The prognosis is generally favourable. The disease runs its course within relatively fixed periods, according to the development of the pustules, and recovery occurs without complications.
Treatment. No curative treatment can be laid down, the development of the disease being perfectly regular and tending to recovery. Simple hygienic precautions and cleanliness are sufficient to avoid complications due to suppuration.
COW-POX AND HUMAN VARIOLA—PREPARATION OF VACCINE.
Time and experience having proved that inoculation with cow-pox or vaccinia protected human beings against small-pox, the question arose as to the connection between the two diseases, whether or not they were identical and whether vaccinia in the bovine animal might not merely represent an alternative form of small-pox. The importance of the question will at once be understood by bearing in mind the danger to which human beings would be exposed by vaccination with small-pox virus unmodified by passage through the calf.
Nevertheless, at the present time the opinion of the early writers appears to prevail, and the theory of identity is accepted by the great majority of scientific men. The reason why experimenters in the second group came to believe in duality is that the method of inoculation chosen (by puncture) was not entirely reliable. The inoculations proved too slight, and it is only after inoculation by scarification or incision that typical eruptions can be reproduced in series.
Preparation of vaccine. Whether cow-pox and small-pox are or are not identical, the benefits resulting from vaccination are none the less real, and it is to be hoped that vaccination and revaccination will soon be made obligatory in all countries. We should then no longer have to deplore those epidemics of small-pox which periodically cause consternation in large cities and colonies.
The preparation of vaccine has been the subject of such minute care in every country that neglect of vaccination is astonishing. The material is obtained from calves or cows. In France the vaccine is prepared from animals of five to eight months old, free from disease. The old system of inoculation by puncture has been completely abandoned, the yield being insufficient, scarifications or incisions being now employed.
The animal is secured or, better still, laid down on a suitable table, and is shaven over a sufficient surface. The inoculations are made on the sides of the chest, over the thorax or elsewhere, but preferably over the flank and thorax, as being most readily accessible. The region of operation is rendered aseptic as far as possible, and scarified in lines about 1 to 2 inches in length, the lines of one horizontal row alternating with those in the next. It is imperative that the slight bleeding which may result should entirely cease before inoculation is attempted.
The scratches are inoculated with the purest vaccine obtainable, preferably with glycerinated pulp which has been kept for six weeks or two months. From the third day the lines of inoculation become prominent, and an indurated longitudinal swelling, with all the characteristics of a pustule, soon projects above the neighbouring portions of skin. On the fifth day exudation commences, and from the sixth to the seventh day a large quantity of vaccine lymph may be collected. The line of inoculation appears slightly umbilicated and surrounded by a greyish-white zone and a hard peripheral swelling.
Vaccine may be collected from the fifth day in summer to the eighth day in winter.