VARIOLOID is that form of variola in which the disease is modified, either in its course, duration, or intensity of symptoms, such modification usually resulting, directly or indirectly, from the protective influence of vaccination or from a previous attack of variola.
The symptoms of the class of patients commonly regarded as suffering from varioloid are all those of variola, modified, however, in the direction of a mitigation of their intensity and dangerous character. It is thus evident that there is no strict line of demarcation between the very mildest physical expression of the variolous poison and that variola vera which presents atypically benign symptoms in any stage of its career. Within this wide range of possibilities cases of varioloid occur which certainly differ from each other by very marked degrees.
The invasion stage of varioloid may be shorter or longer than that occurring in variola vera, and may be insignificant or intensely marked as regards the severity of its symptoms. According to Bartholow4 the invasion rashes are here of common occurrence; and the more extensive the latter, the less copious the subsequent eruption. It must be admitted that a personal experience has not confirmed us in this view.
4 Loc. cit.
After the high fever and severe cephalic and lumbar pains of this stage there may follow, in the case of varioloid, a complete defervescence and the appearance of a very copious exanthem. With this, however, the apogee of the disease may be reached, and the subsequent symptoms be altogether insufficient in comparison with those which have preceded. Thus, the maculo-papules may never reach a vesicular stage, or, having attained this, the vesicles may not be umbilicated, or may shrivel after their contents have assumed a lactescent color, and be succeeded by light superficial crusts which in a few days fall. Or, again, the pustular stage of the lesions may be fully developed, even with the production of a halo about the pocks, while yet there is no swelling of the skin and but trifling subjective sensations experienced by the patient. The pustules in the course of from four days to a week desiccate and are shed, leaving behind them violaceous pigmentations of the surface without persistent cicatricial sequelæ.
Other cases, again, instead of producing the impression upon an observer of being illustrations of a malady aborted or cut short at some period of its career, seem to exhibit merely a modification in the intensity or distribution of symptoms betrayed in a wellnigh typical career. Thus, there may be a total absence or insignificant reminder of the septic fever usually known as the secondary fever of variola, and the elements of the eruption may be few or appear in scanty number upon the face and more copiously elsewhere. The latter may, however, pursue a perfectly typical career and be followed by characteristic scars.
There is yet another type of varioloid with which many practitioners become familiar who have experience in epidemics of small-pox. The patient exhibits distinct symptoms of malaise in the period of incubation. The fever of invasion, with its characteristic pains and nausea, is equally well marked. Defervescence occurs with a trifling eruption of maculo-papules, which in two days have wellnigh completely disappeared. There is no secondary fever, but the patient is far from well. There is a period of anæmia, mental depression, marked languor, and unmistakable evidences of physical prostration out of all proportion to the precedent symptoms. In these cases it may well be believed that the poison has at last produced a strong impression upon the nervous centres. The most characteristic feature of these cases is the tedious convalescence from an apparently trifling form of the malady.
The identity of varioloid with variola is abundantly shown—first, by the occurrence of intermediate forms of every grade, from the mildest evidence of variolous poisoning to typically developed cases of variola vera; second, by the fact that patients affected with varioloid are capable of transmitting variola to the unprotected; third, by the anatomico-pathological fact that the structure of the pock, when it appears, is the same in all.
A variation as to the form and contents of the lesion of modified variola occasionally occurs as a consequence of individual peculiarities or of the special surroundings of the patient. A number of useless terms have been employed to designate these peculiarities, the most of which are relics of the superstitions of the past. In variola siliquosa the pocks are said to contain air only; in v. pemphicosa, bullous lesions predominate; in v. verrucosa, the papules, after partial evolution and involution, leave minute wart-like papillary masses upon the face; in v. crystallina, there are superficial vesicles only filled with clear serum, which somewhat resemble those recognized as sudamina. The older English writers with as little reason described cases of horn-pox, swine-pox, etc., differing only from those of variola by the anomalous behavior of the exanthem in the course of its evolution.5
5 Besides the terms given above, Hebra gives the following list of Latin adjectives which have been employed to describe special varieties of small-pox, none of which requires special explanation: variola papulosa, conica, acuminata, globosa, globulosa, tuberculosa, cornea, fimbriata, miliaris, lymphatica, vesiculosa, pustularis, rosea, morbillosa, carbunculosa, etc.