266 



OPSONIC INDEX IN ACUTE INFECTIONS 



should expect to be caused thereby is not the cause of the crisis 

 and the patient's recovery. The short duration of the high level 

 of the index is interesting, as we know that the immunity left 

 after an attack of pneumonia is but temporary. 



A gradual rise of the index often takes place in staphylococcic 

 diseases e.g., boils ; and when the index is traced from day to day, 

 it may be seen that it is low to begin with, during the onset and 

 increase of lesion, but that it rises more or less gradually until it 



1 2 



Days of disease 



4 667 8 9 10 II 12 13 14 15 



II 



1-0 



FIG. 60. TYPES OF REACTION OF THE OPSONIC INDEX IN PNEUMOCOCCIC 

 INFECTION. (After Eyre.) 



(rt) Immediate, as seen in mild diseases ; (b) delayed ; and (c) progressive 

 decline, as seen in severe and fatal infections. 



reaches a point well above normal. At the same time the disease 

 begins to improve, suggesting again that the phagocytosis de- 

 pendent on the amount of opsonin in the blood is the actual 

 cause of the recovery. Very many observations of this type have 

 now been made with many organisms, and as a general rule we 

 may say that in acute diseases (excluding tubercle) the index is, as 

 a rule, low during the onset and culmination of the disease, and 

 raised during involution and recovery. Exceptions may be met 

 with, but the sequence of events happens too often to be a mere 

 coincidence (see Figs. 60, 61, 63, and 64). 



