DISEASES PECULIAR TO SOUTH AFRICA 1373 



taken for that disease; but each disease is distinct from the other, and 

 although Edington claims that horse sickness, gall sickness and veldt sick- 

 ness are only forms of one disease, the investigations of Kock, Theiler, the 

 late Mr. Hutcheon and others, have proved this to be a fallacy. Space, 

 however, will not permit giving the full result of their investigations. 



What To DOi Prevent the disease by careful attention, and by pro- 

 tective inoculation, and by not allowing the horse to eat dew-laden grass 

 until well dried by the sun. If possible, remove horses to higher veldt 

 where frosts prevail. If animals have to remain in districts infected with 

 horse sickness use nose bags (as illustrated on page 394) previously 

 steeped in some good antiseptic fluid. Put on before sun set and take 

 off after sun rise, thus preventing grazing and acting as an antiseptic. 

 Inoculation (protective) is by far the best method. Kock, Theiler and 

 others, have succeeded in giving immunity by inoculation, using both 

 virulent blood and antitoxic serum, and although the final stage of their 

 investigations have not yet been reached, they are sufficiently advanced 

 to give immunity for a short period. 



Blue Tongue (Blaauw Tong) (Bekziekte) 



or Malarial Catarrhal Fever of Sheep 



What It Is. Blue Tongue is an inoculable disease of sheep, character- 

 ized usually by fever and many definite symptoms, comprising, chiefly, 

 lesions of the mouth and feet. It is common in many parts of the Cape 

 Colony, Bechuanaland, British Protectorate and Transvaal. 



Prevaiencet The late Director of Agriculture, Cape Colony, long ago 

 pointed out that this disease was met with both on low and high veldt, 

 under conditions which were recognized as being also most favorable for 

 the production of horse sickness, but being much more prevalent and 

 wide spread than the latter, and occurring regularly every day in certain 

 localities. Less frequent in high altitudes than in low lying areas. The 

 fever season is well marked in many districts and generally lasts from 

 January to April. It is less prevalent in dry seasons and the cases that 

 do occur are of a much milder type ; and sheep that are kraaled high up 

 on a hill side rarely become infected. Outbreaks are said to cease after 

 the first frost. 



Mode of infection. It is generally believed that sheep suffer less from 

 Blue Tongue when their wool is long than when newly shorn, and this 

 is proved to a certain extent by the fact that when sheep are dipped in 

 any of the good dips, it has a checking influence in the number of cases 

 in an outbreak. This is probably due to the fleece becoming repellent, 

 after dipping, to such insects that carry the infection. Kraals situated 



