Smallpox, or VARIOLA, is one of the most formidable of the class of febrile diseases known as the Exanthemata (q.v.). The period of incubation (see under MEASLES) is generally twelve days.
All cases of regular smallpox are divisible into three stages—viz. (1) that of the initial or eruptive fever; (2) that of the progress and maturation of the specific eruption; and (3) that of the decline. The course of an ordinary case of discrete smallpox—i.e. one where the pocks remain throughout distinct from each other—will first be described, and afterwards the other forms will be discussed. The first stage begins with rigors, followed by heat and dryness of the skin, a quickened pulse, furred tongue, loss of appetite, pain in the pit of the stomach, with nausea, vomiting, headache, and often pains in the back and limbs. The violence of the pains in the back, and the obstinacy of the vomiting, are frequently very well marked and characteristic symptoms. In children the disease is often ushered in by convulsions; while delirium sometimes attends its onset in adults. On the third day minute red specks begin to come out—first on the face (where they are always most numerous), then on the neck and wrists, and on the trunk of the body, and lastly, on the lower extremities. These correspond to the incipient pocks, which can be felt like small shot under the skin, better, sometimes, than they can be seen. The fever, pain, sickness, &c. usually begin to subside as soon as the eruption appears, and by the beginning of the fifth day, when the eruption is generally fully out, and the second stage commences, have entirely disappeared. Upon the second or third day of the eruption a little clear lymph is seen in each pimple, which has increased considerably in size since its first appearance, and which is thus converted into a vesicle. The vesicles gradually increase in breadth, and their contents becoming more and more yellow and opaque, are converted into pustules. These are at first depressed in the centre, but at their fullest development often become turgid and hemispherical. The suppuration on the face is complete by about the ninth or tenth day from the commencement of the fever, and the same process rapidly follows in the other parts of the body in the same order of succession as that in which the eruption originally appeared. The progress of the pustules is usually accompanied by swelling of the skin of the face, with a painful sensation of heat and tension; the scalp is often swollen; soreness of the mouth from a modified eruption there is often present; and the patient exhales a peculiar and disagreeable odour. About the eighth or ninth day of the disease a recurrence of the fever, known as the fever of maturation, or secondary fever, sets in, with a return of headache, restlessness, and sometimes delirium. The third or declining stage is little more than a period of convalescence. About the eleventh or twelfth day the pustules on the face become brown and dry at the top, or some of them break, and the fluid which oozes out solidifies into a yellowing crust; and from this time the process of desiccation goes on, the swelling of the face subsides, and at last only dry scabs remain, which gradually fall off about the fifteenth or sixteenth day. It is not till three or four days after the scabs have formed on the face that the same process is completed over the whole body. The scabs are usually completely gone by the twenty-first day, leaving behind them blotches of a reddish-brown colour, which sometimes continue for some months before they quite disappear; and some of the pustules, in consequence of ulceration of the true skin, may leave pits, especially on the face, which remain permanently. The period of scabbing is accompanied by various symptoms of improvement: the tongue becomes clean, the appetite returns, and by the time that the scabs have fallen off the patient may be regarded as restored to health; so that the entire course of a case of discrete smallpox occupies about three weeks.
Generally speaking, the severity of the disease is proportional to the number of pocks; and when these are so numerous as to run together on any part of the body, the disease is said to be confluent. This form differs in many important respects from that already described. The eruption is necessarily modified: the individual pocks are smaller, but by their coalescence they give the skin of the face an appearance 'like a mask of parchment,' and generally lead to much more scarring of the skin. Severe laryngitis and bronchitis, and ulceration of the cornea, with consequent impairment or destruction of sight, are of frequent occurrence; and salivation is a usual symptom. But most important of all is the difference in the course of the fever. The remission described above in the first stage is slight, if it occurs at all; and the secondary fever, although on this account less conspicuous, is more severe, and much more dangerous to life.
Malignant smallpox is characterised by the severity of the onset, but particularly by the occurrence during the first few days of hæmorrhages under the skin, and from the various orifices of the body. Such cases are almost without exception rapidly fatal, sometimes so early that no sign of the characteristic eruption appears at all.
Modified smallpox, sometimes (but not happily) called varioloid, is the name applied to cases of the disease in which the eruption runs a less severe course than usual. They may be at first discrete or confluent; but the pocks abort either at the papular or the vesicular stage, or if they become pustular are small, and dry up with unusual rapidity. The constitutional symptoms are correspondingly less marked. This form of the disease with rare exceptions occurs only in those who have been vaccinated, or have had a previous attack of smallpox. The form of the disease which follows Inoculation (q.v.) has a shorter incubation period (usually ten days), and a shorter and milder course; and the mortality is very much less than when it is contracted by infection.
The cause of smallpox is universally allowed to be a specific contagion, of whose nature we are in the most profound ignorance. There is probably no disease so contagious as this. Dr Haygarth stated (in 1793) that, during his long attention to this subject, not a single instance had occurred to prove that persons liable to smallpox could associate in the same chamber with a patient in the distemper without receiving the infection. The contagion acts either through the air, or by contact with the skin, or by inoculation; and the disease may be caused by the dead body, even when it has not been touched. What products of the diseased body are contagious is not exactly known, but the contents of the pustules and the dried scabs certainly are so. Opinions are divided as to the period at which the disease begins and ceases to be contagious. It is safest to maintain that it is capable of self-propagation as soon as the febrile symptoms have exhibited themselves. How soon the patient ceases to be dangerous cannot be decided with accuracy; but the stability of the contagious principle may be inferred from the fact that clothing will retain it for months, and it is said for years, when confined. Like all the contagious exanthemata, smallpox appears in an epidemic form, at irregular and, in our ignorance, it would almost seem capricious intervals. After an extraordinary exemption, perhaps for years, a district is suddenly invaded by it, and continues to suffer for a longer or shorter period, after which the disease spontaneously disappears—dies out, as it were—and does not reappear perhaps for years. Different epidemics vary very much in their severity, and isolated cases are usually milder than those occurring when the disease is epidemic. Race has much to do with the severity of the disease; the constitution of the dark races, especially the Negro, being singularly susceptible of the contagion, and exhibiting very little power of resisting the fatal tendency of the disease.
It is generally admitted that the discovery of Vaccination (q.v.), by which smallpox is deprived of its danger, is the greatest triumph of modern medicine. Inoculation (q.v.) protected the individual, but, by spreading the disease, increased rather than diminished the total number of deaths, while vaccination has the advantage of protecting both the individual and the community.
With regard to prognosis, it may be stated generally, it is a very fatal, and was formerly an extremely destructive disease—one death occurring in every four or five cases. Modified smallpox is very seldom fatal, although instances of death are occasionally reported. Smallpox is more fatal at the two extremes of life than in the intervening period, and is especially dangerous in pregnancy. In olden times it was believed that the eruption was an effort of nature to get rid of the noxious matter, and hence heating and stimulating measures were adopted with the view of promoting the eruption. To Sydenham belongs the credit of first recommending an entirely opposite or cooling mode of treatment; but his suggestions met with the most strenuous opposition, and it was not till long after his death that the cooling treatment was fairly established. In mild cases, and in cases of modified smallpox, the physician has merely to guard the patient against hurtful influences, such as stimulating foods or drinks, too hot a room, or improper exposure to cold, and to prescribe cooling drinks during the fever, and occasional laxatives if they shall be required. In more severe cases the fever may be combatted by saline purgatives, prescribed so as to produce two or three liquid stools daily, and by free ventilation of the surface of the body. When the eruption is all out, if the pimples on the face are few and distinct the danger may be regarded as over, and no further treatment is required. If, however, the disease assume a confluent form, wakefulness and restlessness are apt to come on about the eighth day, and opiates in free doses may be prescribed with benefit. If the pustules are abnormally torpid in reaching their maturity, it may be expedient to administer strong broths, or even wine; and when the pustules are livid, and intermixed with Petechiæ (q.v.), bark and acids must be additionally ordered, although the patient is then too often beyond the reach of help. During the secondary fever the bowels must be kept gently open, and opiates should be prescribed once or twice each day. A more nourishing diet is now called for, and wine should be given if the pulse is very weak. The external itching is partly relieved by the opiates, but local applications are also employed: cold cream, or a mixture of equal parts of olive-oil and line-water, may be thus used with advantage. Numerous special methods have been devised for the purpose of preventing the pitting or seaming of the face, which is often a hideous permanent disfigurement to the patient, but there is not yet sufficient evidence that any of them is uniformly satisfactory in its results.
During the period of desquamation an occasional warm bath may be prescribed with advantage; and the patient should always resort to this measure, as a precaution against carrying the contagion about with him, before again mixing in society.
The history of this remarkable disease is clothed in considerable obscurity. Its original habitat is quite uncertain; but there seems no doubt that it has been prevalent in India from a remote period, and in China since at least 200 years before the
Christian era. It has been conjectured that it was one of the pestilences which occurred in Europe during the first and second centuries after that era; but the first accurate description of it is that of Rhazes, an Arabian physician, who flourished early in the 10th century. It appears to have reached England towards the close of the 9th century. After the Crusades it prevailed in most of the temperate countries of Europe, but did not reach the northern countries of Norway, Lapland, &c. for some time later. In 1517 it was carried from Europe to St Domingo; and three years later it reached Mexico, where it committed fearful devastations, and whence it spread with intense virulence throughout the New World. (According to Robertson, three millions and a half of people were destroyed in Mexico alone.) In 1707 it was introduced into Iceland, when more than a fourth part of the whole population fell victims to it; and it reached Greenland still later (1733), when it spread so fatally as almost to depopulate the country. These cases are striking illustrations of the law that seems universally true, that a contagious disease is always most virulent on its first introduction to a new scene of action. At the present day the interior of Africa, and especially the upper basin of the Nile, seems to be the region where smallpox is most destructive. In Europe it is constantly present in most of the large cities; but during the 19th century—i.e. since the introduction of vaccination—epidemics have been much less frequent and severe than before. The most intense and wide-spread was that of 1869–73 (see Report of Medical Officer of the Privy-council, 1874). Smallpox seems first to have been called by that name in the 15th century; pockes or pox (a contracted plural of pock) having come to be loosely used for several eruptive diseases, and especially for ‘French pox’ or syphilis. Till Sydenham’s time measles and scarlet fever were frequently confounded with smallpox.