Diphtheria
a contagious and (in its severe forms) malignant disease, caused by a specific bacillus and generally characterized by the formation of a fibrinous false membrane in the throat.
Although previously observed, it was first clearly described in 1826 by M. Bretonneau of Tours under the name of "diphterite," as a form of very fatal sore throat occurring chiefly in children. It is now known that most cases of membranous croup are identical with diphtheria. The period of incubation is usually from two to seven days. The disease begins by malaise, feeling of chilliness, loss DIPHTHERIA of appetite, headache and more or less fever; soon the throat feels hot and painful and the neck is stiff and tender. If seen early, the throat is red and swollen, but a false membrane of yellowish or grayish color quickly appears in spreading patches, usually first on the tonsils, whence it often spreads to the pillars of the fauces, uvula and back of the throat, and may even extend down the œsophagus or gullet; extension of the membrane into the nasal cavities is a grave symptom. There is usually enlargement of the glands at the angle of the jaw, and albuminuria generally occurs at some stage of the disease. Diphtheritic membrane may be formed on any mucous surface, or even on a wound; if it extends into the larynx it gives rise to cough and difficulty in breathing. The throat affection is often accompanied by a low and very dangerous form of fever, with quick, feeble pulse and great and rapid loss of the patient's strength, which is still further reduced by the inability to take food; in other cases, the disease is fatal by paralysis of the heart or by suffocation, due to invasion of the larynx. Invasion of the larynx may necessitate intubation or tracheotomy. 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. In the early stages of convalescence there is danger of sudden heart failure upon exertion.
Diphtheria is contagious. It may occur as a complication of scarlet fever, measles, and other infectious diseases. All gradations in the intensity of the disease from mild sore throat to septic and gangrenous forms occur. Damp and temperate climates seem to favor its development. Insanitary conditions favor its occurrence, but the disease may appear under the most favorable hygienic surroundings.
True diphtheria is now known to be caused by a specific bacillus called bacillus diphtheria, or the Klebs-Löffler bacillus. This bacillus was first recognized by Klebs in 1883 by microscopical examination of diphtheritic membranes, but it was first successfully cultivated by Löffler in 1884. Its causal relation to the disease was not thoroughly established till the investigations of Roux and Yersin in 1888, who demonstrated the existence of a peculiar and intensely poisonous substance known as the diphtheria toxin. It is now generally admitted that the Klebs- Löffler bacillus is the cause of true diphtheria. The diphtheria bacillus is a slender rod characterized especially by irregularities in shape and staining with aniline dyes.
DIPHTHONG DIPNOI The animal is supposed to have been a hippopotamus-like wader, and to have lived on vegetation in the water.
The ways in which diphtheria bacilli Jurassic deposits. The length of skull may be conveyed from sick to healthy of this species was about 21 inches, of persons are almost countless. In ordi- brain about 3 inches, and of body 50 feet. nary breathing the expired breath contains no germs, but in speaking and especially in coughing, a fine spray is emitted which may contain the bacilli and thus convey the disease. All sorts of articles, such as handkerchiefs, toys, drinking utensils, furniture, clothing, bedlinen and the like, may become contaminated with the bacilli and be the means of spreading the disease. Hence, preventive measures, consisting in isolation of the patient till the bacilli have disappeared from the throat and in thorough disinfection, are of the first importance in checking the spread of diphtheria.
The discovery of the diphtheria bacillus has led to the introduction of a new and most successful method of treatment of the disease, known as serum-therapy or the antitoxin treatment. The establish ment of the principles and the introduction of this treatment are due especially to Behring of Germany and Roux in Paris. The underlying principle of the treatment is based on the fact that, if a susceptible animal is inoculated first with small and then with increasing doses of the toxin produced by the bacillus, the blood of the animal is found to contain a substance called antitoxin, which has the power of neutralizing or rendering harmless the toxin. In order to obtain large quantities of the healing serum a horse is generally selected for the process of immunization. By proper methods very powerful antitoxins can be obtained.
The antitoxin is used not only to cure the disease, but also to render persons insusceptible for a time to the disease. Dr. William H. Welch, of the Johns Hopkins University, in 1895, in an analysis of over 7,000 cases of diphtheria treated by antitoxin found that the fatality was reduced by this treatment by over 50 per cent of the previous death-rates. Since his report this conclusion has been confirmed and even more favorable results have been obtained.