754 Ringworm 



Pathogenesis. The trichophytons are pathogenic for man and 

 for the lower animals. They spread from animal to animal by con- 

 tact and by inoculation. Men, dogs, cats, horses, sheep, goats, and 

 swine all suffer from the infection. The growth of the hypha be- 

 tween the epidermal layers causes a chronic inflammation, with 

 hyperemia, desquamation, the formation of some papules, and oc- 



^^ ^r .^^ 



Fig. 316. Trichophyton tonsurans. Primary cultures twenty days old on 

 maltose agar-agar. Natural size (Sabouraud). 



casional pustules. The invasion of the hair-follicles and the growth 

 of the fungi into the hairs cause them to become fragile and break 

 off, as well as to loosen and drop out. 



The name "barber's itch" results from the frequent transmission 

 of the infection by the barber's razors. The disease is easily trans- 

 missible and precautions should always be taken to prevent its 

 dissemination. 



