CHAPTER VI 

 MICROBIAL DISEASES OF MAN AND DOMESTIC ANIMALS 



DISEASES CAUSED BY MOLDS* AND YEASTS 



The diseases produced by fungi in higher animals are mostly 

 localized infections of the skin (dermatomycoses), of the mouth and 

 throat (thrush), of the lungs and air passages (pneumomycoses), and 

 of the lymphatics (Sporotrichosis and Saccharomycosis). 



PNEUMOMYCOSIS f 



ASPERGILLOSIS. The fungus disease of the lungs and air cells of 

 birds is quite uniformly attributed to Aspergillus fumigatus which is 

 widely distributed in the soil and upon feed and grains. The agency of 

 this species in causing disease is well established. It grows best at 

 blood-heat. Inoculation experiments have produced the disease in 

 animals. Isolated cases are recorded in which this organism is regarded 

 as the cause of disease in horses or cattle and even man. Biologic 

 forms of A. fumigatus are very widely distributed. Many of them are 

 readily separated by cultural characters. Pathogenicity is not lim- 

 ited to one or a few strains since lesions have been described as due to a 

 wide range of the varieties of this group. Other species of Aspergillus, 

 A. flavus, A. nidulans, A. niger, have been listed among pathogenic 

 forms from their presence at times in diseased tissue. Whether these 

 species are ever a primary cause of disease is doubtful, but their pres- 

 ence and activity in such infected areas has been established. 



Secondary Infections. Spores of any species of fungus found in 

 the locality may find lodgment in wounds, orifices open to the outside, 

 such as the external ear or the air passages. Many of these spores will 

 germinate in such situations. If favored by dirt, pus, mucus, or exist- 

 ing pathological condition the resulting growth in some species de- 

 velops into a secondary infection; most species lack entirely the power 

 to produce disease. The appearance of molds, especially species of 



* Arranged ^enerically as far as possible, 

 t Prepared by Charles Thorn. 



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