1911 Encyclopædia Britannica/Smallpox

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SMALLPOX, or Variola (varus, " a pimple "), an acute infectious disease characterized by fever and by the appearance on the surface of the body of an eruption, which, after passing through various stages, dries up, leaving more or less distinct cicatrices. (For pathology see Parasitic Diseases.) Few diseases have been so destructive to human life as smallpox, and it has ever been regarded with horror alike from its fatality, its loathsome accompaniments and disfiguring effects, and from the fact that no age and condition of life are exempt from liability to its occurrence. Although in most civilized countries its ravages have been greatly limited by the protection afforded by vaccination, yet epidemic outbreaks are far from uncommon, affecting especially those who are unprotected, or whose protection has become weakened by lapse of time.

Much obscurity surrounds the early history of smallpox. It appears to have been imported into Europe from Asia, where it had been known and recognized from remote antiquity. The earliest accounts of its existence reach back to the middle and end of the 6th century, when it was described by Procopius and Gregory of Tours as occurring in epidemic form in Arabia, Egypt and the south of Europe. In one of the narratives of the expedition of the Abyssinians against Mecca (c. 550) the usual miraculous details are combined with a notice of smallpox breaking out among the invaders.[1] Not a few authorities, however, regard these accounts as referring not to smallpox, but to plague. The most trustworthy statements as to the early existence of the disease are found in an account by the 9th-century Arabian physician Rhazes, by whom its symptoms were clearly described, its pathology explained by a humoral or fermentation theory, and directions given for its treatment. During the period of the Crusades smallpox appears to have spread extensively through Europe, and hospitals for its treatment were erected in many countries. But at this period and for centuries afterwards the references to the subject include in all likelihood other diseases, no precise distinction being made between the different forms of eruptive fever. Smallpox was known in England as early as the 13th century, and had probably existed there before. It appears to have been introduced into America by the Spaniards in the early 16th century, and there, as in Europe and throughout the known world, epidemics were of frequent occurrence during succeeding centuries.

The only known factor in the origin of smallpox is contagion—this malady being probably the most contagious of all diseases. Its outbreak in epidemic form in a locality may frequently be traced to the introduction of a single case from a distance. The most direct means of communicating smallpox is inoculation. By far the most common cause of conveyance of the disease, however, is contact with the persons or the immediate surroundings of those already affected. The atmosphere around a smallpox patient is charged with the products of the disease, which likewise cling to clothing, furniture &c. The disease is probably communicable from its earliest manifestations onwards to its close, but it is generally held that the most infectious period extends from the appearance of the eruption till the drying up of the pustules. Smallpox may also readily be communicated by the bodies of those who have died from its effects. No age is exempt from susceptibility to smallpox. Infants are occasionally born with the eruption or its marks upon their bodies, proving that they had undergone the disease in utero. Dark-skinned races are said to suffer more readily and severely than whites. One attack of smallpox as a rule confers immunity from any recurrence, but there are numerous exceptions to this rule. Overcrowding and all insanitary surroundings favour the spread of smallpox where it has broken out ; but the most influential condition of all is the amount of protection afforded to a community by previous attacks and by vaccination (q.v.). Such protection, although for a time most effectual, tends to become exhausted unless renewed. Hence in a large population there is always likely to be an increasing number of individuals who have become susceptible to smallpox. This probably explains its occasional and even apparently periodic epidemic outbreaks in large centres, and the well-known fact that the most severe cases occur at the beginning—those least protected being necessarily more liable to be first and most seriously attacked.

Symptoms.—While the symptoms of smallpox are essentially the same in character in all cases, they are variously modified according to the form which the disease may assume, there being certain well-marked varieties of this as of most other infectious maladies. The following description applies to an average case. After the reception into the system of the smallpox contagion the onset of the symptoms is preceded by a period of incubation, during which the patient may or may not complain. This period is believed to be from about ten to fourteen days. In cases of direct inoculation of the virus it is considerably shorter. The invasion of the symptoms is sudden and severe, in the form of a rigor followed by fever (the primary fever) , in which the temperature rises to 103º or 104º Fahr. or higher, notwithstanding that perspiration may be going on. A quick pulse is present, together with thirst and constipation, while intense headache accompanied with vomiting and pain in the back is among the most characteristic of the initial symptoms. Occasionally the disease is ushered in by convulsions. These symptoms continue with greater or less intensity throughout two entire days, and during their course there may occasionally be noticed on various parts of the body, especially on the lower part of the abdomen and inner sides of the thighs, a diffuse redness accompanied by slight spots of extravasation (petechiae), the appearance somewhat resembling that of scarlet fever. These " prodromal rashes," as they are termed, appear to be more frequent in some epidemics than in others, and they do not seem to have any special significance. They are probably more frequently seen in cases of the mildest form of smallpox (formerly termed varioloid), referred to below as modified smallpox. On the third day the characteristic eruption begins to make its appearance. It is almost always first seen on the face, particularly about the forehead and roots of the hair, in the form of a general redness; but upon this surface there may be felt by the finger numerous elevated points more or less thickly set together. The eruption, which is accompanied by heat and itching, spreads over the face, trunk and extremities in the course of a few hours—continuing, however, to come out more abundantly for one or two days. It is always most marked on the exposed parts; but in such a case as that now described the individual " pocks " are separated from each other (discrete). On the second or third day after its appearance the eruption undergoes a change—the pocks becoming vesicles filled with a clear fluid. These vesicles attain to about the size of a pea, and in their centre there is a slight depression, giving the characteristic umbilicated appearance to the pock. The clear contents of these vesicles gradually become turbid, and by the eighth or ninth day they are changed into pustules containing yellow matter, while at the same time they increase still further in size and lose the central depression. Accompanying this change there are great surrounding inflammation and swelling of the skin, which, where the eruption is thickly set, produce much disfigurement and render the features unrecognizable, while the affected parts emit an offensive odour, particularly if, as often happens, the pustules break. The eruption is present not only on the skin, but on mucous membranes, that of the mouth and throat being affected at an early period; and the swelling produced here is not only a source of great discomfort, but even of danger, from the obstruction thus occasioned in the upper portion of the air-passages. The voice is hoarse and a copious flow of saliva comes from the mouth. The mucous membrane of the nostrils is similarly affected, while that of the eyes may also be involved, to the danger of permanent impairment of sight. The febrile symptoms which ushered in the disease undergo marked abatement on the appearance of the eruption on the third day, but on the eighth or ninth, when the vesicles become converted into pustules, there is a return of the fever (secondary or suppurative fever), often to a severe extent, and not infrequently accompanied by prominent nervous phenomena, such as great restlessness, delirium or coma. On the eleventh or twelfth day the pustules show signs of drying up (desiccation), and along with this the febrile symptoms decline. Great itching of the skin attends this stage. The scabs produced by the dried pustules gradually fall off and a reddish brown spot remains, which, according to the depth of skin involved in the disease, leaves a permanent white depressed scar—this " pitting " so characteristic of smallpox being specially marked on the face. Convalescence in this form of the disease is as a rule uninterrupted.

Varieties.—There are certain varieties of smallpox depending upon the form it assumes or the intensity of the symptoms. Confluent smallpox (variola confluens), while essentially the same in its general characters as the form already described, differs from it in the much greater severity of all the symptoms even from the onset, and particularly in regard to the eruption, which, instead of showing itself in isolated pocks, appears in large patches run together, giving a blistered aspect to the affected skin. This confluent condition is almost entirely confined to the face, and produces shocking disfigurement, while subsequently deep scars remain and the hair may be lost. The mucous membranes suffer in a similar degree of severity, and dangerous complications may arise from the presence of the disease in the mouth, throat and eyes. Both the primary and secondary fevers are extremely severe. The mortality is very high, and it is generally estimated that at least 50% of such cases prove fatal, either from the violence of the disease or from one or other of the numerous complications which are specially apt to attend upon it. Convalescence is apt to be slow and interrupted. Another variety is that in which the eruption assumes the haemorrhagic form owing to bleeding taking place into the pocks after their formation. This is apt to be accompanied with haemorrhages from various mucous surfaces (particularly in the case of females), occasionally to a dangerous degree and with symptoms of great prostration. Many of such cases prove fatal. A still more serious form is that termed malignant, toxic or purpuric smallpox, in which there is intense streptococcus septicaemia, and the patient is from the onset overwhelmed with the poison and quickly succumbs—the rash scarcely, if at all, appearing or showing the haemorrhagic or purpuric character. Such cases are, however, comparatively rare. The term modified smallpox is applied to cases occurring in persons constitutionally but little susceptible to the disease, or in whom the protective influence of vaccination or a previous attack of smallpox still to some extent exists. Cases of this mild kind are of very common occurrence where vaccination has been systematically carried out. As compared with an average case of the unmodified disease as above described this form is very marked, the differences extending to all the phenomena of the disease. (1) As regards its onset, the initial fever is much milder and the premonitory symptoms altogether less in severity. (2) As regards the eruption, the number of pocks is smaller, often only a few and mostly upon the body. They not infrequently abort before reaching the stage of suppuration: but should they proceed to this stage the secondary fever is extremely slight or even absent. There is little or no pitting. (3) As regards complications and injurious results, these are rarely seen and the risk to life is insignificant.

Various circumstances affect the mortality in ordinary smallpox and increase the dangers attendant upon it. The character of the epidemic has an important influence. In some outbreaks the type of the disease is much more severe than in others, and the mortality consequently greater.

In 1901 and 1903 there were epidemics in the United States in which it was only 2%. The mortality in the Philadelphia epidemic is given by Welch and Schamberg as 26–89% in 7204 cases, while in the Glasgow epidemic of 1900–1901, it reached 51.6% in the unvaccinated and 10.4% in the vaccinated. Below are some particulars of the annual death rate.

Smallpox Death Rate, England and Wales.
Years. Number of
Deaths from
Deaths from
to every
Million living.




  • Deaths entered as being from chicken-pox are not included, though many are probably due to the graver disease.

Smallpox is most fatal at the extremes of life, except in the case of vaccinated infants, in whom there is immunity from the disease. Again, any ordinary case with discrete eruption is serious, and a case of confluent or even semi-confluent character is much more grave, while the haemorrhagic variety is frequently, and the toxic always, fatal. Numerous and often dangerous complications, although liable to arise in all cases, are more apt to occur in the severer forms, and in general at or after the supervention of the secondary fever. The most important are inflammatory affections of the respiratory organs, such as bronchitis, pleurisy or pneumonia, diphtheritic conditions of the throat, and swelling of the mucous membrane of the larynx and trachea. Destructive ulceration affecting the eyes or ears is a well- known and formidable danger, while various affections of the skin, in the form of erysipelas, abscess or carbuncles, are of not infrequent occurrence.

The prophylaxis of smallpox depends on successful vaccination and re-vaccination (see Vaccination), together with the establishment of smallpox hospitals for the treatment of the disease when it has broken out, to which the patient should be at once removed, and those who have been in contact with the patient should be promptly re-vaccinated. The efficiency of the protection given by vaccination and systematic re-vaccination is demonstrated by the almost entire suppression of the disease in Germany (see Dr Bruce Low's Report to the Local Government Board, Prophylaxis and
1903–1904). Mrs Garrett Anderson,writing to The Times in September 1903, showed the enormous expense laid on the rates in England for the maintenance of smallpox hospitals in order to counteract inefficient vaccination. London with a population of 6½ millions reserves 2500 beds in a hospital removed from the city; Berlin with a population of 2 millions reserves 12 beds in the pavilion of a general hospital; Dresden with a population of 500,000 reserves 20 beds in the Friedrichstadt Hospital, but no case was admitted for 10 years previous to the Report. In Stuttgart (population 200,000) a hut of six beds is set aside for smallpox, but it has fallen into bad repair from disuse. Smallpox cases in Germany are usually sporadic cases introduced by foreigners. Where persons have been exposed to the infection of smallpox, if immediate vaccination fails to protect them from the disease, it has been shown to considerably modify the type. The plan of identification and surveillance of all contact cases has given good results. In the Bristol epidemic of 1908 there were 35 cases and 9 deaths. The contacts numbered 1354, and 16,398 visits of inspection were paid.

The patient should lie on a soft bed in a well-ventilated but somewhat darkened room and be fed with the lighter forms of nutriment, such as milk, soups, &c. The skin should be sponged occasionally with tepid water, and the mouth and throat washed with an antiseptic solution. In a severe case, with evidence of much prostration, stimulants may be advantageously employed. The patient should be always carefully watched, and special vigilance is called for where delirium exists. This symptom may sometimes be lessened by sedatives, such as opium, bromides or chloral. With the view of preventing pitting many applications have been proposed, but probably the best are cold or tepid compresses of light weight kept constantly applied over the face and eyes. The water out of which these are wrung may be a weak solution of carbolic or boracic acid. When the pustules have dried up the itching this produces may be much relieved by the application of oil or vaseline.

What is known as the red light treatment, in which the actinic or chemical rays are excluded, has been advocated by Prof. Niels Finsen of Copenhagen and others. He considers it valuable only in that it protects the pustule from the deleterious effects of light, and he and other observers claim that if resorted to early it abolishes suppuration in the pustules, lessens scarring and shortens the course of the disease. Medical opinion in England is divided as to its merit. Herbert Peck of Chesterfield, in 244 cases so treated in 1902–1905, had only 6 deaths, a mortality of 2.4%, while the case mortality during the same period was, Lancashire 5.8%, Derbyshire 6%, Cheshire 6.4%, Liverpool 2.7% and Manchester 5.6% in cases treated without red light. An interesting fact in connection with the treatment is its great antiquity in China and Japan, while in England in the middle ages smallpox patients wore red garments and lay in beds where the light filtered through red curtains.

Complications are to be dealt with as they arise, and the severer forms of the disease treated in reference to the special symptoms presented. In cases where the eruption is tardy of appearing and the attack threatens to assume the toxic form, marked benefit attends the use of the wet pack. Disinfectants should be abundantly employed in the room and its vicinity, and all clothing, &c, in contact with the patient should be exposed to the vapour of formalin. Béclère, Thomson and Brownlee have advocated the use of the serum of immunized heifers. The dose, however, requires to be very large, being equivalent to one-fiftieth part of the body weight in adults and one-twentieth part in children.

Inoculation.—Previously to the introduction of vaccination (q.v.) the method of preventive treatment by what was known as inoculation had been employed. This consisted in introducing into the system—in a similar way to the method now commonly employed in vaccination—the smallpox virus from a mild case with the view of reproducing the disease also in a mild form in the person inoculated, and thus affording him protection from further attack. This plan had apparently been resorted to by Eastern nations from an early period in the histoty of the disease. During the latter part of the Ming dynasty there was introduced into China a system of inoculation in which the method was to blow the pulverized germ-laden crusts from a small-pox pustule through a silver tube into the nostril, the left being chosen in a male, the right in a female. Inoculation was known tp be extensively practised in Turkey in the beginning of the 18th century, when, chiefly through the letters of Lady Mary Wortley Montagu, it became known and was speedily adopted in England. There is no doubt, both from the statistics of the Smallpox and Inoculation Hospital, London, and from the testimony of physicians throughout the country, that this practice made a marked impression upon the fatality of the disease, and was itself attended with extremely little risk to life. The objections to it, howeyer, were great, for, although usually conveying the smallpox in a mild form, it not infrequently took effect severely, and, while death might be averted, the disfiguring results of the disease remained. Further, each inoculated person upon whom the operation took effect became for the time being a possible source of infection to others, and in point of fact the practice tended to spread the disease and so to increase the general mortality. Although inoculation continued to be practised for a number of years subsequently to Jenner's great discovery, it gradually became displaced by vaccination, and in 1840 an Act of Parliament was passed rendering smallpox inoculation unlawful in England.

  1. See Nöldeke, Geschichte der Perser . . . aus Tabari (Leiden, 1879), p. 218. Nöldeke thinks that this notice may be taken from genuine historical tradition, and seems to find an allusion to it in an old poem.