Surra: Rot. 587 



I/ingard finds another bearer in the crow which sits on the 

 backs of affected horses, pecking at the wounds, and passes at 

 once to other healthy horses to peck their sores. 



Experiments in feeding the infested blood to sound animals, 

 have apparently succeeded, and the observation that dogs and 

 cats suiTer from eating the carcasses is in favor of this view. 

 Horses that lick the infested sores, or the blood drawn by the 

 flies may readily infect themselves, and especially if the mouth 

 bears .scratches caused by fibrous food, leech bites, or sores from 

 bits, or if the pharynx or stomach has been wounded by bots or 

 spiroptera. 



The water and food are blamed b)' the natives in some quar- 

 ters, but Pease's observations on the Bombay tramway honses, 

 which all perished though kept on boiled water and carefully 

 picked fodder from sound regions, would suggest that this if a 

 channel of infection at all, is not the main one. 



The bowel excretions of rats harboring trypanosoma, when 

 mixed experimentally with the food of the lior.se, have been 

 charged with causing surra, but there are objections to the ac- 

 ceptance of this as a common cause. The alleged period of incu- 

 bation in the horse in such cases was 40 days in place of the 

 usual 7 or 8 days, when inoculated from a horse first affected in this 

 experiment on a second the usual incubation of 7 or 8 days was 

 shown, and though the horse fed on rat'sdung in the infected region 

 of Bombay contracted the disease, the experiment failed when the 

 same dung was fed in a high dry region unaffected by surra. 

 The natural inference is that Bombay experimental horses con- 

 tracted the affection in the usual way, probably through insects. 



In the rainy season the Indian rats swarm with the Trypanosoma 

 lyewisi, an entirely different species, and though they can be suc- 

 ces.sfully inoculated with the T. Evansi of Surra, the T. Equiper- 

 dum of Dourine, the T. Brucii of Nagana, and it is alleged the 

 T. Equinum of Mai de Caderas, yet these are not their common 

 parasite. The presumption is that the rat affected with Trypano- 

 soma Evansi could transmit the disease to the horse through one 

 of the many possible insect channels or otherwise. 



Neither condition, sex nor age appears to affect receptivity. 

 Open sores especially open the way for infection. 



The position of stables, yards, pa.stures or picket grounds near 

 stagnant water, manure or rubbish heaps, abattoirs or other 



