22 INFECTIOUS AND PARASITIC DISEASES. 



By pycemia is understood an infection in which the 

 micro-organisms have estabhshed suppurating foci 

 in different parts of the body. Where the several 

 locahzations have had their origin in another, single 

 focus, the former are often, although erroneously, spoken 

 of as metastatic abscesses. 



Heretofore the course of a disease due to 

 Combined only one infectious agent has been described , 

 Infections, and while we usually, in acute disease, 



are dealing with a single or uncombined 

 infection, the opposite, mixed or combined infections, 

 are not uncommon. Thus occur together measles 

 and scarlet fever, measles and whooping-cough, scarlet 

 fever and diphtheria, typhoid fever and pneumonia, 

 etc. When two infections occur in the same individual, 

 the symptoms of one disease are likely to be masked or 

 held in abeyance by those of the other, the extent to 

 which this takes place depending upon whether they 

 develop simultaneously or in succession. It also 

 depends upon the nature of the diseases. Thus pneu- 

 monia for a number of days may run so typical a course 

 in a person suffering from consumption as to deceive 

 the ablest clinician into believing that only one disease, 

 pneumonia, exists. On the other hand, pneumonia in 

 the alcoholic, in the sufferer from some chronic dis- 

 order, e.g., Bright's disease, diabetes, chronic heart 

 disease, or coming on during the course of an acute 

 infection, may be entirely overlooked in spite of the 



