HUMAN TRYPANOSOMIASIS 137 



his work and believes that he is recovering. This con- 

 dition may last for two or three years. During this 

 period trypanosomes will only be found in the blood after 

 prolonged search : they may be more abundant during 

 a pyrexial period in those cases in which definite attacks 

 of fever recur. They are much more readily found in the 

 soft enlarged glands, but in old hard glands, though they 

 be still enlarged, the trypanosomes may not be more 

 numerous than in the peripheral blood. 



Orchitis occurs in some cases both from the Congo and, 

 more commonly, from Rhodesia, one or both testicles 

 may be affected, or alternately one and the other. 



Haemorrhages from the nose or gums may occur and 

 may be repeated. 



Iritis, keratitis or retinal changes may occur in untreated 

 cases, and in cases treated by arsenic cataract, optic 

 atrophy, and other changes considered to be due to that 

 treatment, are common. Keratitis in the lower animals 

 resembles the interstitial keratitis of syphilis, and the 

 lesions are similar on microscopical examination. 



Injections of considerable amounts, 2 c.c. or more, of 

 the blood of such patients into monkeys or other sus- 

 ceptible animals will result in the infection of such 

 animals, and the trypanosomes can be found in number in 

 their blood, and the animals will die shortly after. Rats 

 may be infected in this way, but the results are uncertain, 

 and the period of incubation may be prolonged to 

 months. 



Sooner or later in a patient who may have been free 

 from fever, and in whom the presence of parasites may 

 anly be shown by the infection of animals with the 

 patient's blood, terminal cerebral symptoms supervene. 



The cerebral symptoms vary in character ; they may 

 take the form of a rapidly fatal coma or of a series of 

 epileptiform convulsions, or of the progressive lethargic 

 condition known as sleeping sickness or negro lethargy, 

 in some of its aspects, and in the pathological lesions not 

 unlike general paralysis of the insane. 



