Smallpdx or Variola

Varieties.

When the pocks are separated from each other, with clear spaces between, the disease is called discrete or distinct smallpox; when the pocks run together, confluent smallpox. There are two forms of haemorrhagic smallpox: 1, always fatal when haemorrhage into the skin and mucous membranes occur (Purpura variolosa, black smallpox) ; 2, benign when the haemor rhage takes place inside the pustule (Variola hemorrhagica pus tulasa).

Recent Investigations.

Since about 1910 much knowledge of the nature of this disease has accrued in the course of attempts to discover the causal organism. This has been sought, though fruitlessly, in many direct investigations of the rash and of the blood by microscopical examination and by attempts to inoculate animals. The failure is explained, in part, by the discovery that the virus of vaccinia and smallpox belong to the group of filter passing viruses (see FILTER-PASSING VIRUSES). Considerable in terest centres around the discovery of the so called Cytoryctes variolae and vaccine described by Guarnieri in 1892. Jenner be lieved that cowpox (vaccinia) and smallpox (variola) have the same origin and nature. But attempts to inoculate the cow with smallpox matter failed and Jenner's opinion was not substantiated until Monckton Copeman and others proved that the virus of smallpox can be inoculated in the cow by a process of transmission or passage and that in the cow, under these conditions, typical lesions of vaccinia are produced. But although vaccinia is the same disease as smallpox, during its passage through the cow it has lost the power of producing bacteriemia in man though it induces the typical lesion at the site of inoculation and by means of this local lesion, protects the vaccinated individual against the major infection from which the vaccine matter was derived.

Establishment of the homologous relationship between variola and vaccinia widened the field of investigators into the nature of the contagium of smallpox by providing a material, viz., vac cine lymph, which is at once abundant and easily produced. By experiments on the rabbit, which is susceptible to vaccinia, the im munity conferred by vaccinia has been studied and it has been shown that specific antibodies are produced in the blood and tis sues of the vaccinated animal similar to those produced in ty phoid fever and cholera, and that the antibodies in vaccinia and variola are apparently identical. It has been claimed, though on insufficient grounds, that this identity affords a means of certain diagnosis of the disease in doubtful cases of smallpox.

Serum Therapy.

In so far as the therapeutic application of the knowledge thus acquired is concerned, it has been shown that the serum of animals immune to vaccinia not only has protective power against vaccinia but also is possessed of curative properties because it destroys the virus of vaccinia in vitro. Whether this

curative property is susceptible of increase by means of a gradu ated increase of dose of virus has not been investigated. In France, the serum of convalescent smallpox patients has been used in treatment and it is claimed that an undoubted curative result was obtained in cases which from clinical experience would almost certainly have proved fatal. But so far the virus of smallpox has not been obtained in quantity sufficient to permit of the attempt to manufacture a therapeutic serum, nor has it been shown that the immunity of an animal to vaccinia can be raised to a degree which might make its serum of value in the treatment of smallpox.

Polyvalent vaccines and serum prepared from pyogenic organ isms have been used with some success in the treatment of severe confluent smallpox. This treatment is based on the assumption that the severity of the later stage of the illness in confluent smallpox, i.e., the stage of maturation or pustulation of the rash with the secondary fever of the disease, is closely associated with a secondary pyogenic infection.

Incidence in Europe During Recent Years.

The mode of spread of smallpox may be illustrated by a short account of the incidence of the disease in Europe from 1910 to 1924. It is convenient to divide the period into three quinquennia 1910-4, the period preceding the World War; 2. 1915-9, the period of the War; 3. 1920-4, the period of gradual recovery from the War.

During the first quinquennium no satisfactory arrangement existed among the European powers for the interchange of infor mation concerning the incidence of epidemic diseases, and par ticularly from large areas where the disease is endemic and vaccination negligible, such as Spain, the Balkan States, Turkey and Russia, information concerning the rise and fall in incidence or even of serious epidemic extensions of the disease was scanty and unreliable. During this quinquennium the disease was very prevalent in Italy where a severe epidemic occurred in 1911-2. On the other hand, in France, Belgium, Austria, Germany, Den mark, Holland and the Scandinavian countries, smallpox was a rare disease as it had been since the beginning of the century. In England and Wales no extensive epidemic had occurred since the outbreak of 1902-3-4 and in the five years' period before the War only 88 deaths from smallpox were recorded in Great Britain.