Course and Prognosis. 831 



finally the disease passes into the aggravated condition which 

 leads to a fatal termination. 



In southern regions the disease appears to run a more 

 acute course, so that the patients may die after 1 to 2 months 

 and even inside of 6 to 8 days (Monod). At the same time 

 the febrile attacks are more conspicuous following each other 

 in more rapid succession, and the paralytic symptoms also de- 

 velop more rapidly, therefore there are no marked, and es- 

 pecially no chronic interstitial changes of the nerves in the dead 

 animals. 



The termination of the disease varies in different outbreaks. 

 While sometimes about half of the affected animals die (in 

 India, according to Pease, the mortality amounts to 70-80%), 

 in other cases the loss is much smaller (thus for instance in 

 A.-Vadasz and vicinity, out of 30 mares in which the disease, 

 was established with certainty only two died). Eecovery is 

 possible even after the appearance of the nervous symptoms, 

 dollar spots and paralysis, and such animals may then perform 

 hard work for years. It is probable that in some cases only 

 the local changes of the genitals develop after an infection, 

 which definitely heal without the later development of nervous 

 symptoms. 



Some authors are of the opinion that the disease develops 

 more rapidly in stallions and that it runs a more unfavorable 

 course than in mares, and in Algeria it is supposed to limit 

 itself in asses in the majority of cases to a local affection of 

 the genital apparatus. 



Diagnosis. In northern regions where dourine apparently 

 represents the only trypanosome affection of solipeds, the 

 diagnosis is definitely established by the demonstration of 

 trypanosomes ; but this is associated with considerable difficulty, 

 as the parasites are present but rarely in the blood, and even 

 then only in very small numbers. Their occurrence in the 

 serous fluid of the dollar spots, especially immediately after 

 these appear, is more constant, as is also the case in the edema- 

 tous swellings in the vicinity of the external genital organs, 

 but even here the examination requires great patience. Their 

 demonstration in the mucous secretion of the urethra and 

 vagina is much easier (Fig. 149), but even there it is to be 

 remembered that they may disappear periodically from the 

 secretion. 



A sufficient quantity of secretion is obtained from the vagina by scraping the 

 mucous membrane with a scalpel or with a glass slide. In stallions the penis is 

 drawn out with the left hand, and then a long-handled, bean-shaped, oval spoon 

 with dull edges is introduced into the urethra, with which the mucous membrane 

 is scraped off. 



In doubtful cases blood may be injected subcutaneously into dogs. In the 

 swellings which subsequently develop trypanosomes are always present in great num- 

 bers (Buffard & Schneider). Mice may also be used for this purpose. Since the 

 material is frequently non-pathogenic for test animals, even from horses positively 

 affected with dourine (see p. 817), only a positive result of the inoculation has 

 a diagnostic significance. 



