254 



BUREAU OF ANIMAL INDUSTRY. 



Cause and prevention of swine teague, T. S:>nTH (pp. IGG, 

 plates 12). — This is the second special report on the iuvestigatious of 

 infectious swine diseases conducted by the Bureau, the first being on hog- 

 cholera (see Experiment Station Eecord, yol. i, p. 103). The present 

 volume contains the details of investigations which have led to the dif- 

 ferentiation of swine plague as a disease distinct from hog cholera. 

 After a short introduction the subject is treated under the following 

 heads: Brief description of the methods emidoyed in the investigations; 

 brief summary of the earlier investigations of swiiu^ league (18S0-8M) in 

 Illinois, Iowa, Maryland, and the District of Columbia; investigations 

 of 1889-90 in the District of Cohnubia and New Jersey; swine plague 

 ba<'teria, general characters, and resistance to dCvStructive agents; 

 pathogenic action of swiiie-phigue bacteria — (1) ellect on small animals, 

 (2) the disease in swine as produced by the inoculation of cidtures, (3) 

 swine plague as observed in cpizoiitics. (4) disease of the digestive 

 tract in swine plague; att<'nuated s\vine-]ilague bacteria in spora<lic 

 cases of pneumonia, in septic diseases of swine, and in the ui)per 

 air passages of healthy swine and other domesticated animals: other 

 investigations of swine plague in America and Europe; i)ractj(al 

 observations — (1) conditions which may favor or oppose outbreaks, (1*) 

 distribution and transmission of swine-plague bacteria, (3) relation of 

 hog cholera to swine plague, (4) relation of swine plague to diseases of 

 other domesticate<l amimals. (.">) measures to be taken in the prevention 

 of swine plague; conclusions; ai>pendix — the presence of septic bac- 

 teria probably identical with those of swine plague in the upper air 

 passages of domestic animals other than swine, by Y. A. ^Moore. 



The general conclusions from the investigations reported are thus 

 stated : 



(1) There arc tAvo iudepeiident infectious diseases of swine, swine plague and ho? 

 cholera, each caused by an easily recognizaltle, specific disease germ. 



(2) Swine ])lague (in those outbreaks which have come to our notice) is lin\ited 

 chielly to the lungs in its destructive etlect. The intestines may be and frequently 

 are involved in the disease process. Hence it is au infectious pneumo-enteritie rather 

 than an infectious pneumonia. 



(3) There is considerable variation in the virulence or disease-producing power of 

 swinc-plaguc bacteria from different outbreaks. The greater the virulence, other 

 things being equal, the severer and more extensive the epizootic. 



(4) The bacteria of Schwcincseuchc (German disease of swine) .ire identical with 

 those of swine plague. 



(5) In the upper air passages of a certain percentage of healthy swine, cattle, dogs, 

 and cats, bacteria exist which belong to the species of swine-plague bacteria, and 

 w hich as a rule possess a relatively feeble virulence. While it is probable that suih 

 bacteria may produce disease it may be regarded as pretty certain that it is largely 

 aided by secondary causes producing unthriftiness, and is merely sporadic and not 

 comnuinicable. 



(6) Inmany epizootics of swine disease both hog cholera and swine-plague bacterid, 

 as well as the respective lesions of these liacteria, coexist. Such mixed diseases arc 



