15B Journal of the Department of AGRicULTtiRE. 



possess dipping tanks, and saving the cattle once the disease has broken 

 out is the first and immediate object, another and temporary plan may 

 be adopted by shifting the cattle from the infected to a non-infected 

 area through a quarantine camp where sucli is obtainable. For this 

 purpose it is advisable to bring the cattle first on a portion of clean 

 ground sufficiently large to contain grazing for about thirty days. 

 This area should be divided into two portions. The cattle are brought 

 on to one portion and the disease will appear in the already infected 

 animals and these will drop ticks — new animals can only become 

 infected after the ticks have moulted. Accordingly we move the 

 cattle into the second clean portion before the ticks have moulted, 

 viz., after eighteen days. The disease will now beconie less evident 

 and only appear in a few animals ; these again will drop infected 

 ticks. Accordingly the movement must be made before they have 

 moulted, viz., after another eighteen days. The cattle can now safely 

 be moved into the clean area. In a period of one month all infected 

 cattle will have developed the disease and can be destroyed or removed 

 back to the infected veld. With the help of a thermometer the 

 disease can be recognized at an early date, infected animals showing 

 high temperatures. By removing sick animals at an early date the 

 risk of infecting the quarantine g*round is greatly reduced. It is 

 understood of course that subsequently cattle are not to graze over 

 the infected area for a period of at least fifteen months, during 

 which time the infected ticks will have died out, or if grazing over 

 the infected area is contemplated, the erection of a dipping tank 

 and the introduction of short interval dipping are necessary. 



Heartwater. — If we want to trek out of a heartwater-infected 

 area for the purpose of saving the stock not yet infected two ways 

 are open, depending upon what ground is available and whether such 

 ground is infected with bont ticks. Moving out of the infected area 

 into ground where no bont ticks are present means that the disease 

 must stop. This has been the experience of many bush veld farmers 

 who, with their stock, went down to the low country, and when 

 troubled with heartwater simply moved back again to higher-lying 

 ground. The fact was known for a long time, but the explanation 

 could not be given since no connection between tick and disease was 

 surmised. If, however, ground free from bont ticks is available then 

 the same procedure can be resorted to as explained in the case of East 

 Coast fever, i.e. moving on to a place which is known to be free of 

 heartwater, remaining there just over the incubation period of the 

 disease and moving out of it before the ticks which dropped have 

 moulted and are capable of attaching themselves, for which purpose 

 two quarantines of three to four weeks each will be sufficient. 



Eradication of diseases in ivhich the animal acts as a virus 

 reservoir. — The diseases which are maintained in the recovered 

 immune animals are biliary fever in horses and dogs, redwater and 

 the gall-sickness in cattle. As already stated the ticks which drop off 

 such animals are infected, both maintain the infection, and new- 

 susceptible animals introduced contract the disease in a virulent 

 form. Hence it is not possible to eradicate these diseases without 

 eradicating all tick-life. It is, liowever, possible to save stock. This 

 can be done bj^ dipping. As pointed out before, in the case of East 



