Etiology, Pathogenicity. 817 



According to Laveran & Mesnil the only distinguishing signs are 

 the sometimes pointed, at other times blunt, or sometimes split 

 posterior extremity, further in the parasites originating directly 

 from the horse, the absence of granulations is mentioned. 



Pathogenicity. Material containing trypanosomes taken 

 directly from horses is always virulent for horses, while it ap- 

 pears to possess for other animals a varying virulence, while 

 in Algeria, rabbits and dogs are usually infected very easily, 

 and a virus constantly effective for rats and mice was obtained 

 by further inoculations, similar material from horses in Hun- 

 gary proved pathogenic only for solipeds. During the last 

 invasion in Prussia, similar experiences were recorded, although 

 in some instances mice were successfully infected. Zwick & 

 Fischer then cultivated a strain by further passage through 

 mice with which they succeeded in infecting not only small test 

 animals, but also dogs, cats and sheep, and likemse goats and 

 cattle. 



Mares covered by stallions, the urethral secretions of which 

 contains trypanosomes, develop after about 2 to 4 weeks, some- 

 times even later, an acute inflammation of the vagina and an 

 edematous infiltration of the surrounding tissue, while later 

 ''dollar-spots" and still later sjmiptoms of paralysis appear 

 which continually become more intensive until the animal dies. 

 During the existence of the inflammation of the vagina, try- 

 panosomes may be demonstrated in the vaginal discharge, in 

 the edematous swellings and in the dollar-spots, much less fre- 

 quently also in the blood. An affected mare may also infect 

 the stallion, in which case the effects are first manifested in 

 an edematous swelling of the sheath and an accumulation of 

 mucous secretion in the urethra which contains trypanosomes. 

 The disease may also be produced artificially by smearing such 

 secretion or blood containing trypanosomes on the mucous 

 membrane of the vagina or urethra, as well as by dropping it 

 into the conjunctival sack. 



The injection of an emulsion of the spinal cord substance from an affected 

 horse, into the anterior chamher of the eye of a healthy animal, is also effective 

 (Nocard; Hutyra observed in a pony in such an instance the appearance of dollar 

 spots as early as in one week, and subsequently a rapid development of paralysis.) 



After the inoculation of virulent blood under the skin of 

 a horse an edematous swelling appears at the point of injection 

 in 7 to 12 days ; after 3 to 6 weeks transitory swellings of the 

 skin appear on different parts of the body, especially in the 

 vicinity of the genitals; after six weeks, sometimes not until 

 after five months, a paralysis of the hind parts develops with 

 knuckling of the hind legs, until the animal, which has become 

 greatly emaciated in spite of constantly good appetite, suc- 

 cumbs with symptoms of a lumbar paralysis. During the course 

 of the disease intermittent fever is observed. In some cases 



Vol. 1-52. 



