270 SURRA 



The temperature for the first few days ranges from 104° to loj'^ F., 

 the pulse is full and strong. This may be termed the acute stage. Then 

 begins an asthenic state, which may terminate fatally within a variable 

 period, or by a slow convalescence. During this stage, usually within lo 

 daj's after the onset, there appears a commencing oedema above the 

 belly, involving the soft parts, coincident with this, or soon after, the 

 tedema extends to the feet and legs. The pulse becomes rapid, weak 

 and dichrotic, the respiration increased, shallow and jerky, the gait 

 staggering. Emaciation is rapid and extreme. 



The disease has a tendency to relapse, this may occur at any time, 

 even after convalescence appears to have been fully established. The 

 relapses are invariably fatal. 



The mortality in this epidemic has been about 75 per cent for Ameri- 

 can horses and mules, and 100 per cent for native ponies. 



The gross pathology shows serous effusions into the pleurae, peri- 

 cardium, and sometimes the peritoneum. There is also a serous exudate 

 into the cellular tissue of the legs and abdomen. The organs are pale, 

 but otherwise normal in appearance. 



At the time of our inspection, five acute cases w-ere examined, the 

 duration of the attack being from six days to two weeks. All these 

 animals presented the several clinical appearances as above described. 



Blood specimens were taken from the jugular vein of each and 

 examined microscopically, shortly afterwards. In 4 of these a parasite 

 was demonstrable. The other was negative, but a specimen taken the 

 following day showed the presence of this same parasite. 



On the day following, specimens were obtained from 12 others, all 

 chronic cases, with the result of finding this same parasite in the blood 

 of four. In three they were very few, whilst in the fourth, the}- were 

 present in great numbers, as many as 20 could be seen in one microscope 

 field. The animal from which the specimen was taken had suffered a 

 relapse. 



It would appear that the parasite may disappear from the peripheral 

 circulation, or exists there in such few numbers that it is not easily 

 demonstrable, after the acute stage has passed, it would require repeated 

 blood examinations to decide this point. 



Description of the parasite. The parasite resembles a whiplike 

 worm, having much the appearance of the Trichocephalus Dispar, its 

 length is from 10 to 14 mikrons, and is from i. to 1.2 mikrons in diameter 

 through its body, the neck is nearly h its length, tapering graduall}- to 

 a point representing the mouth (?). It has a limiting membrane, which 

 is well defined, the contour is in most cases, symmetrical, but in some 

 the body line is quite irregular. The larger part of the parasite (body) 

 contains granular material and clear spaces, which latter vary in size and 

 number; they are irregularly distributed, and may encroach on the wall 

 so as to cause irregular outline. The granular material does not extend 

 to the neck. 



