INFECTIOUS DISEASES 297 



dental inoculation in examining- the carcass of animals lliat 

 have died of the disease. 



Cause. — Anthrax is caused by a rod-shaped, spore-producing 

 microorganism, Bacillus anUimcis (i'ig. lOo). It gains 

 entrance to the body by way of the intestinal tract, lungs 

 and air-passages and the skin. The bites of insects play an 

 important part in the distribution of the disease in some lo- 

 calities, but the most common method of infection is by 

 way of the digestive tract, through eating and drinlcing food 

 and water contaminated with the anthrax germs. The spores 

 of the B. anthracis are very resistant to changes in temperature 

 and drying. They may live for years in rich, moist inundated 

 soils, lliver-bottom and swampy hinds that have become in- 

 fected with discharges from the bodies of animals sick with 

 anthrax, and by burying the car- ^ 



casses of animals that have died of ' ^' * *V 



this disease, retain the infection for • »> 



many years. Anthrax is very ^ ***» 

 widely distributed. It is most prev- *'^ 4^ .. 



alent in the southern portion of the jt 



United States, especially the lower y^ ^ . \> 



portion of the Mississippi Valley. *•'/ » 



The sympto7ns vary 171 dijferent \^ -.^n*' 



cases, depending on the organs af- --v^. . ^^^ 



fected, and the virulence and 



Fig. 103. — luicillu.^ anthracis. 



amount of virus introduced. The 



apoplectic form is very acute. The disease sets in suddenly ; the 

 animal trembles, staggers, falls and dies in a convulsion. Blood 

 may be discharged from the nose and with the urine and faeces. 



In the ahdominal form, abdominal pain, diarrhtca, prolapse 

 of the rectum, bloating and doughy swellings in the region of 

 the abdomen occur. 



In the thoracic form, the svanptoms are bloody discharge from 

 the nostrils, salivation, rapi<l, ditlicult ])reathing and swelling in 

 the region of the throat. Local or skin lesions may occur in con- 

 junction with, or independent of, the above forms of disease. 



