Immunization. 403 



As a matter of fact the procedure was mostly disapproved 

 of in the past, and played only a subordinate part in the 

 attempts to eradicate the disease. This may be explained prin- 

 cipally by the fact that in immunizing large herds those animals 

 are of course also inoculated which, although apparently healthy 

 nevertheless are already infected. In these animals the already 

 existing inflammatory process continues to develop in the usual 

 manner in spite of the inoculation and thus these animals, 

 which are believed to be no longer susceptible, continue to 

 spread the disease among those which have not been immunized. 

 A further disadvantage exists also in the frequent loss of the 

 tail as well as in the occasional fatal results of the method. 



Imnmnii-ation was introduced in the Spoelinger District of Holland in 1874, 

 as this territory had been so badly infected that the slaughter of animals could 

 not be carried out, and as a result of this procedure up to 1884 the annual loss 

 Avas re<luced from 1,208 to 135 cattle. According- to Degive 2.7% out of 6,706 immu- 

 nized animals acquired the disease between 18.50 and 1883 in the various countries, 

 while out of 2,453 animals, which were not immunized, 26.9% became later affected 

 with pleuro-pneumonia. In the German Empire, according to official reports, out 

 of 3,868 immunized animals 151 (3.9%) became affected in the period of 1891-1900 

 in previously immunized herds, while out of 546 not immunized animals 73 (13.4%) 

 became ill. In herds which were immunized only after the outbreak of the disease, 

 out of 3,287 immunized animals 394 (11.9%,) became subsequently affected with 

 pleuro-pneumonia. 



Results of the Immunization. After the inoculation of fresh, pure 

 lymph, a hard, painful and warm swelling in size like a nut to an 

 egg develops in about 907o of the animals, at the point of inoculation; 

 the animals keep the tail quiet and slightly bent upward, and at the 

 same time showing marked febrile symptoms. In favorable cases the 

 swelling disappears together with the febrile symptoms inside of 1 to 

 2 weeks; not infrequently however the swelling increases in size and 

 suppuration or even necrosis of the tip of the tail sets in. Occasionally 

 the inflammation may extend even to the root of the tail and to the 

 part around the anus, as well as to the connective tissue of the pelvis, 

 whereupon the animal dies from peritonitis which may be associated 

 with it, or from pyemia or septicemia. The cause of these dangerous 

 complications may almost invariably be attributed to the fact that the 

 vaccine originally contained foreign pathogenic bacteria,^ or that srich 

 organisms entered it during its preparation and preservation, or during 

 the inoculation. The number of deaths and losses of tails varies accord- 

 ingly from case to case. On an average 1 to 3% of the immunized 

 animals die, and 5 to 15% lose their tails. 



According to Haubner the deaths amount on an average to 1-2% (at the 

 highest 10%), the losses of tails to 5-10%. In Holland, in the Spoelinger District, 

 out of 147,971 immunized animals 1,285 (0.94%) died in the years 1878-1887, while 

 in Hasselt, the home of Willenis, the mortality among 184,275 immunized animals 

 did not exceed 1%. In Germany out of 17,520 immunized animals 141 (0.8%) 

 died as a result of the inoculation between 1891-1901. In some cases, however, the 

 losses were considerably greater. Thus Hildebrandt observed among 365 inoculated 

 animals 69 (18.9%) deaths, while on another occasion 49% of the animals remaining 

 alive lost their tails. Similar unfavorable results are reported by Omler. 



Technique of Inoculation. In the oldest method recommended by Willems, the 

 material which is used for the immunization consists of fluids from the lungs of an 

 animal affected with the acute form of pleuro-pneumonia, which had been slaughtered 

 immediately before the immunization. The hepatized part of the lung is incised 

 by a knife sterilized in a flame, whereupon the lymph accumulates in the depth of 



