THE HEMOFLAGELLATES 



49 



cause. It is due to the destruction of red 

 cells with consequent release of potassium 

 into the plasma, and the observed levels 

 are not too harmful. 



Epidemiology : The epidemiology of 

 the diseases caused by T. briicei and other 

 tsetse-borne trypanosomes depends upon 

 the bionomics and distribution of their 

 vectors. This is such a vast subject that 

 no attempt will be made to cover it here. 

 In general, tsetse flies occupy almost 4 

 million square miles of Africa. They 

 occur in woodlands, bush or forested areas 

 where there is ample rainfall and where 

 the mean annual temperature is above 

 about 70° F. Not all species are good vec- 

 tors, and trypanosomosis does not occur 

 every place that tsetse flies do. For fur- 

 ther information on tsetse flies and the 

 epidemiology of trypanosomosis, see 

 Buxton (1948, 1955, 1955a), Hornby (1949, 

 1952), Davey (1958) and Ashcroft (1959). 



Diagnosis : In the acute or early stage 

 of the disease, trypanosomes can be found 

 in the peripheral blood. Thick blood 

 smears are preferable to thin ones. The 

 protozoa are found even more often in the 

 lymph glands. They can be detected in 

 fresh or stained smears of fluid obtained 

 by puncture of the glands. In the later 

 stages of the disease, trypanosomes can 

 be found in the cerebrospinal fluid. Lab- 

 oratory animals such as the rat can also 

 be inoculated. The complement fixation 

 test can also be used; it is not specific 

 for T. brucei infections, but also reacts 

 in a number of other trypanosomoses. 



Cultivation : Trypanosomes can be 

 successfully cultivated in a number of 

 media. A common one is NNN medium, 

 which is essentially a 25% blood agar 

 slant. Another medium is that of Weinman 

 (1946), which contains beef extract, pep- 

 tone, washed erythrocytes and plasma. 

 Still another is that of Tobie, von Brand 

 and Mehlman (1950). A discussion of 

 problems of cultivation and diagnosis is 

 given by Weinman (1953). 



Trypanosomes can also be cultivated 

 in developing chick embryos or in tissue 

 culture. See Pipkin (1960) for a review 

 of this subject. 



Treatment : Many different drugs have 

 been used in the treatment of trypanoso- 

 mosis. Indeed, the first synthetic organic 

 compound of known composition ever used 

 to cure an experimental disease was try- 

 pan red, which was developed by Ehrlich 

 and Shiga (1904). Since that time thousands 

 of drugs have been found to show some ac- 

 tivity, but the number of satisfactory ones 

 is very small. The chemotherapy of try- 

 panosomiasis has been reviewed by Findlay 

 (1950), Ing (1953), Browning (1954), Good- 

 win and RoUo (1955), Davey (1957), and 

 others. 



Altho much of the earlier work on 

 chemotherapy was done on members of 

 ihebyncei subgroup, most of that since 

 World War n on trypanosomosis of live- 

 stock has dealt with the vivax and coiigo- 

 lense groups. 



Antrycide methyl sulfate is perhaps 

 the drug of choice for T. brucei in horses. 

 It is injected subcutaneously at the rate 

 of 5 mg/kg body weight; two treatments 

 may be given 4 days apart. Antrycide is 

 also effective against T. brucei in dogs, 

 cattle and other animals. 



Suramin (Germanin, Naganol, Antry- 

 pol, Moranyl, Bayer 205, Fourneau 309, 

 etc. ) has been used for many years. A 

 single dose of 4 g per 1000 lb body weight 

 is given intravenously to horses, but it 

 may be toxic in some animals. In dogs, 

 5 mg/kg is given intravenously. 



The diamidines, pentamidine and 

 stilbamidine, have been used extensively 

 against T. ga)iibie)2se and T. rhodesiense 

 in man, but have been used very little in 

 veterinary medicine. Another diamidine, 

 Berenil, appears promising against T. 

 brucei, but needs more study. 



Control: Preventive measures 

 against trypanosomosis include measures 

 directed against the parasite, measures 

 directed against the intermediate hosts, 

 livestock management, elimination of 

 reservoir hosts, and avoidance of acci- 

 dental, mechanical contamination. 



Measures directed against the para- 

 site include continuous survey and treat- 



