146 INFECTIONS CAUSED BY MOLDS 



able that most laboratory personnel where cultures of Coccidioides 

 immitis are handled sooner or later become infected. Fortunately 

 most of these infections are mild or inapparent, but unnecessary 

 risks should be avoided. 



If, in making a laboratory diagnosis by culture, there is doubt 

 about the identity of a fungus isolated, 1 ml. of a heavy suspension 

 of the spores can be injected intraperitoneally into a white mouse. 

 Lesions in which the characteristic parasitic growth phase of the 

 fungus can be demonstrated appear in animals killed after 5 or 6 

 days, and most inoculated mice die in 7 to 14 days. Intratesticular 

 inoculation of guinea pigs has been recommended as a diagnostic 

 procedure but the mouse is a cheaper as well as a more susceptible 

 test animal. 



Treatment. No specific treatment has been found uniformly suc- 

 cessful in coccidioidomycosis. According to Smith treatment should 

 consist of rest and supportive therapy directed toward assisting the 

 patient in the arrest of the infection. 



Morphology in Tissue. Coccidioides immitis exhibits in a striking 

 manner the dimorphism found in most pathogenic fungi. In animal 

 tissue the spores of the fungus are small spherical cells 1 to 4 microns ■ 

 in diameter. They are to be found frequently within phagocytes 

 (Fig. 73). These cells never bud but increase in size to upwards of 

 80 microns in diameter, the usual range of mature cells being 20 to 

 60 microns in diameter. The structure during this period of develop- 

 ment varies to some extent with the tissue invaded and the strain of 

 fungus. The stainable protoplasm may fill the cell or, especially in 

 experimental infections in mice and guinea pigs, be confined to a 

 comparatively narrow peripheral layer. In the latter case the large 

 central vacuole is eventually filled with an indefinite number of endo- 

 spores (sporangiospores). The process of spore formation was first 

 clearly described in detail by Wolbach and by Ophuls. Their obser- 

 vations have been confirmed by many later students. The proto- 

 plasm becomes cut up by radial and periclinal cleavage planes, the 

 process originating at the periphery and progressing toward the 

 center. The first cleavage planes cut out large multinucleate masses 

 which are usually subdivided by other cleavage planes to form very 

 numerous small spores. However, in some cases the process may be 

 interrupted at an intermediate point and only a few large spores may 

 form. After spore formation is completed the w^all of the parent cell 

 ruptures and the spores pass into the adjacent host tissue where they 

 repeat the cycle. No other cell form is known in the parasitic growth 

 phase. The endospores are infective, as can be demonstrated experi- 



