904 Herpes Tonsurans. 



Indirect contagion also plays an important part and may 

 be occasioned especiallj^ by cleaning ntensils, blankets, harness 

 or objects on which the animals rub themselves. Moreover 

 persons may carry the fungus in their clothes or the disease 

 may develop from placing healthy animals in a stable which 

 has previously been occupied by animals that have been suffer- 

 ing from the disease (Schindelka). 



Sabouraud and Bodin are inclined to believe that the tricophyton funjfiis 

 thrives free in Nature on different plants and that animals are liable to contagion 

 on coming in contact with them. 



As predisposing causes the following may be noted : housing 

 in warm, damp, dirty stables and particularly basement stables 

 where the animals lie on a thick layer of manure ; in such stables 

 the disease frequently remains stationary. Maceration of the 

 skin by getting wet or from frequent washing assists the locali- 

 zation of the fungus, also excoriation of the skin, while exposure 

 to sun and wind, cold sta])les and living in the open are said to 

 inhibit the growth of the fungiis. Consequently herpes spreads 

 much in pasturing districts in fall, in damp summers and es- 

 pecially in winter (Pusch). 



The important role played by predisposing factors is shoven by the fact that one 

 cannot always succeed in transmitting the disease artificially in its progressive 

 form to other animals of the same species, because one is not always in a position 

 to produce the favorable conditions. Thus for instance in one experiment of the 

 authors infection failed to occur in a calf although it was kept for three weeks in 

 constant and immediate contact with a badly affected calf and although macerated 

 scab material had been rubbed on the scarified or shave<l skin. On the other hand a 

 sheep suffering from moist eczema on the back and brought in contact with the same 

 subject acquired a general attack of herpes. A dog affected with acariasis was also 

 infected, while another healthy dog escaped. 



Susceptibility. The cow and the horse are most susceptible 

 to natural infection, then follow the dog and the cat, while the 

 other domestic animals are infected only very exceptionally. 



The susceptibility is in so far influenced by the condition 

 of the skin as animals with tine, sensitive hides are easily at- 

 tacked. According to the investigations of Pusch young ani- 

 mals are for this reason more inclined to the disease than old 

 ones, whose skin is much more resistant, and fine skinned breeds 

 in general are especially susceptible to the disease. The in- 

 fluence of the color of hair on the incidence of the disease may 

 be assumed from the fact that animals with dark hair are more 

 frequently and severely attacked than animals with light colored 

 or white hair. 



The affected portions of the skin are not protected after 

 recovery from fresh attacks of the complaint, as the experiments 

 of Gerlach and the clinical observations of R. Frohner prove 

 (Pusch believes that an immunity after recovery from an at- 

 tack is not impossible). 



There are numerous records of contagion to man through affected animals, 

 especially through cattle, horses and dogs. Principally persons who are occupied 

 with the care, attendance, treatment or milking of sick animals have been infected. 



