Diphtheria (Gr.Diphtheria 060058membrane), the name of a disease which has heretofore received a variety of appellations, such as ulcus AEgyptiacum vel Syriacum, cynanche maligna, angina maligna, angina gangroenosa, morbus suffocant vel strangulatorius, garrotillo, angina suffocativa, malignant sore throat, epidemic croup, etc. The term diphtherite was applied to it by Bretonneau in 1821, whence originated the name diphtheria which is now in common use, relating to the formation of a false membrane in the throat and in other situations, analogous to that which characterizes the disease called, among other names, diphtheritic laryngitis, or true croup. (See Croup.)

Recent microscopical observations, however, appear to show points of difference between the pseudo-membranous morbid product in the two diseases. In diphtheria the false membrane, accompanying inflammation, appears almost invariably in the fauces or throat, and in many cases it is limited to this situation. It may extend more or less over the mucous surface within the mouth and nostrils. It is not infrequently produced within the windpipe, giving rise to all the symptoms of true croup, and generally proving fatal. Mucous surfaces elsewhere are in some cases the seat of this peculiar form of inflammation; namely, in the eyes, the ears, the organs of generation, etc. A similar false membrane is produced in some cases on the skin, in situations where there may be either wounds, abrasions, or sores. The local affections thus characterized cannot be said to constitute the disease, but they are to be considered as the manifestations of a morbid condition of the system, probably involving special blood changes, the essential nature of which is at present unknown. In other words, diphtheria belongs among the diseases which are distinguished nosologically as general or constitutional. The disease rarely occurs except as an epidemic.

Epidemic diphtheria has occurred in all countries, but in the United States only occasional sporadic cases were observed during the first half of the present century. Since about 1856, however, there have been repeated epidemics in different parts of the country. Whether it be one of the communicable diseases, that is, diffused by contagion or infection, is an open question. Persons between 3 and 12 years of age are most apt to be affected with it, but no period of life is exempt from a liability to it. The false membranes are found frequently to contain a parasitic fungus, the spores and sporules of a cryptogamic plant; and the idea has been entertained that the disease is due to the presence of these. It seems, however, more reasonable to suppose that they are merely incidental to the local affection, the morbid products furnishing only a proper nidus or soil for their growth and reproduction. Different epidemics differ much in the rate of mortality. The disease is sometimes mild, the local manifestation being confined to the throat, and the constitutional symptoms slight. In other cases it has a degree of violence and a fatal tendency which entitles it to be classed among the malignant diseases. Death sometimes takes place within 48 hours after the attack.

The degree and extent of local manifestations are in general commensurate with the severity and danger. If the larynx becomes affected, the chances of recovery are very few. Frequent vomiting, diarrhoea, haemorrhage from the nostrils or elsewhere, frequency and feebleness of the pulse, convulsions, delirium, and coma are symptoms which denote great danger. If the larynx is affected, death may take place from suffocation. In the fatal cases in which the larynx escapes, the immediate cause of death is exhaustion. Paralysis frequently occurs as a sequel. The muscles of the throat are those most likely to become more or less paralyzed, rendering deglutition difficult and sometimes impossible. With or without paralysis in this situation, the muscles of the lower limbs may be paralyzed, or the muscles of an upper and a lower limb on one side. Occasionally the muscles of both the upper and lower limbs are affected. Vision may be impaired by paralysis of the external rectus muscle, causing strabismus or squinting; and not infrequently far-sightedness, or more rarely near-sightedness, takes place; and amaurosis occurs in some cases. The other special senses, hearing, taste, and smell, are sometimes affected.

These varied paralytic affections generally occur within a few weeks after convalescence from the diphtheria. They are as likely to follow in cases where the disease was mild as where it was severe. As a rule complete recovery takes place, showing that the paralysis does not proceed from structural changes. The disease, when paralysis does not follow, generally leaves the patient feeble and anaemic for a considerable period. Sudden death from syncope has repeatedly occurred after convalescence had been declared, as a consequence of some muscular effort; hence the importance of enjoining quietude until the strength is in some measure restored. - The treatment has been supposed to embrace, as a highly important measure, cauterizing applications to the throat and to the local affection in other situations; the objects being to destroy or modify the special character of the inflammation, to limit its extension, and prevent the absorption of septic matter. Those who consider the efficient cause of the peculiar inflammation to be the presence of cryptogamic formations, are of course led to attach importance to applications which destroy vegetable life.

For the most part, however, in this country, physicians have abandoned severe topical measures, limiting themselves to antiseptic and soothing applications. Clinical experiences seem to establish the propriety of this plan. The chief objects in the treatment are to palliate symptoms, and support the powers of life by the judicious employment of tonic remedies, conjoined with alimentation and alcoholic stimulants. The latter are in some cases given in large quantity without inducing their excitant effects; and there is reason to believe that they are sometimes the means of saving life. In the cases in which the larynx becomes affected, the measures are indicated which belong to the treatment of true croup, and tracheotomy is to be resorted to if necessary to avert death from suffocation. The prospect of success from this operation is extremely small; yet, as it undoubtedly sometimes rescues a patient from impending death, it is the duty of the phy-sician not to withhold the chances of life, however small, which tracheotomy affords.