Makiiif? the tuberculin test. 



infected and exposed animals to the herds of 

 origin. This involves — 



(1) Tracing to herds of origin animals 



found with lesions of tuberculosis on 

 regular kill at slaughtering plants. 



(2) Tracing the origin of reactor animals 



found in tuberculin tests. 



(3) Tracing and follow up on exposed ani- 



mals associated with infected herds. 

 Success of the tracing system depends upon 

 close cooperation of many individuals — the vet- 

 erinary meat inspector, the stockyards veteri- 

 narian and stockyards officials, the livestock 

 hauler, the livestock market operator, State 

 and Federal livestock sanitary officials and 

 their respective field veterinarians, the veteri- 

 nary practitioner, the livestock dealer, and the 

 livestock grower. Greater efficiency in tracing 

 operations are borne out in figures for the 5 

 years 1955-59, during which 72,005 tubercu- 

 losis reactors were slaughtered. Of these, 5,539 

 or a total of 7.6 percent were found as a result 

 of tracing to herds of origin animals with le- 

 sions reported on regular kill. These reactors 

 were found by testing 164,824 cattle, or only 

 0.38 percent of the 43,922,211 cattle tested dur- 



ing the 5-year period. It is anticipated that an 

 even greater percentage of cases will be traced 

 as better identification and more complete rec- 

 oi'd systems are developed. 



Emphasis on epidemiology (field study 

 projects) 



Epidemiology in tuberculosis has received 

 increased attention. In cattle this involves 

 other species of animals, as well as man, as 

 potential sources of infection. 



As the incidence of tuberculosis in cattle has 

 been reduced, the close study of the interspecies 

 relationship of the various types of tubercu- 

 losis has become increasingly important. Avian 

 and human tuberculosis, for example, must be 

 considered in disclosure of possible sources of 

 infection to cattle. 



Special field investigations being conducted 

 in cooperation with State officials may aid in 

 developing still more effective procedures. 



Additional work in laboratory diagnostics 



As increased study and attention is given to 

 the epidemiological aspects of tuberculosis, 

 laboratory and diagnostic work has increased. 

 Specimens from reactor animals in problem 

 herds are processed through the laboratory, 

 where tissues are examined pathologically 

 and bacteriologically. This type of work in 

 diagnosis of tuberculosis is among the mo.st 

 involved and time-consuming of medical diag- 

 nostic procedures. However, as comprehensive 

 investigational studies are made, the laboratory 

 l)ecomes increasingly important in determining 

 the type of tuberculosis involved. 



Training in post-mortem examinations 



The Meat Inspection Division has developed 

 a guide that provides specific instructions and 

 information on post-mortem examination of 

 tuberculosis reactors. 



This guide makes possible the uniform ex- 

 amination of all tuberculosis reactors, whether 

 their slaughter is supervised l^y municipal. 

 State, or Federal inspectors. Special training, 

 under the direction of the Meat Inspection Di- 

 vision, has been given to ADE veterinarians 

 to achieve uniformity in the post-mortem ex- 

 amination of tuberculosis reactors. 



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