Appearance of Infection in Flocks Previously Negative 



During the past year infection was detected in five flocks which had been 

 negative for two or more years. Table 3 gives a brief summary for each 

 flock. The amount of infection detected was very small in all flocks. The 

 source of infection could not be determined in three cases; whereas in 

 two, the feeding of garbage and custom hatching were incriminated. 



Table 3. Appearance of Infection in Flocks Previously Negative 



Flock 



Number 

 of Years 

 Negative 



Flock 

 Total 



1940_41 Season 



Number 

 Tested 



I'ositive 

 Tests 

 Percent 



Explanation for Infection 



510 

 486 



510 



486* 



1.18 

 0.00 



Feeding garbage 



1,300 



3,2 76 

 3,264 



1,280 



3,276 

 1,007' 



0.16 



0.37 

 0.00 



Unknown 

 I 'nknown 



3,114 

 2,663 



2,660 



3,114 



2,663* 



684* 



0.29 

 0.04 

 0.00 



Unknown 



1,066 



941 



Custom hatching 



'Represents retests. 



Flock 1 revealed six reacting birds among 510 tested. On retest no 

 more reactors were detected. 



Flocks 2 and 5 revealed two and one reactors respectively. Neither of 

 these flocks was retested. 



Flock 3 revealed 12 reactors among 3,276 birds tested and on partial 

 flock retest revealed no reactors. 



Flock 4 revealed 9 reactors among 3,114 birds tested. In a second test 

 of part of the flock, one additional reactor was detected. A third test of 

 the entire flock was negative. 



Since the majority of "breaks" occurred in flocks which had been neg- 

 ative for more than two years, one is led to believe that the infection had 

 been introduced recently from an outside source. It is difficult to con 

 ceive that the small amount of infection found could escape detection for 

 four or more years. While the number of "breaks" may be considered 

 small, poultrymen should appreciate the fact that many possible avenues 

 exist through which pullorum infection may enter a flock. Therefore to 

 avoid "breaks" one should observe the following preventive measures at 

 all times as far as is humanly possible: 



