OFFICKM-PCM or varicella is seldom seen except in young subjects. It is an infectious disorder which occurs generally in epidemics, and attacks by preference children aged from two to six years. At one time it Was sup posed to be a form of modified small-pox, but few are now of this opinion, for the evidence against it is overwhelming. Attempts have been made to impart the disease by inoculation, but without success.
Symptoms.—After a period of incubation, varying from seven to four teen clays, the child is noticed to be feverish, and within the next four-and twenty hours a number of small rosy-red spots appear on the chest and over the body generally. These are slightly elevated, and number on the first day fifteen or twenty. In the course of a few hours—in any case by the next morning—the papule has changed into a vesicle or roundish bleb which is filled with clear serum. It has sometimes a very faint pink areola round its circumference. At the same time other papules have ap peared, more numerous than on the first day. These in their turn become converted into clear blebs. In this way every morning finds a fresh crop of red spots, and of fresh blebs formed from the red spots of the previous clay. The change from red spot to bleb may take place very quickly ; in fact, the rash has sometimes been described as vesicular from the first. In any case it is completed within ten or twelve hours of the appearance of the red papule. The spots appear in no regular order, but are scattered about all parts of the body and limbs, and may even be seen beneath the hair on the scalp. They are also occasionally found inside the mouth, on the soft palate, the inner side of the cheeks and lips, and at the sides of the tongue ; but when seated on mucous membrane the vesicle changes very rapidly to a small round ulcer. After appearing in successive crops for four or five days, fresh spots cease to be seen. The changes which each individual spot undergoes are as follows :—it increases in size...for a day or two, and then its liquid contents, from clear, like pure water, be come milky. Some burst and form crusts ; others present, after a day or
two, a speck of scab on the summit, which to a hasty glance gives a false appearance of umbilication ; the vesicle then dries up and leaves a thin crust, which falls off after a few days. No scar is left, as in variola, unless the child have irritated the- skin by scratching ; in which case a shallow pit may be seen in the situation of the scab. is difficult to prevent the child from scratching the spots, for the eruption is accompanied by con siderable irritation.
The amount of fever varies. At the beginning the temperature may rise as high as 102°, especially if the rash is slow to appear. After the first day or two, however, the pyrexia subsides considerably, and is seldom higher than 99.5° during the remainder of the illness. In soihe cases a slight exacerbation occurs with the maturation of the vesicles, but the temperature soon returns to the normal level. In the large majority of cases the constitutional disturbance is of the slightest. After the crusts have fallen the temperature sinks to a lower level than in health.
The duration of the disorder is ten days or a fortnight, counting from the preliminary fever to the final fall of the crusts. Afterwards the child may be left in a weakly state for some time ; and delicate children may have the outbreak of serious disease determined by this apparently trifling complaint. Thus, I have known acute tuberculosis to succeed after a very short interval to an attack of chicken-pox.
In exceptional cases the complaint is not over so quickly. Mr. J. Hutchinson was the first to draw attention to the gangrenous eruptions. which sometimes occur in connection with the chicken-pox. This dan gerous complication is not confined to weakly, ill-nourished children, al though it is most common in them. It is no doubt connected with the curious tendency to spontaneous gangrene sometimes met with in chil dren, and described in another chapter.