234 SECTIONAL ADDRESSES. 



is so successful that tlie disease has lost much of its terror since the 

 discovery of the value of this drug. 



In some of the other ' piroplasmoses ' (in the wider sense of the term), 

 no such simple treatment is available. As a matter of fact, in the case 

 of Anaplasmosis and East Coast Fever of cattle, no satisfactory method 

 of treatment is known. In these cases, therefore, prevention should be 

 aimed at. 



Various methods of preventive inoculation against Anaplasmosis have 

 been advocated. In South Africa Theiler, who originally described the 

 parasite {Anaplasma marginale) causing Anaplasmosis, found a second 

 species or variety {Anaplasma centrale) which differed from the first, not 

 only in regard to its relative position in the red blood corpuscle, but also 

 as regards its virulence. It was found that the injection of blood con- 

 taining Anaplasma centrale invariably produced a mild infection, even in 

 imported cattle, but that this infection conferred sufficient immunity to 

 protect animals against the fatal Anaplasma marginale infection. This 

 method of immunisation has been practised in South Africa for nearly 

 twenty years and has been the means of saving thousands of animals. 

 The Anaplasma centrale strain has also been sent to other countries where 

 the same method has been used with good results. 



Of the diseases mentioned in this section, East Coast Fever is the most 

 formidable because of the very high mortality attending it. This disease 

 must have cost South Africa several million pounds since its first appearance 

 nearly 30 years ago. The loss to the country has been partly direct 

 through the death of many thousands ot animals, partly indirect through 

 the costly organisation which it is necessary to maintain to fight the 

 disease. 



It is impossible in this brief review to discuss the methods employed 

 in the eradication of East Coast Fever, or the many practical difficulties 

 encountered in this campaign. For our purpose it is sufficient to state 

 that the dipping of cattle in an arsenical bath has proved to be a very 

 valuable aid in the fight against East Coast Fever or any other tick-borne 

 disease. 



In South Africa dipping has been practised since the beginning of this 

 century, and has now become an integral portion of the daily routine of 

 farming. No up-to-date stock farm can be found to-day without at least 

 one dipping tank. The dip was originally intended chiefly as a weapon in 

 the fight against tick-borne diseases, but to-day it is largely used merely 

 to keep the cattle free of ectoparasites, quite apart from the fact that some 

 of these parasites may be carriers of disease. The necessity of keeping 

 cattle free of ticks is obvious to anyone who has lived in a tropical or 

 semi-tropical tick-infested country. As an illustration, the fact may be 

 mentioned that on the Natal Coast, before the days of dipping, it was rare 

 to see a cow with more than one or two teats intact, and it was impossible 

 to raise more than about 30 per cent, of the calves ; whereas to-day, 

 thanks to the dipping tank, all the udders and teats of the cows are 

 healthy and it is nothing unusual to raise 95 per cent, or more of the calf 

 crop. Even if all the tick-borne diseases should now disappear, the 

 majority of farmers in South Africa would continue to dip their animals 

 regularly. 



