ran up to 101°-103° F., and even higher. These cases certainly resemble rötheln more than measles. In two cases, which I observed under very favorable conditions, the eruption commenced to appear on the morning of the second day, and more or less similar experiences are recorded by others.
22 Handbook of Therapeutics, 6th ed., London, 1868—note to p. 26.
The skin eruption, which appears, as a rule, on the third, fourth, or fifth day of the attack, is ushered in with an increase in the general and local symptoms of the disease. It is particularly to be remarked that the fever does not subside at this time, as is the case in variola. The eruption appears first upon the face, about the cheeks and forehead, then on the chin and neck, and thence gradually overspreads the trunk, and finally reaches the extremities. When the eruption is intense no part of the body is free from it, the rash being found upon the palms and soles and upon the hairy scalp. The cutaneous lesions proper consist at first of hyperæmic spots of about a line in diameter, which gradually increase in size, until at their full development they may attain a diameter of from one-twentieth to a quarter of an inch. In the beginning they bear a very close resemblance to the sub-papular lesions of small-pox. The maculo-papules, when fully developed, are slightly elevated above the level of the skin, the elevation, however, being more appreciable to touch than sight, have a smooth velvety feel, and are so arranged as to enclose areas of healthy skin. In the individual spots we may frequently observe one or several minute, darker-colored papules, due to follicular congestion, which when more intense constitutes the morbilli papulari presently to be described. The maculæ are, as a rule, roundish, or they may be moon-shaped, or their borders may present an indented or notched appearance. Where the capillary circulation is active—on the cheeks, for example—or upon parts subjected to pressure, the eruption may become confluent; that is to say, the usually pale intervening skin becomes injected or the papules coalesce, and in this way produce a uniform redness over large single tracts of skin. This scarlatinoid rash, however, never occupies the whole surface of the body, but only limited regions, and in other situations may be detected the characteristic discrete papules of rubeola; the color is not uniform, but is broken here and there by the darker streaks and spots of the measly eruption. The rash, which disappears upon pressure to return when the pressure is removed, is of a more or less rosy red, with a tendency in some to deep red, and has occasionally a purplish hue. According to Mayr and Hebra, it is of the precise color which is obtained by adding a little yellow or brown to a red pigment.
According to the researches of Thomas, Squire, and Wunderlich, as abstracted by Seguin, the fever of the eruptive period is divided into a moderately febrile stage and the fastigium or acme. The moderately febrile stage averages thirty-six to thirty-eight hours, and is made up of one or two exacerbations of 100.4° to 102.2° F., but not quite so high as the initial fever. If there are two exacerbations, the second one is the higher; the intervening remissions are not so low as those of the prodromal stage, yet even now the norm may be noted on a single occasion. The fastigium commences early in the day or in the evening; if the rise should occur in the morning, the evening temperature rises still higher, with or without a slight remission the following morning, and the next evening attains the maximum. If the acme begins in the evening, the remission on the next morning is either absent or very slight. The greatest height of the fever in normal cases corresponds to the greatest intensity and development of the eruption. This rule is not invariable, however, for sometimes the fever is higher soon after the eruption appears, and has fallen when the exanthem has reached its highest point. The whole fastigium lasts from one and a half to two and a half days, so that the complete eruptive fever occupies from three to four and one-half days.23 The pulse in general preserves a proportionate correspondence to the temperature, and never attains the great frequency to be observed in scarlatina.
23 According to Ringer, the highest temperature reached in normal cases is 103° F. Thomas places it as high as 104° F., but states that it may go up to 105° F. without the intervention of any complication.
The general symptoms, with the exception of the fever, do not greatly differ from those common to the prodromal stage. The skin is hot and more or less swollen, particularly about the face; there are anorexia, photophobia, lachrymation, and sometimes epistaxis; the cough continues, and is generally frequent and harassing, and attended with little or no expectoration; the voice is hoarse. The tongue is coated, principally in the middle, through which the swollen papillæ protrude, while the tip and sides are red. The blotchy redness of the oral cavity is visible for some days, and finally becomes indistinguishable from the surrounding congestion. The tonsils sometimes become considerably enlarged, though suppuration must be rare. Enlargement of the glands behind the jaw and in the neck and groin are to be observed. At the outset of the eruption a profuse diarrhoea supervenes in most cases—a symptom which Trousseau rightly insists to be an essential feature of measles. This occurrence is interpreted by some writers as an evidence of the implication of the mucous membranes in the specific exanthem of the disease. This flux, which is sometimes accompanied by a little blood and tenesmus, rarely continues long, and may be succeeded by a degree of constipation. The respiration is generally somewhat accelerated, mostly in correspondence to the amount of fever present. Some degree of deafness is not uncommon, owing to the extension of inflammation along the Eustachian tubes. The urine is scanty and high colored; there is sometimes scalding in urination and vesical tenesmus, and at the acme of the fever traces of albumen may be detected.
The eruption, in fact, generally occupies the skin an average of four days, and, although this period may be shortened materially, it is less apt to be lengthened. The duration of the eruption at its maximum of development over the whole surface is about half a day, more or less, and, as a rule, corresponds with the greatest elevation of the temperature. The retrocession of the rash takes place in the order of its appearance—viz. first from the face, then from the trunk and upper parts of the extremities, and last from about the feet and hands, where, indeed, it may remain vivid, or even progress for a short time longer, after the eruption has begun to subside in other situations. Sometimes the almost faded spots will be temporarily renewed by an abnormal rise in the temperature.
With the decline of the eruption the other symptoms begin to subside. The cough loses its hacking, paroxysmal character, and becomes less and less frequent, and gradually disappears. The voice regains its normal tone, the tongue loses its fur, cleaning up in patches, and expectoration, which was absent or scanty and viscid in the beginning, increases and is free, the masses coughed up being coin-shaped and floating in a clear watery mucus—a symptom much dwelt upon by the older writers. The behavior of the temperature at this period—the stage of decline—is quite characteristic. The fall usually begins at night, and generally the next morning it has reached the norm or else fallen below it. On the other hand, the descent may be less precipitate, and the fall continues less rapidly all through the day; or there may be a slight rise again in the evening, the norm being reached the following morning. The termination by lysis—that is, slight elevations in the evening for several days—is much rarer, and while it may occur in perfectly regular cases, it should put the medical attendant on his guard against complications.
The comparatively normal course of measles portrayed in the preceding paragraphs does not always occur, but, on the contrary, the disease may depart from the more usual type in one or more particulars, either in especial stages of its progress or in the greater or less intensity of the malady as a whole.
In addition to those cases of measles where the eruptive and catarrhal symptoms are so slight as to almost escape observation, except for the existence of other cases in the same house or family, there are to be recognized two other trivial varieties of the disease—namely, measles without the catarrh, and measles without the rash.