Serum-therapy has been advocated for years by De Schweinitz, and under the auspices of the Bureau of Animal Industry it has been given a wide trial, but it has not met with the full success that was at first claimed for it. The serum is prepared in a similar way to that of hog cholera and is similarly employed. It is open to the same class of objections, and though when skillfully employed it will reduce the mortality, it does not yet seem to have reached the point at which it can be recommended as a profitable investment. Like all temporizing measures it draws attention from the sounder and more economical measure of extinction and is indirectly a means of the perpetuation and even the diffusion of the infection. So long as extinction cannot be secured, this is a less valuable alternative for the adoption of owners of high priced hogs.
MODIFIED AND COMPLEX FEVERS OF SWINE.
Double infections. Varieties of bacillus choleræ suis, and bacillus suis pestis. McFadyean’s swine fever bacillus. Marseilles swine plague bacillus.
We accept fully the duality of the Hog Cholera and Swine Plague, though this duality has been hotly contested on both sides of the Atlantic. Many of the best observers in Europe now support this position. These include Selander, Bang and Jensen who are familiar with the svinpest (hog cholera) of Scandinavia; Kitt, Friedberger and Fröhner who are familiar with the Schweineseuche (swine plague) of Germany; Raccugla, Canova and others in Southern Europe; and Lignieres and others in France who have studied the hog cholera and pasturellose porcine (swine plague).
But the conceded duality of these two diseases as they occur in typical examples in swine, does not account for all the infectious fevers of swine, in which these microbes or others closely allied to them may figure. Salmon, Smith and their coadjutors describe double infections in the same system, in which both the bacillus choleræ suis and the bacillus pestis suis figure, and in which there result a combination of symptoms and lesions, that together represent both of these germs. It may be that one or other of these germs in a given outbreak, shows a predominance in potency so that the symptoms are more characteristic of it than of its companion; it may be that the more potent germ kills the victim, quickly by an acute septicæmia and gross lesions that would apply almost as well to one germ as to the other; or it may be that both act moderately and the attack is protracted with resulting lesions in both lungs and bowels that respectively suggest the plague and the cholera.
Then as regards varieties in the individual germ. Th. Smith recognizes this as a frequent condition and describes no less than seven different types of bacillus choleræ suis which he had studied and which varied in morphology, cultural qualities and virulence. Lignieres found that the virulence especially of bacillus suis pestis is very easily affected by successive passages through the bodies of small experimental animals. We ought not to be surprised then if we find in different epizoötics, in different countries and even in the same, bacilli which for the time at least show characteristics different from those to which we have been accustomed. These give us varying phases of septicæmia which however come together in one great class. Two of these types which have been placed on record may be here named. For others see septicæmia hæmorrhagica of cattle and sheep.
McFadyean’s Swine Fever Bacillus. The characters of this microbe found constantly by McFadyean in swine fever, approximates closely to the hog cholera germ in morphology and motility and in its deadly action when eaten, while it approaches toward the swine plague germ in its cultural habits on potato, gelatine and agar, and in alkaline culture liquids, and finally it differs from both in the absence of pathogenesis to Guinea pigs and in its very moderate action on rabbits. The symptoms and lesions of the swine fever of Great Britain are those of the hog cholera of America rather than of swine plague.
Marseilles Swine Plague Bacillus. This microbe was found by Rietsch and Jobert in a febrile epizoötic of swine at Marseilles, and was studied by Caneva and Bunzl-Federn separately. The latter identified it with the bacillus of ferret septicæmia, as described by Eberth and Schimmelbusch. It was longer and thicker than the hog cholera bacillus, twice as long as broad, actively motile, with flagella, and differed from bacillus choleræ suis, in its polar staining, its free growth in acid media, in acidifying and coagulating milk, and in its forming both indol and phenol in peptonized bouillon.
In this case the source of the disease was in importations from Africa (Fouquet), and it spread widely in Southern France for nine months. It proved almost constantly fatal, in from four days to two or three weeks. The symptoms were weakness especially in the hind limbs, with more or less fever, constipation often followed by diarrhœa, an infrequent cough, and red blotches on the skin. In chronic cases ulcers formed in the mouth and intestines especially the cæcum and colon. Appetite was often retained to the end. The young, under a year old, were the chief sufferers. It made 20,000 victims in several months in the province of Bouches-du-Rhone.