THE HEMOFLAGELLATES 



53 



emetic, which has been largely superseded 

 in other animals, is still used in treating 

 surra in the camel; a single intravenous 

 injection of 200 ml of a 1% solution is 

 given. This drug is also widely used in 

 cattle in India because of its cheapness. 



Control : Essentially the same meas- 

 ures used in the control of T. brncei. ex- 

 cept of course those directed against the 

 tsetse fly, can be used in the control of 

 T. evansi infections. Control of horse- 

 flies and other biting flies is important. 



Remarks : Hoare (1956, 1957) has 

 discussed the phytogeny of T. evansi. 

 This species undoubtedly arose from T. 

 briicei, being introduced into camels when 

 they entered the tsetse fly belt and then 

 becoming adapted to mechanical transmis- 

 sion by tabanids. 



TRYPANOSOMA EQUINUM 

 VOCES, 1901 



This species occurs in South America, 

 where it causes a disease known as mal de 

 Caderas in horses. The disease is similar 

 to surra. T. equimim differs morpholog- 

 ically from T. evansi only in lacking a 

 kinetoplast. However, strains of T. evansi 

 without a kinetoplast have appeared in the 

 laboratory, and T. eqidnuni undoubtedly 

 originated in this way. 



T. equimim is transmitted mechan- 

 ically by tabanids. Both antrycide methyl 

 sulfate and suramin can be used in treat- 

 ing it. The former is less toxic. A single 

 subcutaneous dose of 5 mg/kg or less of 

 antrycide methyl sulfate or a single intra- 

 venous dose of 4 g per 1000 lb body weight 

 of suramin can be used. Control measures 

 are the same as for T. evansi, 



TRYPANOSOMA EQUIPERDUM 

 DOFLEIN, 1901 



'I'his species is morphologically indis- 

 tinguishable from T. evansi. It causes a 

 disease of horses and asses known as 

 dourine. This is a venereal disease, 

 transmitted by coitus. Dourine is similar 



to nagana, but runs a more chronic course 

 of 6 months to 2 years. The incubation 

 period is 2 to 12 weeks. 



The first sign of the disease is edema 

 of the genitalia and often of the dependent 

 parts of the body. There is slight fever, 

 inappetence, and a mucous discharge from 

 the urethra and vagina. Circumscribed 

 areas of the mucosa of the vulva or penis 

 may become depigmented. 



The second stage of the disease, 

 characterized by urticaria, appears after 

 4 to 6 weeks. Circular, sharply circum- 

 scribed, urticarial plaques about 3 cm in 

 diameter arise on the sides of the body, 

 remain 3 or 4 days, and then disappear. 

 They may reappear later. Muscular pa- 

 ralysis later ensues. The muscles of the 

 nostrils and neck are affected first, but 

 the paralysis spreads to the hind limbs 

 and finally to the rest of the body. Inco- 

 ordination is seen first, and is followed 

 by complete paralysis. Dourine is usually 

 fatal unless treated, altho mild strains of 

 the parasite may occur in some regions. 



T. equiperdum is found in Asia, North 

 and South Africa, southern and eastern 

 Europe and the U. S. S. R. It was once 

 common in western Europe and North 

 America, but has been eradicated from 

 these regions. The last place where it 

 was known to occur in North America, the 

 Papago Indian Reservation in Arizona, was 

 released from quarantine in 1949. 



Dourine can be diagnosed by finding 

 the parasites in smears of fluid expressed 

 from the urticarial swellings, lymph, the 

 mucous membranes of the genitalia or 

 blood. The signs of the typical disease are 

 characteristic enough to permit diagnosis 

 in endemic areas. Inoculation of mice, 

 rats, rabbits or dogs may also be prac- 

 ticed, but it is often difficult to demonstrate 

 the parasites on the first passage. The 

 complement fixation test is invaluable in 

 detecting early or latent infections, and it 

 was only by its use that dourine was erad- 

 icated from North America. All horses 

 imported into the United States must be 

 tested for dourine before they are ad- 

 mitted. 



