pustulosa presents only a superficial resemblance to variola, but in cases where it is accidentally associated with an acute febrile disease, like grippe, for instance, it may give rise to some diagnostic difficulty. In these cases, however, inquiry will develop the fact that the acne lesions have been present before the inception of the febrile disease; and the presence of comedos, the limitation of the lesions to the face, chest, and back, together with the absence of any lesions on the palms and soles, will serve to exclude smallpox.

Impetigo Contagiosa.—In impetigo contagiosa there might under similar circumstances be a momentary doubt as to the nature of the illness. Impetigo lesions have no typical distribution on the surface, the mucous membranes are always exempt; the vesicle itself is extremely superficial, ruptures very readily, and is at once replaced by a crust, so that lesions in various stages, vesicles, pustules, and crusts may always be seen at the same time.

Zoster.—Zoster is, as a rule, readily distinguished by the definite grouping of the lesions in the tract supplied by one or more nerves, its asymmetrical distribution, and the more or less severe neuralgic pain that precedes or accompanies the eruption. It must be remembered, however, that in zoster, in addition to the typical grouped lesions, there are occasionally seen a few isolated vesico-pustules scattered promiscuously over the entire surface; and the difficulty of diagnosis may be increased by the occurrence of a moderate temperature movement. In these cases, to which attention was first called by Teneson, the history of the case, the presence of characteristic herpetic groups, and the evolution and course of the individual lesions will suffice to clear the diagnosis.

Drug Eruptions.—The ingestion of bromides, iodides, and quinine is sometimes followed by an eruption which may create some confusion in diagnosis. In general the drug eruptions may be distinguished by the absence of fever and of the subjective symptoms of smallpox. The bromide and the iodide acne never occur on the palms and soles, where there are no sebaceous glands, and the lesions lack the evolution and course of the variolous eruption. The erythematous and purpuric eruption of quinine may be confused with the hemorrhagic form of smallpox; but here, too, the history of the course of the illness and the absence of fever will obviate the difficulty.

Syphilis.—Of all the diseases of the skin it is the pustular syphilide which most resembles the lesions of smallpox. Dermatologists and experts in variola are agreed that the pustular syphilide may be absolutely indistinguishable from smallpox so far as the appearance and distribution of the lesions is concerned. Furthermore, the pustular syphilide is frequently accompanied by a decided febrile movement. The differential diagnosis can be made in these cases only by the closest inquiry into the history of the case and by careful observation of the course of the disease. The characteristic history of an acute illness of short duration followed by a remission on the appearance of the eruption will of course be wanting in syphilis. The syphilitic eruption is more sluggish in its evolution as well as in the course of its subsequent changes; and though there may be lesions of syphilis on the mucous membrane of the mouth, they will lack the characteristic appearance of the vesicles and pustules of smallpox in this region. The palms and soles are not apt to show any lesions in this form of syphilis; and finally some other forms of syphilitic manifestation are very often present in this polymorphic disease to give the clue to the real nature of the eruption.

In conclusion, the fact should be emphasized that there are cases of smallpox of so mild a character, with general symptoms so slight and eruption so sparse and ill-defined, as to make a positive diagnosis extremely difficult. It is a good plan to employ vaccination in such cases as a test. Within three or four days the experienced observer will be able to determine whether the vaccination is successful or not; a negative result will of course have but a moderate value, but a positive result will serve to definitely exclude the diagnosis of smallpox. In all cases of doubt, whether before or after the eruption has appeared, the physician owes it to himself not less than to the patient and the community to frankly explain to the patient or his family the difficulty in arriving at a diagnosis, and to express his suspicions that the case may be one of smallpox. It need hardly be said that such a case should be as strictly isolated as if the diagnosis of smallpox were already established.

CHAPTER III.

TREATMENT.

In the treatment of smallpox the therapeutic measures employed must necessarily vary with the severity of the disease and the condition of the patient in its successive stages. No remedy or plan of treatment will apply to all cases and at all times. As in the other exanthemata, there are cases of variola in which the disease runs so mild a course that a little nursing or simple attention to the personal comfort of the patient is all that is absolutely necessary. Such cases occur in those who have already had the disease,—for a second attack of smallpox must always be considered as a possibility, although it is a more rare occurrence than some writers would lead us to believe. Such cases also occur and with the greatest frequency in those who have been rendered more or less immune by a previous vaccination. But mild cases of smallpox may also occur among the unvaccinated; and in the present epidemic I have noted a few cases where, in spite of the lack of any protection from vaccination, the eruption and other symptoms of the disease were quite as mild as in some cases of so-called varioloid, or smallpox modified by previous vaccination.

In contrast with these cases which require no special medical treatment, there are others of marked severity with unexpected complications which tax the physician’s skill to its utmost capacity. Still another class of cases, fortunately rare in most epidemics, are those to which the name of variola maligna has been given, and in which medical treatment seems to be almost as unnecessary as in the mild cases, since all attempts to avert a fatal termination have so far proved utterly futile.

In the successive stages of a typical case of variola a marked change in the character of the treatment is demanded both by the peculiarities of the eruption and the accompanying general symptoms. Instead of considering the various types of variola from a therapeutic stand-point, therefore, it would seem more practical to discuss in their natural order those measures which are adapted to the successive stages of the disease, beginning with the

Period of Incubation.—During this period, which extends from the date of infection to the appearance of the earliest symptoms of the disease, treatment is rarely demanded, since in the great majority of cases the outbreak of the disease is a surprise, and in no case can it be positively known that a patient has smallpox until the initial symptoms appear, and often not until the characteristic eruption has developed. In many instances, however, it is quite certain that an individual has been exposed to the contagion of variola; and when such a one happens to be unvaccinated, or has not been vaccinated in recent years, the assumption is strong that the disease may have been contracted and will manifest itself in due time.

The question as to whether vaccination can have any notable effect in modifying the course of variola when performed after a person has been exposed to and has contracted the disease is one concerning which a considerable difference of