INFECTIOUS DISEASES 



LECTURE XXXII 

 ACTINOMYCOSIS— OR LUMPY JAW 



This disease is commonly called lumpy jaw or big head. It 

 is characterized by the development of peculiar enlargements 

 containing pus pockets, usually around the head. The disease 

 may also affect other external parts and internal organs. 



Cause. — The tumors and abscesses which characterize lumpy 

 jaw have a common origin ; namely the presence and activity 

 of a form of higher bacteria known as actinomyces {Actinomyces 

 hovis) aided by various common pus producing bacteria. When 

 the abscesses are opened, there is usually found in the interior, 

 thick glairy pus containing minute grains, usually yellow and 

 sometimes very abundant. These small grains may be bedded 

 in the diseased soft tissues of the tumors. Seen under a micro- 

 scope, these grains appear to be composed of radiating fila- 

 ments with club-shaped extremities around the border of the 

 mass. In artificial media it forms long, slender threads, often 

 branching. As the fungus multiplies and spreads the tumor 

 growths increase in size. The tumors are usually very firm on 

 account of the large amount of connective tissue which they 

 contain. The interior is somewhat honeycombed, and the pockets 

 are filled with characteristic pus containing the granules of 

 actinomyces. Animals affected are chiefly cattle, horses, and 

 sheep. 



Relation to public health. — Human beings are evidently sus- 

 ceptible to inoculation from this disease, but as the affected parts 

 of diseased carcasses are not commonly used as articles of human 

 food, and animal meats as a rule are cooked before being eaten, 

 there is ordinarily slight danger for human beings. The gov- 

 ernment meat inspection regulations pass carcasses which are 

 but slightly and locally diseased, and condemn those which are 

 extensively and generally diseased. 



Parts involved. — The external parts commonly affected are 

 the bones of the upper and lower jaws, soft tissues between the 

 two branches of the lower jaw, and tongue. This disease some- 



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