INFECTIOUS DISEASES OF CATTLE. 44'? 



human beings are subject, though \"ery rarely, to the disease of the 

 lungs and the digestive organs. In the former case, the spores are 

 inhaled by workmen in establishments in which wool, hides, and rags 

 are worked over, and it is therefore known as wool-sorter's disease. 

 In the latter case the disease is contracted by eating the flesh of dis- 

 eased animals which has not been thoroughly cooked. These forms 

 of the disease are more fatal than those in which the disease starts 

 from the skin. 



BLACKLEG. 3 



Blackleg, blackquaiter, quarter-ill, symptomatic anthrax, charbon 

 symptomatique of the French, Rauschbrand of the Germans, is a 

 rapidly fatal infectious disease of young cattle, associated with external 

 swellings which emit a crackling sound when handled. This disease 

 was formerly regarded identical with anthrax, but investigations car- 

 ried out by various scientists in recent times have definitely proved 

 the entire dissimilarity of the two affections, both from a clinical and 

 causal standpoint. The disease is produced by a specific bacillus, 

 readily distinguishable from that causing anthrax. (PI. XXIX, fig. 4. ) 

 Cattle between 6 months and 2 years of age are the most susceptible. 

 Sucking calves under 6 months are rarely attacked, nor are they as 

 susceptible to inoculation as older animals. Cattle over 2 years of 

 age may become affected, but such cases are infrequent. Sheep and 

 goats may also contract the disease, but man, horses, hogs, dogs, 

 cats, and fowls appear to be immune. 



Like anthrax, blackleg is more or less restricted to definite localities. 

 There are certain pastures upon which the disease regularly appears 

 in the summer and fall of the year. As to any peculiarities of the 

 soil nothing is definitely known. Some authors are inclined to regard 

 moist, nndrained, and swampy pastures favorable to this disease, but 

 these theories will hardly hold, as it is found in all kinds of soils, in 

 all altitudes, at all seasons of the year, and under various climatic 

 conditions. It occurs in this country from the Atlantic to the Pacific 

 and from Mexico to Canada, but it is more prevalent in the Western 

 and Southwestern States. In Europe it exists in France, various 

 parts of Germany, in Belgium, Norway, Denmark, Italy, and on the 

 Alps of Switzerland. In Africa it occurs in Algeria and to some 

 extent in Natal and bordering countries. In South America it pre- 

 vails quite extensively throughout Argentina. Cattle in Cuba and 

 Australia also suffer. 



The cause of the disease is a bacillus resembling in some minor 

 respects the anthrax bacillus and differing but little from it in size, 

 It also possesses the power of forming within itself a spore. In 



«For detailed information regarding blackleg and the free distribution cf black- 

 leg vaccine, write 6c this Department for Bureau of Animal Industry eircrlars 

 Nos. 23 and 31. 



