Appearance of Infection in Flocks Previously Negative 



During the past year infection was detected in six flocks which were negative 

 the previous season. While the number of "breaks" may seem small in com- 

 parison with the total number of flocks tested, the significance of this re-infection 

 should not be minimized. These cases point out the necessity of annual testing. 

 The data in Table 4 show that in all but one flock the percentage of reactors was 

 less than one. In this one flock the infection was attributed to the practice of 

 custom hatching for miscellaneous flocks and to the purchase of questionable 

 stock. Flock 6 derived its infection from a contest bird. In this case the owner 

 fortunately maintained the contest birds in isolation and quarantine until their 

 status was determined. The origin of infection in Flock 3 was not definitely 

 determined, in view of the fact that complete information concerning management 

 practices was not received. The source of infection in Flocks 1, 2 and 4 is classified 

 as unknown, since the owners could not recall any possible mismanagement that 

 might permit infection to enter. 



The fact that in five cases the amount of infection was very small suggests 

 that the disease was introduced onto the premises after the chicks were removed 

 from the incubator. It further points out that little or no dissemination of the 

 disease occurred after its introduction into the flock. 



♦Represents retests. 



These findings should impress strongly upon the minds of poultry breeders 

 that one cannot be too careful in observing the following control, eradication, 

 and prevention measures. 



1. All birds on the premises should be tested annually. 



2. If infection is present, the entire flock should be retested within four to 

 six weeks until a negative report is obtained, provided the value of the birds 

 justifies the expenditure for testing. 



3. Every reactor, regardless of its value, should be removed from the premises 

 and sold for slaughter immediately upon receipt of the report. 



(6) 



