BORREL, A. Microbes des eaux et culture d'un protozoaire minimal. Ibid., p. 61. BORREL, A. Etudes sur la clavelée; sérothérapie et séroclavelisation. Pasteur, Paris, tome 17, no. 11, p. 732. 25 Nov., 1903. CELLI, A., & BLASI, D. DE. Ann. de l'inst. Ist das Wuthgift filtrirbar? Deut. med. Woch., Berl., 29. Jahrgang, No. 50, p. 945-946. 10. Dez., 1903. CENTANNI, Eug. Die Vogelpest; Beitrag zu dem durch Kerzen filtrirbaren Virus. Cent. f. Bakt., 1. Abt., Originale, 31. Bd., No. 4, p. 145-152; No. 5, p. 182-201. 14. Feb. and 27. Feb., 1902. DUBOIS, ALBERT, Une maladie infectieuse des poules à microbes invisibles. Comp. rend., Soc. de biol., Paris, tome 54, no. 29, p. 1162-1163. VON ESMARCH, ERWIN. 31. Oct., 1902. Cent. f. Bakt., Ueber kleinste Bakterien und das Durchwachsen von Filtern. LODE, A., & GRUBER, J. Bakteriologische Studien über die Aetiologie einer epidemischen Erkrankung der Hühner in Tirol (1901). Cent. f. Bakt., Jena, 1. Abt., 30. Bd., No. 16, p. 593-604. 7. Nov., 1901. 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Cinquantenaire de la société de biologie; volume jubilaire. Paris, 1849-1899, p. 440–449. SANARELLI, G. Das myxomatogene Virus; Beitrag zum Studium der Krankheitserreger ausserhalb des Sichtbaren. Cent. f. Bakt., 1. Abt., 23. Bd., No. 20, p. 865-873. 1. Juni, 1898. SCHÜDER. Der Negri'sche Erreger der Tollwuth. Deut. med. Woch., 29. Jahrgang, No. 39, p. 700. 24 Sept., 1903. SIEDENTOPF, H. & ZSIGMONDY, R. Über sichtbarmachung und Grössenbestimmung ultramikroskopischer Teilchen, mit besonderer Anwendung auf Goldrubingläser. Annalen der Physik., Leipzig, 10 Bd., No. 1, p. 1-39. 1903. WHERRY, WM. B. Experiments on the permeability of the Berkefeld filter and the Pasteur Chamberland bougie to bacteria of small size. Journ. of med. research, v. 8, no. 2, p. 322-328. Nov., 1902. NEW FACTS CONCERNING THE ETIOLOGY OF HOG CHOLERA." By E. A. DE SCHWEINITZ, M. D., PH. D., AND M. DORSET, M. D., Chief and Assistant Chief of the Biochemic Division, Bureau of Animal Industry. PRELIMINARY REMARKS. During the course of the investigations concerning hog cholera which have been carried on by the Biochemic Division of the Bureau of Animal Industry, certain outbreaks of that disease were met with which apparently were not produced by the hog-cholera or the swineplague bacilli. The disease was highly contagious and fatal to a large proportion of the hogs which were attacked. These observations, which were inexplicable previous to the researches herein recorded, together with the great variations in the physical symptoms and the postmortem lesions encountered in different outbreaks of so-called "hog cholera,” have led us to institute experiments to determine, if possible, whether or not there are other infectious diseases among hogs in this country than those caused by the hog-cholera and swine-plague bacilli, and also to ascertain what was the etiological agent in those outbreaks of disease mentioned above, which apparently did not depend upon these bacilli for their existence. These experiments have not yet been completed, but have gone far enough to enable us to publish, this preliminary information. The outbreaks of disease which have furnished material for the study of the questions just outlined have all had their origin in southwestern Iowa, but, owing to the great distance of that point from Washington and the fact that it was not possible to establish a satisfactory laboratory in the field, it has been found necessary to expose a certain number of animals to infection in Iowa and then transport them by express to the Bureau Experiment Station near this city, where all the inoculations were made by the superintendent of the station. After once bringing the disease to Washington no trouble was, as a rule, experienced in perpetuating it by transferring from one animal to another. The experiments have reached such a stage that we feel justified in stating that there is an infectious disease among hogs in this country which can not be distinguished clinically from hog cholera, and which may be reproduced by infecting with material which contains no hoga The article in the main is published as Circulars Nos. 41 and 43 of this Bureau. cholera bacilli. It will be understood that at this time no estimate can be made as to the frequency with which this disease occurs, nor as to its distribution throughout the country. Below is presented a brief outline of the facts which have been established in regard to this disease. ETIOLOGY. Nothing can be stated at present as to the cause of this disease. It has been demonstrated, however, that the primary cause is neither the hog-cholera bacillus nor the swine-plague bacillus. We have transferred the disease repeatedly from one hog to another by subcutaneous inoculation of certain body fluids, these fluids being always proved, by careful bacteriological examinations, by filtration through the finest porcelain filters, and by the inoculation of guinea pigs and rabbits, to be free from hog-cholera and swine-plague bacilli. We have used a system of checks upon the various inoculation experiments by means of which we have been able to exclude all chance of accidental pen infection or of infection through the syringes. The disease is highly contagious, healthy pigs that were allowed to come in contact with sick animals almost invariably becoming sick within the usual period of incubation. So far we have been unable to communicate this disease to any other animal than hogs. Rabbits and guinea pigs are entirely insusceptible to inoculations that are of sufficient size to destroy pigs weighing from 30 to 40 pounds. SYMPTOMS. The period of incubation after exposure to sick animals, or after a subcutaneous inoculation of infectious material from sick animals, varies from five to twelve days, the usual time elapsing between exposure and visible signs of illness being seven days. The first symptoms noticed are that the pig is slightly indisposed; there is loss of appetite and listlessness, but, as a rule, nothing else on the first day. By the second day of visible illness the animal is usually very sick, hollow in flanks, and has a staggering gait. There may or may not be diarrhea, and the feces are frequently blood-stained. Almost without exception the eyes are sore and the lids glued together. The symptoms just enumerated become gradually more pronounced until the death of the animal, which takes place, as a rule, within seven days after the appearance of the initial symptoms and approximately two weeks after the first exposure to infection. It must be explained that the experimental pigs which we have used weighed from 15 to 40 pounds, and it is possible that in the case of older and larger animals the period of incubation and the course of the disease may be of longer duration. This point, together with many others, is left for future determination. POSTMORTEM APPEARANCES. The skin over the abdomen may be reddened throughout, or these cutaneous lesions may appear as more discrete purpuric areas of varying size. Upon removing the skin of the thorax and abdomen the subcutaneous areolar tissue is generally found to be thickly dotted with small ecchymoses. There is usually not the slightest evidence of inflammation at the point of inoculation if the animal has been injected subcutaneously. LYMPHATIC SYSTEM. The inguinal glands on both sides are reddened, as are the lumbar, retroperitoneal, mesocolic, mesenteric, and bronchial glands. The reddening of these glands varies in intensity; at times the hemorrhagic condition is slight, while at others it is so intense that practically all of the glands are deep red, approaching black in color. DIGESTIVE SYSTEM. (a) Stomach. There may be considerable congestion and inflammation of the mucosa and also small hemorrhages on the serous surface. (b) The small intestines usually present a large number of small ecchymoses on their serous surfaces and not infrequently the mucous surface is in the same condition. (c) Cecum and colon. This portion of the intestines, almost without exception, shows hemorrhagic areas on its serous and mucous surfaces, these hemorrhages being, as a rule, fewer in number and larger in extent than those seen in the small intestines. In the cecum and ascending colon it is not unusual to find large numbers of small newly formed ulcers which occasionally show a hemorrhagic center. (d) In several instances there has been a most. severe hemorrhagic inflammation of the rectum extending throughout its entire length. The intestinal contents are not infrequently bloodstained. (e) Liver. This organ is usually mottled, and may exhibit diffuse grayish areas which appear to be due to an increase of connective tissue. Small ecchymoses and areas of necrosis are not infrequently seen on the surface of the organ. The histological examination of this organ has not been completed. LUNGS. The lungs frequently show hemorrhagic areas on their surface, but, as compared with the other organs, are usually slightly affected. ᎻᎬᎪᎡᎢ. Hemorrhagic areas are occasionally seen on the surface of the auricles and ventricles. SPLEEN. The spleen is always enlarged, dark in color, and not infrequently shows small petechia on its under surface. H. Doc. 743, 58-2-11 |