The reddening of the skin consequent on local application (water, oil) is always limited in extent, confined to the area of application.
Drug eruptions (atropin, aspirin, iodoform, chrysarobin, tuberculin) have also been known to simulate the scarlet fever eruption. knowl edge of the use of any of these drugs and the appearance of the latices will aid in arriving at a correct diagnosis. The tuberculin eruption is purely follicular in character; the individual follicles are red and swollen. The greatest difficulty in diagnosis is presented by the scarlatiniform eruption of serum disease, and the appearance of the pharynx and fauces in a case of diphtheria in recession is such as to make a correct diagnosis almost impossible. Many observers have pronounced every scarlatini form eruption consequent on the injection of serum or antitoxin as indic ative of scarlet fever. That is surely going too far in our diagnosis. Only an intense eruption and a severe angina are diagnostic of scarlet fever. The eruption of serum disease is pink in color and extends from the site of the injection.
The variations in intensity of the pharyngeal inflammation of scarlet fever from a simple redness and swelling to an extensive necrosis of the so-called diphtheritic membrane lead to errors in diagnosis very fre quently, and call for considerable 'diagnostic acumen, particularly in view of the fact that the anginose inflammation of scarlet fever is present before there is any evidence of a skin eruption. In such cases it may be necessary to postpone a diagnosis for twenty-four or even forty-eight hours. However, vomiting, with severe reddening and swelling of the fauces, should always direct attention to the possibility of the case being one of scarlet fever.
Pathognomonic of diphtheria are a spreading of the membrane on the first or second day of the disease to other parts of the pharynx and fauces, the characteristic elastic appearance of the membrane, and its appearance on the uvula, anterior pillars of the fauces and posterior wall of the pharynx. If an eruption also makes its appearance, it is an evidence of mixed infection. In such cases a positive diagnosis must be based on a bacteriologic examination.
As the disease progresses, the nature, extent and localization of the throat membrane are of considerably less value in arriving at a diagnosis of scarlet fever. The slimy character of the membrane, the destruction
of the deeper layers of the mucous membrane and the raspberry tongue arc pathognomonic of scarlet fever rather than of diphtheria. Micro scopic examination of a smear preparation will show an abundance of streptococci. This tendency to necrosis is seen only in syphilis, tuber culosis and scarlet fever.
I saw such a necrosis of the pharyngeal mucous membrane in two sisters, the victims of tuberculosis. Instead of the hyperremia seen in scarlet fever, there was a marked anaemia of the mucous membrane, and a chronic, painless swelling of the cervical lymph-nodes. Finding the tubercle bacillus in the smear preparation increased the difficulty of arriving at a correct diagnosis. Both children also had an advanced tuberculosis of the lungs, which shortly led to a fatal termination in both cases.
To make a correct prognosis in scarlet fever is a matter of no small moment. Even when the onset of the disease is exceedingly mild in character, tempting one to pronounce the case a mild one, all the symp toms may rapidly increase in severity, so that it is impossible to make a correct prognosis on the first or second day of the disease. On the third or fourth day, when the progress of the pharyngeal inflammation may be determined with sonic degree of certainty, the prognosis must be restricted to the primary disease. It is impossible to foresee the occur rence of complications.
From the diagnostic standpoint, Moser divided scarlet fever cases into favorable (1 and 2), doubtful (3), and lethal (4) cases. Prognosis 1 included those cases which did not present any severe symptoms, in which there was a low temperature, slight or no pharyngeal involve ment, typical eruption and no constitutional symptoms. Prognosis 2 included those cases in which certain symptoms were predominant, being more severe than others, without apparently being inimical to life, such as a moderate degree of pharyngeal involvement, the nose not being affected, intense eruption, with no evidence of cardiac weakness (absence of cyanosis, cold and clammy skin, pulse of good quality), high temperature.