Observations have thus far failed to establish any connection in the atmospheric conditions of temperature or moisture and the type of scarlet fever. Grave as well as mild epidemics have occurred in all climates and seasons.

The mortality is nearly equal in the two sexes, but age bears a marked influence on the percentage of deaths. Comparatively few contract scarlet fever under the age of one year, and the period of its greatest mortality, since it is of its greatest frequency, is between the ages of one and six years. The following are statistics bearing on the relation of the age to the percentage of deaths:

Under 1 year.From the close
of 1st till close
of 5th year.		From the 5th to
the 12th year.
Fleishman,Cases8204260
Deaths68851
1st to close of
6th year.		6th to 12th year.From the 12th
to 20th year.
Kraus,Cases1311310640
Deaths429102
7th to 16th year.
Voit,Cases5166109
Deaths12410
1st to close
of 5th year.		Over 5 years.
Röset,Cases4315688
Deaths16313
Under 5 years.5th to 10th year.10th to 15th year.Over 15 years.
Rusigger,Cases1011264727
Deaths212030

These statistics, which I believe correspond with the observations of others, show that although few cases occur in the first year, the percentage of deaths is large, and that a majority of the deaths occur under the age of six years. After the sixth year the greater the age the less the proportionate number of deaths.

Scarlet fever is liable to so many complications and sequelæ that a physician should not predict a certain favorable termination in the beginning, however mild and regular the symptoms may be. But a favorable result may be expected if the attack be mild, the efflorescence appear at the proper time and extend over the entire surface, the angina be moderate and accompanied by little or no cellulitis or adenitis, with pulse under 140, temperature not above 103°, and no marked nervous symptoms.

Whether the complications or sequelæ be dangerous depends upon their character. Rheumatism has never in my practice been dangerous, nor has it materially retarded convalescence, except when it affected the heart, causing pericarditis or endocarditis, when it involves great danger. Nephritis, if it be moderate, attended by little albuminuria and serous effusion, and by the occurrence of few renal casts in the urine, commonly ends favorably under judicious treatment, as we have already stated; but severe nephritis, with abundant albuminuria and casts and serous effusions, soon gives rise to alarming symptoms, and is the cause of death in a considerable number of instances. A similar remark is applicable to the angina, which occurs in all grades of severity. If it be attended by much cellulitis, with considerable ulceration or necrosis, the state is one of danger, in consequence of the difficulty in administering sufficient nutriment, of the diminished assimilation and of the loss of strength from the prolonged inflammatory fever, the septic poisoning, and the occasional hemorrhages. Complication by pharyngeal or nasal diphtheria, now so common where diphtheria is endemic, also greatly increases the danger.

Many cases, even when their course is normal and without complications, involve danger, and some are necessarily fatal, from the direct effect of the scarlatinous blood-poisoning. Such are grave or malignant forms of the disease which the experienced eye recognizes at a glance. Death often occurs rapidly from the toxæmia. Such cases are characterized by high temperature (105° or 106°), rapid pulse, a dusky-red hue of the surface from languid capillary circulation, pungent heat, frequent vomiting, diarrhoeal stools, a dry-brown tongue, and marked nervous symptoms, such as delirium, great restlessness, or stupor. Not a few in this form of scarlet fever take eclampsia, which is apt to be severe and repeated, and to end in fatal coma.

Other inflammatory complications and sequelæ, which have been described in the preceding pages, retard convalescence and jeopardize the life of the patient, such as empyema, endocarditis, pericarditis, and pneumonia. Otitis media is seldom immediately dangerous, although it may be painful and involve serious consequences, even a fatal meningitis, as has been stated above, after months or years of otorrhoea. Anomalous cases are believed to be, as a rule, more dangerous than such as are attended by an early and full efflorescence and have the usual symptoms.

TREATMENT.—PROPHYLAXIS. Since the discovery by Jenner of the prophylactic power of vaccination as regards small-pox, the attention of the profession has been frequently directed to the prevention of scarlet fever. Belladonna has been employed for this purpose by a class of practitioners who believe in the theory that an agent which produces symptoms similar to those of a disease is antagonistic to that disease, and therefore tends to prevent it, or, if it be present, to render it milder; and since this herb causes an efflorescence upon the skin and redness of the fauces, it was selected as the proper preventive and remedial agent for scarlet fever. Its use, however, for this purpose has been fruitless, and it is now nearly or quite discarded.

It is probable, from a considerable number of observations, that scarlet fever occasionally occurs in the domestic animals during epidemics of the disease in children. It is stated that Spinola observed it in the horse; that Heim saw a dog that occupied the same bed with a scarlatinous patient sicken with fever, which was followed by desquamation; that Letheby saw scarlatina in swine, and Kraus in young cattle. Prominent veterinary surgeons, as Williams of Great Britain, admit the occurrence of scarlatina in animals, and the hope has arisen that since small-pox is modified in cattle so as to afford us the vaccine virus, perhaps scarlet fever may also be modified by passing through one of the lower animals, so that a milder and less fatal form of the disease might be produced in man by inoculation from the animal. This theory, though it deserves investigation, is far from being established. It has not yet, so far as I am aware, been shown that scarlet fever is milder in any animal than in man, nor, if we admit that it is modified in the animal, is it certain that the disease could be returned to man in the modified form. In the N.Y. Medical Record for March 24, 1883, some experiments are detailed by S. W. Strickler of Orange, New Jersey. He cites the experiments of Caze and Feltz, who injected scarlatinal blood under the skin of sixty-six rabbits, and of these sixty-two died within eighteen hours to fourteen days, which indicated a highly poisonous state of the blood employed, either septic or scarlatinous, and certainly no mitigation of the virulence of the scarlet fever. Strickler obtained from Williams of Edinburgh nasal mucus from a horse supposed to have scarlatina, and with it inoculated twelve children, all of whom had sores at the point of inoculation, with redness of the skin around the sores, and in some instances swelling of the adjacent lymphatic glands. It is stated that the children thus inoculated did not contract scarlet fever subsequently when they were exposed to scarlatina. Obviously, there is a serious objection to such experiments upon children, so that they may not be repeated, but a movement has been made in one of the New York medical societies looking to the appointment of a competent committee to investigate them. Some of the prominent veterinary surgeons of this city do not attach much importance to the experiments thus far made, as they are in doubt whether the virus employed was that of the genuine disease.