526 FAMILY: TKYPANOSOMID^ 



Pathology. — The lesions produced in man by T. gamhiense consist 

 of a hyperplasia of the lymphatic tissue of the body. There is enlargement 

 of the lymphatic glands and spleen. In the later stages the meninges 

 are affected, while there is an increase in the cerebro-spinal fluid. Most 

 marked are the changes about the arteries of the brain and cord, leading 

 to a thickening of the arterial coat, together with invasion of the area 

 around the vessel by round cells, which give rise to the characteristic 

 round-celled infiltration (Fig. 221, A). Mott (1899, 1906) pointed out that 









Fig. 221.— Section of Brain of Fatal Cases of Sleeping Sickness. (After 

 Stevenson, 1922 and 1923; from Tmns. Boy. Soc. Trop. Med. and Tlyg., vol. xi.) 



A. Perivascular infiltration by round cells (x200). 



B. Frontal lobe, showing two''trypanosomes in grey matter (x ca. 1,000). 



the lesions in sleeping sickness resembled those of general paralysis. As 

 a rule, in animals which do not live long after inoculation, these lesions 

 are not apparent, but in monkeys with long-standing infections, and even 

 in smaller animals if they survive for several months, the same round-celled 

 infiltration about the cerebral vessels can sometimes be demonstrated. 

 In sections of the tissues of man, trypanosomes are with difficulty found, 

 but their distribution in guinea-pigs infected with a strain of T. gambiense 

 from Nigeria has been studied by Stevenson (1917, 1918). Though present 



