352 ANTHRAX 



Experimental Inoculation. Of the animals commonly used 

 in laboratory work, mice and guinea-pigs are the most susceptible 

 to anthrax, and are generally used for test inoculations. If a 

 small quantity of anthrax bacilli be injected into the sub- 

 cutaneous tissue of a guinea-pig, a fatal result follows, usually 

 within two days. Post-mortem, around the site of inoculation the 

 tissues, owing to intense inflammatory oedema, are swollen and 

 gelatinous in appearance, small haemorrhages are often present, 

 and on microscopic examination numerous bacilli are seen. 

 The internal organs show congestion and cloudy swelling, with 

 sometimes small haemorrhages, and their capillaries contain 

 enormous numbers of bacilli, as has already been described in 

 the case of the ox (Fig. 108) ; the spleen also shows a corre- 

 sponding condition. Highly susceptible animals may be infected 

 by being made to inhale the bacilli or their spores, and also by 

 being fed with spores, a general infection rapidly occurring by 

 both methods. 



Anthrax in the Human Subject. As we have noted, man 

 occupies a middle position in the scale of susceptibility to 

 anthrax. It is always communicated to him from animals, and 

 usually is seen among those whose trade leads them to handle 

 the carcases or skins of animals which have died of the disease. 

 It occurs in two principal forms, the main difference between 

 which is due to the site of entrance of the organism into the 

 body. In one, the path of entrance is through cuts or abrasions 

 in the skin, or through the hair follicles. A local condition 

 called a " malignant pustule " develops, which may lead to a 

 general infection. This variety occurs chiefly among butchers 

 and those who work among hides (foreign ones especially). In 

 Britain the workers of the latter class chiefly liable are the hide- 

 porters and hide-workers in South-Eastern London. In the 

 other variety of the disease the site of infection is the trachea 

 and bronchi, and here a fatal result almost always follows. The 

 cause is the inhalation of dust or threads from wool, hair, or 

 bristles, which have been taken from animals dead of the disease, 

 and which have been contaminated with blood or secretions con- 

 taining the bacilli, these having afterwards formed spores. 

 This variety is often referred to as " woolsorter's disease," from 

 its occurring in the centres of the woolstapling trade (in 

 England, chiefly in Yorkshire), but it also is found in places 

 where there are hair and brush factories. 



(1) Malignant Pustule. This usually occurs on the exposed 

 surfaces the face, hands, forearms, and back, the last being a 

 common site among hide-porters. One to three days after 



