Departmental Activities. 307 



Bedford working at Onderstepoort (see Third and Fourth Reports of 

 the Director of Veterinary Research). 



These results have often been questioned by farmers who believe 

 that an infected kraal is capable of retaining the infection for months 

 or even for a year and longer. It was with the object of demon- 

 strating the erroneousness of this belief that the investigations were 

 again undertaken by Mr. Curson. The suggestion of having the 

 results obtained by Shilston and Bedford retested was first made by 

 the Somerset East Agricultural Society. The Division of Sheep then 

 took the matter in hand, and it was decided that Mr. Curson would 

 arrange and supervise the experiment in Somerset East, the sheep 

 inspector of the area actually controlling the experimental animals. 

 In addition to this, three similar experiments were concluded in 

 Grahamstown. It may be added that further similar experiments on 

 a much larger scale are being carried out at Onderstepoort. A full 

 detailed report of all this work will be published later. These notes 

 are merely intended to give farmers the outstanding results of Mr. 

 Curson's tests. 



In the first experiment an open sheep kraal measuring 80 x 43 feet 

 was used. A flock of sheep, 12 of which were infected with scab, was 

 kept in it for over a month. The kraal was then left empty for 

 sixteen days, after which period six clean sheep were brought into 

 it and left there for 27 days. All these sheep remained free of scab. 



In the second experiment an open sheep kraal 21 x 21 feet was 

 occupied by eight scabby sheep for 18 days. The kraal was then 

 again quarantined for 16 days, and then two sheep and one goat were 

 put into it for 38 days. All three animals remained clean. 



A closed corrugated iron shed 9 x 10 x 12 feet was occupied 

 by eight scabby sheep for 18 days, and then left empty for 16 days. 

 Two clean sheep were then put into it for 38 days, and remained free 

 of infection. 



The last experiment was the one carried out in Somerset East in 

 collaboration with the Division of Sheep. Two scabby sheep were 

 left in a closed brick stable measuring 6 x 12 x 12 feet for 84 days. 

 The Somerset East Agricultural Society was particularly keen that 

 a closed stable should be used instead of an open kraal. It was 

 suggested that the former would retain the infection much more easily 

 than the latter. After removal of the two scabby sheep the stable was 

 left empty for 16 days, and was then occupied by two clean sheep for 

 47 days. At the end of the experiment, these two sheep were found 

 to be free of scab. 



It may be added that all these kraals or sheds contained some 

 6 inches of manure, and in addition logs covered with bark and stones 

 were used in the second and third experiments, to afford as much 

 protection as possible to the scab parasites. Furthermore, infected 

 wool and crusts were taken from the scabby sheep on the day they 

 were removed from the kraal and deposited in the latter, so as to 

 ensure a heavy infection. Nevertheless, as can be seen from the 

 above results, no single animal picked up the infection on being put 

 in the kraals after a period of 16 days. 



We can therefore safely assume that the results originally ai^ived 

 at by Shilston and Bedford were correct, and that if scabby sheep be 

 taken out of a kraal, shed, or stable, and the latter left empty for 

 16 days, there will be no danger of reinfection if clean sheep are put 

 back into this enclosure after this period. 



