574 FAMILY: TRYPAN0S0MID.1 



II. PATHOGENIC TRYPANOSOMES PASSED DIRECTLY FROM VERTE- 

 BRATES TO VERTEBRATES. 



Trypanosoma equiperdum Doflein, 1901. — Synonyms: T. rougeti Laveran 

 and Mesnil, 1901; Trypanozoon equiperdum {Luhe, 1906); Castellanella equiperdum 

 (Chalmers, 1918). 



Unlike other pathogenic trypanosomes, T. equiperdutn is transmitted 

 directly from animal to animal during the sexual act, as occurs with the 

 organism of syphilis. It produces in horses and donkeys a disease known 

 as dourine, which is endemic in various countries of Europe, in India 

 and probably other parts of Asia, in North Africa, North and South 

 America, and Canada. It was first named T. equiperdum by Doflein 

 (1901), and a few days later T. rougeti by Laveran and Mesnil, 



Symptomology. — The disease is usually of a chronic nature. The 

 first symptoms are noted about ten days or a fortnight after infection, 

 and consist of oedema of the sexual organs. About a month later charac- 

 teristic lesions in the shape of plaques appear on the skin. These vary in 

 size from that of a shilling to the palm of the hand. They are raised, and 

 give the impression of a hard subcutaneous disc. Each plaque may persist 

 for several days, or it may disappear in a few hours. A period of gradual 

 weakening and loss of flesh supervenes, accompanied by fever and pro- 

 gressive anaemia. Finally, paraplegia and various nervous symptoms 

 appear, and the animal dies in from two months to a year after infection. 

 The females usually abort during the course of the disease. Very rarely 

 recovery has taken place, after which the animals are immune to reinfection. 

 Sergent, Donatien, and Lheritier (1920) have shown that horses which 

 have entirely recovered as judged by disappearance of clinical symptoms, 

 either naturally or as a result of treatment, may still transmit the disease. 



Stallions which had acquired the disease were treated with atoxyl and 

 orpiment till complete clinical recovery had taken place. The animals were 

 then returned to full regimental duty, but the blood was examined from time 

 to time by inoculating dogs. The following history of four stallions is given : 



1. For a month after complete clinical recovery the blood still infected 

 dogs. During three years 3| litres of blood injected into nineteen dogs 

 failed to infect any. 



2. For a year after recovery 1|^ litres of blood failed to infect eight 

 dogs. Four months later one of two dogs injected became infected. 

 During the next two years 2 litres did not infect any of ten dogs. 



3. During two years 2-2 litres of blood did not infect eleven dogs. 

 During the third year, however, dogs were infected. 



4. During three and a quarter years 3-64 litres of blood did not infect 

 nineteen dogs. The blood then infected one of two dogs injected. 



