There is still another class of cases of variola which have been properly called malignant. These cases are character ized by extreme depression of all vital functions from the initial chill to the end. The patient suddenly becomes cold, with blueness or leaden hue of the surface; a very frequent, variable, and weak pulse; shallow and hurried breath ing; intense pain in the loins, head, and epigastrium, with frequent retching or efforts to vomit, and constant delirium or stupor. With the febrile reaction all the symptoms named, except the cold ness, are increased, and during the sec ond day the urine is very scanty or sup pressed; the matter vomited, bluish or dark color, with streaks of blood; ery thematous or purplish spots appear on different parts of the surface, or, instead, the whole surface becomes covered with an exanthcmatous rash, with here and there a petechial spot. During the third day the anomalous spots, whether cry thematons or begin to disappear, and the true, pointed papules of variola begin to appear; and by the following morning the entire cutaneous surface is thickly studded with them; many of them infiltrated with blood at their base, giving them a blackish ap pearance. But the appearance of the variolous eruption is accompanied by no subsidence of fever or general improve ment, as in milder cases. On the con trary, the pulse becomes more rapid and feeble, the respirations irregular and inefficient, intestines discharge involun tarily, and renal secretion suppressed, and death follows generally between the third and sixth day of the disease. In all the severe grades of variola, during the suppurative stage and the subsequent desiccation, a very disagreeable and pe culiar odor emanates from the body of the patient, making strict attention to ventilation and the use of disinfectives necessary. In the cases with numerous pustules in the mouth and faeces there is much flow of saliva, more or less pain ful deglutition, with some tendency to bronchopneumonia or oedema of the glottis, especially near the completion of the suppurative stage.
Diagnosis.—An abrupt attack of act ive fever without previous feelings of indisposition, and characterized by suf fused redness of the face and neck and intense pain in the loins, should suggest to the mind of the physician the possi bility of an attack of variola. There is not, however, any positively diagnostic symptom of this disease until the ap pearance of the characteristic eruption, usually on the fourth day. The positive elevation and hardness of each papule constituting the eruption readily dis tinguishes it from any of the exanthem atous fevers, while the minute vesicle on the apex of the hard papule equally distinguishes it from the larger vesicles without any hard base of varicella. The absence of cough and notable catarrhal symptoms farther separates it from rubeola.
When the variolous vesicles have pro gressed far enough to show the distinct umbilicated depression in the centre their diagnostic features are complete. Bacteriologists have thus far been un able to find any microbe distinctively as sociated with this disease.
Etiology. — The specific or essential cause of variola is a contagium generated in the body of the sick sufficient to im pregnate the blood, the secretions, and the exhalations, and to render the air surrounding the patient contagious. As the disease progresses the contagion ac cumulates in the serum and purulent matter of the pustules, and remains active in the dry scabs and adheres to clothing. If such scabs or infected, clothing are freely exposed to fresh air, the activity of the contagium gradually diminishes until it is lost; but if they are kept in vessels or closely packed trunks or boxes they may be carried from one country to another and preserve their contagiousness a long period of time. The etiological element of variola has recently been traced to a parasite by Councilman, but the investigations are as vet unfinished.
Pathology.—When a portion of the specific contagium or poison of variola is received into the living body susceptible to its action, it requires a period of from nine to fourteen days to multiply or de velop sufficient to cause any disturbance or manifestation of its presence. When this period of incubation is completed the contagium rapidly develops an active irritative action on both nervous and vascular structures and thereby estab lishes a general fever of greater or less intensity. The contagium, however, by its manifest affinity for the cutaneous tissue and the mucous membrane of the mouth and fauces, rapidly finds ment therein to such an extent that, in a large majority of cases, the blood in from three to four days is so far relieved of its presence that all the active febrile symptoms have disappeared. But at the same time the virus at each point of its deposit in the cutis vera starts a local inflammation that presents the form of a hard elevation or papule with a minute vesicle on its apex, and goes through the subsequent stages already described under the head of symptoms. If the contagium evolved during the period of incubation is so large that it fails to find complete lodgment in the cutaneous surface, or from any other cause is re tained in the blood, the fever does not subside with the appearance of the erup tion, the blood rapidly undergoes oration, and the case soon presents a ma lignant aspect and death generally fol lows. The nature of the pathological changes produced by one impression of the variolous contagium on the human system is such that one attack of the dis ease renders the individual permanently immune to subsequent attacks. In a small percentage of the eases the munity diminishes, and after several years the system again becomes susceptible to the contagium; but the second attack is generally milder and of shorter duration. Such second and modified eases have been termed vario loid, and seldom terminate fatally. But they evolve the genuine variolous eon tagium, and consequently communicate unmodified variola to persons not previously protected.