DIPHTHERIA, or DIPIITHERI'TIS (Fr. dip/Amite, from Gr. dipkthera, a pellicle), a name first applied by M. Bretonneau of Tours, a distinguished French physician, to a form of very fatal sore throat occurring epidemically, chiefly in children, and apt to be confounded both with croup (q.v.) and with malignant sore throat angina malign), as it is found in connection with scarlet fever (q.v.). Diphtheria is distinct from both these diseases, not only in its symptoms, but in the character and position of the morbid changes on the mucous membrane. In croup, there is a pellicular membrane, indeed, but it is almost confined to the air-passages, and centers in the larynx (q.v.); in diphtheria, it usually begins in the pharynx or back of the throat, and often extends down the esophagus, or gullet. Croup is also a much more decidedly inflammatory disease than diphtheria. Malignant or ulcerative sore throat has even less in common with diphtheria; for in the latter there is no ulceration in the majority of cases, the mucous membrane being merely covered over with a more or less thick veil of false membrane; in both affections, however, there is enlargement of the glands behind the ear and in the neck, generally in the neighborhood of the parts internally affected. The throat affection in diphtheria is often accompanied by a very low and dangerous form of fever, with great and rapid loss of the patient's strength, which is still further reduced of course by the inability to take food; in other cases, the disease is fatal by suffocation, and tracheotomy has been performed (in some few instances successfully) to relieve the patient from impending death. After the acute disease is over, the recovery may be delayed by
paralytic symptoms of various kinds; or simply by extreme debility, with exhaustion and loss of appetite. Diphtheria was supposed by Bretonneau to be contagious, but it is doubted by many whether the evidence of contagion is sufficient. There is no good evidence of any specific cure. The use of the tincture of muriate of iron in large doses (fifteen to twenty drops frequently repeated) has been recommended; also various disin fectants and caustics applied to the throat, as nitrate of silver, hydrochloric acid mixed with honey, and latterly Condy's disinfecting fluid; but all of these have also frequently failed in the hands of experienced physicians. Diphtheria does not appear to be so much under the influence of known sanitary conditions as other epidemics; at least its modes of origin and diffusion are still extremely uncertain.