The course of measles in normal cases is well defined and as men tioned above may be divided into several stages. The whole period may he put down as about three and a half weeks. We differentiate thus: first, the period of incubation from the beginning of infection lasting ten or eleven days, and this leads to, second, the actual onset. of the disease as shown by the outbreak of the catarrhal symptoms. This is the initial or prodromal period and lasts two to four days, so that on the thirteenth or fourteenth day of infection we have the period of eruption characterized by the outbreak of the rash. The rash persists three to five days and within this period it fades and disappears. This period represents the crisis of the disease, and the passing into the stage of convalescence, which in uncomplicated cases rapidly and immedi ately closes the attack. For a week longer, on prophylactic grounds, isolation precautions should be observed.
Abnormal Course, and are ushered in by a fresh rise of temperature of a remittent or intermittent type, or no fall may occur, a lower grade be struck, and a continuous type of fever be maintained. The most desperate form is that described as septic mea sles, which within a few days runs a rapid course to a fatal issue. It is probably the lessened resistance of the individual to the virus of measles, that accounts for the severe signs of prostration, the high fever and the acute course of the disease, which toward the end of its course shows a striking similarity to file toxic forms of scarlet fever. It may occur at any time of life. While the blood findings in these fulminating cases of scarlet fever are always negative, in the blood of septic measles on the other hand a double infection with streptococcus is found. The paren chymatous organs always show marked degenerative changes.
During measles and following it, there are certain visceral compli cations which must be considered. The skin may first be mentioned. An obstinate eczema showing a variety of characters may be associated with measles; as for instance, fine nodules may develop and these may coalesce and awake suspicion as to the existence of a new form of measles rash. The rash is often pustular, pemphigoid, or in character where there has been neglect. in the care and nursing. Ecthyma with its indurated inflammatory base is also found in such neglected children, situated particularly on the buttocks, and in the genital regions. The tendency to necrosis of the skin and mucous mem branes is marked but fortunately noma rarely develops. I once saw in the course of measles a well-marked dry gangrene of the prepuce, yet it was without hindrance to the ultimate recovery of the child.
A skin eruption only recently much observed is nodular in charac ter and tuberculous in origin. The nodules are scattered, reaching that of a lentil in size, brownish in color, sometimes with a blue discolora tion, often yellow, they are somewhat shiny in appearance, and the infiltration is sharply outlined; these are described as tuberculidcs (see article by Leiner in Volume IV. of this work). They are a definite
expression of tuberculous infection, and are frequently seen in tubercu lous individuals in association with measles.
The respiratory tract is the most frequent seat of complications. The measles virus alone or a mixed infection may work serious damage. The nasal mucosa, undergoes inflammatory changes, and the resulting swelling, particularly of the mucosa, may persist and interfere with nasal breathing. In children in the first year of life, as a result of insuf ficient care, the nasal secretions excoriate the skin about the nostrils, and the lips, as well as the nose itself, swell up and become the seat of scrofulous infiltration. The skin and mucous membrane thus stretched crack, and deep fissures may form which give the patient great pain, and in addition offer a favorable site for the entrance of various infecting organisms. Commonly micrococci are the cause of these septic fissures, not infrequently it is the bacillus of diphtheria. This latter organism readily infects the patient in the course of measles, and it is quite evident that as a result of measles, a distinctly lessened resistance to diphtheria is shown, and the nose, throat, skin, eyes, genitals, but the larynx in particular, are the points of implantation of this unusually rapid infection. The portions of the skin infected by diphtheria some times show an early and striking tendency to necrotic change which may lead to extensive ulceration.
Croup arising during measles is not always necessarily of a diph theritic nature, yet this form often occurs. Sometimes a membrane forms in the throat, and may extend to the bronchi, yet repeated bac teriological examinations may fail to demonstrate the presence of diph theria. This condition is recognized clinically by the more yellow color and loose adhesion of the membrane and shows micrococci alone or some times influenza bacilli. A peculiarity that may be mentioned is that in spite of the extension of the membrane into the larynx and below it, the throat may often be free, or show but little membrane. The signs of croup can be produced by swelling of the mucosa without the pres ence of any membrane whatsoever. Another cause of pseudocroup is an aphthous inflammation of the mucosa of the mouth and larynx, moreover without the laryngeal mucous membrane being affected. These so-called laryngeal signs may be produced by a marked inflamma tion as a result of an aphthous stomatitis spreading from the throat. The development of aphthde in measles and scarlet fever is especially variable in character and extent. By reason of the tendency to necrosis it may produce extensive grayish yellow discoloration of the mucosa, i.e., epithelial necrosis. Deeper losses of substance such as are so frequent in scarlet fever, are rarely found in measles.