Special report on the cause and prevention of swine plague : results of experiments conducted under the direction of Dr. D. E. Salmon ... / by Theobald Smith.

  • United States. Bureau of Animal Industry.
Date:
1891
Catalogue details

Licence: Public Domain Mark

Credit: Special report on the cause and prevention of swine plague : results of experiments conducted under the direction of Dr. D. E. Salmon ... / by Theobald Smith. Source: Wellcome Collection.

    32/198 (page 28)
    VI. During November, 188S, the writer was directed to make some in- vestigations in Iowa,* where swine diseases at that time were prevail- ing to a considerable extent. In the vicinity of Mason City pigs from three herds, some distance apart, were examined. The lesions observed were both intestinal and pulmonary. The intestinal lesions, though varying considerably in appearance and intensity, did not differ, on the whole, from those observed in hog cholera. The lung lesions varied considerably in character and extent, from a slight collapse in a single lobe to almost total hepatization, accompanied by exudative pleuritis. The investigations were limited to post mortem examination and cultures from the spleen. From each spleen small bits of tissue were removed to two tubes of agar. In addition, portions of diseased lung tissue and ulcerated mucous membrane from the large intestine were cut out and transferred to sterile test tubes plugged with cotton wool for inoculation into rabbits. Ten pigs were examined in this manner. In but one case did the spleen pulp show any bacteria under the microscope, and in this case they were streptococci. In but one agar x- tube of the spleen series did anything develop. This was a motile bacillus, resembling the hog-cholera bacillus in form, but differing in its growth on agar, in bouillon, and in gelatine, this growth being in all cases more vigorous. Of two mice and one rabbit inoculated, one mouse died in 5 days. The lesions were indefinite and did not point to hog cholera. Moreover, the other mouse and the rabbit remained unaffected. With particles of diseased lung tissue and mucous membrane from some of these cases a considerable number of rabbits and some mice were inoculated. Of those that died some contained no bacteria of any description. Those inoculated from three cases out of ten died of swine plague since these bacteria were found. A few survived the inoculation. The nature of this disease was not, therefore, cleared up by these in- vestigations, since the results were not uniform. While in hog chol- era the bacilli are present in the spleen, and readily obtained therefrom by cultivation, they were not present in the spleens of these ten cases. As already stated, swine-plague bacteria were obtained from three cases. They were quite virulent, as the inoculations upon pigs show. Thus one pig, which received 9 cubic centimetres of a bouillon culture into the right lung through the chest wall, died within 20 hours of septi- cmmia, the injected bacteria being present in the spleen in considerable numbers. Another pig, which received a subcutaneous injection at the same time, remained well. Somewhat later two pigs received into the right lung 1J cubic centimetres and 3 cubic centimetres of a bouillon * Report of the Bureau of Animal Industry for ISST-'QS, pp. 135-145, whore a de- tailed account of this work is given.