The consideration of diphtheria will be limited to emphasizing the importance of calling in expert medical advice at the earliest possible moment in suspicious cases of throat trouble. For, as we noted under tonsilitis, it is impossible in some cases to decide, from the appearance of the throat, whether the disease is diphtheria or tonsilitis. A specimen of secretion removed from the throat for microscopical examination by a bacteriologist as to the presence of diphtheria germs alone will determine the point. When such an examination is impossible, it is always best to isolate the patient, especially if a child, and treat the case as if it were diphtheria. Diphtheria may invade the nose and be discoverable in the nostrils. A chronic membranous rhinitis should be treated as a case of walking diphtheria.

Antitoxin is the treatment above all other remedies. It has so altered the outlook in diphtheria that, formerly regarded by physicians with alarm and dismay, it is now rendered comparatively harmless. The death rate has been reduced from an average of about forty per cent, before the introduction of antitoxin, to only ten per cent since its use, and, when it is used at the onset of the disease, the results are much more favorable still. This latter fact is the reason for obtaining medical advice at the earliest opportunity in all doubtful cases of throat ailments; and, we might add, that the diagnosis of any case of sore throat is doubtful, particularly in children, whenever there is seen a whitish, yellowish white, or gray deposit on the throat. Antitoxin is an absolutely safe remedy, its ill effects being sometimes the production of a nettlerash or some mild form of joint pains. In small doses, it will prevent the occurrence of diphtheria in those exposed, or liable to exposure, to the disease. The proper dose and method of employing antitoxin it is impossible to impart in a book of this kind. Paralysis of throat, of vocal cords, or of arms or legs partial or entire is a frequent sequel of diphtheria. It is not caused by antitoxin.

The points which it is desirable for everyone to know are, that any sore throat with only a single white spot on the tonsil may be diphtheria, but that when the white spot or deposit not only covers the tonsil or tonsils (see Tonsilitis) but creeps up on to the surrounding parts, as the palate (the soft curtain which shuts off the back of the roof of mouth from the throat), the uvula (the little body hanging from the middle of the palate in the back of the mouth), and the bands on either side of the back of the mouth at its junction with the throat, then the case is probably one of diphtheria. But it is often a day or two before the white deposit forms, the throat at first being simply reddened. The fever in diphtheria is usually not high (often not over 100° to 102° F.), and the headache, backache, and pains in the limbs are not so marked as in tonsilitis.