598 Tuberculosis. 



for a long time (according to Lignieres, von Weber & Titze for two 

 years) thus making the slaughter of such animals for food a procedur(^ 

 of doubtful propriet3^ In addition to this objection, there is the possi- 

 bility that the bacilli, circulating freel}^ in the blood stream, may lodge 

 in the tissue of the udder and set up local tuberculous processes (Weber 

 & Titze). 



Control experiments conducted by Hutyra showed that intravenous injections 

 of 2 to 2.5 eg. of highly virulent bovine tubercle bacilli (doses which would invariably 

 kill control animals within two months) made in calves that had been immuniied 

 two months before, usually produced only a very few tuberculous foci confined almost 

 exclusively to the lungs and showing a tendency to encapsulation and healing. On 

 the other hand, injections of the same doses made subcutaneously resulte<l in lesions 

 confined to the area of injection. Administration of the same virus by the way of the 

 alimentary canal to animals previously immunized resulted in rather extensive affec- 

 tion of the tonsils. Similar results were obtained not only with Behring's original 

 bovo-vaccine but also with culture of human tubercle bacilli 4 to 6 weeks old. When 

 the resistance of the vaccinated animals was tested 7% and 17 months later the con- 

 trol infections resulted in extensive and partly in fatal general tuberculosis. 



Eber tested the resistance of four animals immunized by Behring's method 

 by repeatedly exposing them to animals with experimental tuberculosis. Two years 

 later, when they were slaughtered they were without exception found to be affected 

 with focal tuberculosis of a more extensive nature than that affecting the control 

 animals. 



In experiments conducted with 20 vaccinated animals by Eossignol & Yallee 

 in Mebin, with the same number of controls, wdiile giving gratifying results three 

 months later when 13 animals of each group were sul)jeeted to control infection, 

 lurther observation disclosed that two of the vaccinated animals became tuI:)ercuIous 

 and another died within 50 days from the effects of subsequent intravenous infection. 

 Furthermore, experiments carried out by Degive, Stubbe, Mullie & Lienaux in Belgium 

 and under Mazzini's direction in Italy, gave more cr less unsatisfactory results. 

 Finally, in an experiment made by Weber & Titze with 12 calves treated according 

 to Behring's instructions and which were exposed to infection from 2V2 to 9 monthr 

 later by subcutaneous or intravenous injections by inhalation and alimentary adminis- 

 tration of bovine virus, and in three instances exposed to natural infection, only one 

 animal, and that of the last group mentioned, remained free from tuberculosis. 



On experiences in practice, Eoemer (1005) reports on statistics covering 5,576 

 animals with the conclusion that vaccination resulted in a considerable decrease 

 in the prevalence of tuberculosis in the herds treated. Very evidently, however, this 

 favoralde showing must be ascribed to the improved hygienic conditions that were 

 established liecause other reports have been almost unanimously unfavorable. Thus 

 Hutyra failed to discover any improvement in the course of one to three years in 

 three herds that had been subjected to the Behring treatment. Eber, in 1907, in 

 testing 148 animals that had been treated strictly according to the prescribed 

 Behring m^ethod, found 56 reactors, i. e., 37.8%. Tuberculin tests conducted during 

 the two following years on seven estates gave 52.2% of positive reactions among 

 90 immunized cattle. The percentages increased with the age of the animals in 

 the same proportion as is usually observed in extensively infected herds (among 

 55 vaccinated animals 30.9% reacted at the first test, two years later, at the second 

 test, 58.2% reacted). Of 36 of the vaccinated cattle that died in the interval or 

 were slaughtered, 16 were tidDerculous. 



The results obtained on four estates in Galicia by Nowaek were similarly 

 unsatisfactory. Of 105 vaccinated cattle 44% reacted at the end of the first year 

 and of 138 vaccinated cattle 68% reacted at the end of the second year. Thirteen 

 of the reactors wei-e slaughtered and all found tuberculous. 



In Sweden Regner and Stenstroem conducted vaccination experiments since 

 1904 in 8 infected herds enforcing no other hygienic measures. Of 142 animals 

 vaccinated 61.2% reacted to a subsequent tuberculin test. After deducting 33 

 animals that were possibly infected at the time of vaccination 49.5% of the remaining 

 109 animals gave positive reactions, while 59% of the 61 control animals gave 

 positive reactions to the tuberculin test. On one estate 57% of 16 animals vaccinated 

 reacted to a subsequent test while only 20% of the 15 control animals reacted. In 

 a few cases, however, vaccination seemed to have a favorable influence and even 

 l)roduced curative effects in already tuberculous animals. 



Finally, Weber & Titze reji'ort on the ^accination of 206 cattle located on 

 6 different estates. The results are summarized l)y the statement that while some 

 of the animals became more resistant by the treatment the experiment was by no 

 means a conspicuous success. In one lierd that had previously been entirely freed 



