so 



THE HEMOFIAGEXLATES 



ment or slaughter of all affected animals 

 and periodic mass prophylactic treatment 

 of all animals. The latter is discussed in 

 the section on treatment of T. congolense. 



Fly traps and fly repellents have been 

 used without much success in attempting 

 to control tsetse flies. Elimination of 

 breeding places has been practiced on a 

 wide scale in many areas. Since the tsetse 

 flies breed under brush along streams or 

 in other localities, such measures consist 

 essentially of brush removal. Two meth- 

 ods are used: 



Eradicative clearing aims at eradica- 

 tion of tsetse flies thruout an area. All 

 the species of trees and shrubs under which 

 the flies survive thru the dry season are 

 removed. When this is done thoroughly 

 over a large area, the flies disappear com- 

 pletely. 



Protective clearing is more limited. 

 It is designed to break the contacts between 

 tsetse flies and domestic animals and man 

 at the places where transmission is taking 

 place. Fly-free belts wide enough so that 

 the flies cannot cross them are established. 

 In addition, inspection stations known as 

 deflying houses may be set up on traffic 

 routes to remove flies which may be car- 

 ried across on vehicles or animals. 



Bush clearing can be quite successful. 

 The incidence of trypanosomosis was re- 

 duced by 92% between 1938 and 1944 in the 

 Kamba area of Africa by this means 

 (Morris, 1946). However, it is expensive, 

 requires a large amount of labor, and the 

 initial clearing must be followed up faith- 

 fully as new growth occurs. 



A potentially much more satisfactory 

 control measure is the spraying of insec- 

 ticides on fly breeding places by means of 

 aircraft. DDT and benzene hexachloride 

 are highly effective for this purpose. 

 Glossina pallidipes was eradicated from 

 Zululand by airplane spraying with these 

 insecticides at a total cost of 2. 5 million 

 pounds, or slightly less than 2 shillings 

 per acre (DuToit, 1959). 



Since tsetse flies bite only in the day- 

 time, night grazing has been practiced by 



African natives to avoid their bites. The 

 animals are held in a protected corral 

 during the day. 



Cattle can be sprayed with DDT or 

 another insecticide in order to kill any 

 tsetse flies which light on them. 



The elimination of reservoir hosts, 

 e. g. , wild game in Africa, has been ad- 

 vocated and practiced in some regions 

 despite the protests of many people inter- 

 ested in game preservation. The Trypan- 

 osomiasis Committee of Southern Rhodesia 

 (1946) has described and defended the prac- 

 tice. It claims that if a zone 10 miles 

 wide with its ends in fly-free country is 

 fenced off and all the game within it is 

 killed, Glossina morsitans will disappear 

 in less than 10 years. The fences can 

 then be removed and the game allowed to 

 return into the area. 



Since trypanosomes can be transmitted 

 mechanically by inoculation of infected 

 blood or lymph, there is danger of its 

 transmission by the use of contaminated 

 instruments in bleeding, castrating, etc. 



A great deal has been written on try- 

 panosomosis control. For further infor- 

 mation, see Hornby (1949, 1952), Morris 

 (1946), Buxton (1948, 1955) and the pro- 

 ceedings of the meetings of the International 

 Scientific Committee for Trypanosomiasis, 

 which held its sixth meeting in 1956. 



TRYPANOSOMA GAMBIENSE 

 DUTTON, 1902 



TR Y'PANOSOMA RHODESIENSE 

 STEPHENS AND FANTHAM, 1910 



These two species cause African 

 sleeping sickness in man. T. rliodesiense 

 is thought to occur also in antelopes 

 (Hoare, 1955) and was isolated once from 

 a bushbuck (Heisch, McMahon and Manson- 

 Bahr, 1958). T. ganibiense does not occur 

 in wild game. Neither occurs in domestic 

 animals. They are morphologically indis- 

 guishable from each other and'from T. 

 brucei, and for this reason some people 

 prefer to consider all three as subspecies 

 of T. brucei. However, the biological and 



