046 



STATE BOARD OF AGRICULTURE. 



TABLE III.— SHOWING TIIK .\NTIBODY CONTENT OF HUMAN SERA, AT START, AT 

 HIGHEST POINT. AND AT 4 WEEKS AFTER LAST DRINKING. 



That Bad. abortus antibodies may appear in human sera, while an 

 individual is drinliing a Bad. abortus infected millc which is rich in anti- 

 bodies, is Shown in the above table. Of the seven persons drinking this 

 milk there was an increased antibody content in the sera of five (or over 

 seventy per cent). 



If the Bad. abortus antibodies present in the blood were due to an 

 infection of the individual by organisms being present in the milk, it 

 seems that we could expect a fairly high and lasting antibody content. 

 On the other hand, if the antibodies present are due to a passive im- 

 munity, we could expect but a weak reaction, which would persist for 

 but a short time after one had ceased drinking the milk. It seems to 

 the writer that the data given in the table suggest that the antibodies 

 present are due to a passive immunity. We have the individuals drink- 

 ing an enormous amount of antibodies daily and in over seventy per cent 

 of the cases an increase in the antibody content of the blood during 

 the eight weeks. In every instance the reaction is weak and shows a 

 tendency to die out when the infected milk is no longer being fed. The 

 fact that individuals were apparently in perfect health at all times dur- 

 ing this experiment is a further indication that there was no active 

 infection. 



That the Bad. abortus antibodies sometimes found present in human 

 blood are due to a passive immunity and are not due to an active in- 

 fection is further indicated by an experiment shown in Table IV. 



