22 



DISEASES DUE TO PROTOZOA 



Africa. — Tripoli, Sudan, ^^>st Coast, Congfo State, Angola, 

 Uganda, Rhodesia and Madagascar. 



Asia. — Malay Peninsular, Assam, Upper Burmah. Siani, Java, 

 Batavia, Philippines and Ceylon. In Ceylon the average admitted per 

 annum over lo years was 3,500. 



America. — West Indies, British Guiana, \>nezuela, Colombia, 

 Brazil. Some of the Southern United States. 



Australia.— North Australia, Samoa, New Hebrides, Xew Cale- 

 donia, Fiji, New Zealand and Tasmania. 



THE CAUSATIVE AGENT. 



The organism is a spirillum, the Treponema perlenuis (Castellani, 

 I905)> 18 to 20 /J, long, with six to twentv fine uniform coils as shown 

 by Leishman's stain (for five minutes, tlien with water admixed and 



stained for one to four hours). It is more 

 difficult to stain than T. pallidum; the 

 difference between the two must be based 

 on biological tests. 



Its presence is constant in the primary 

 lesion or '" mother yaw " and in the un- 

 broken papules of the general eruption. 

 It is also found in the spleen, lymphatic 

 glands and bone marrow. It has not yet 

 been seen in the blood, but its presence 

 is certain, because when monkeys are 

 injected with blood from an infective 

 person it will develop typical yaw lesions. 

 It has not been found in the C.l^. fluid or 

 the tertiary lesions. 



Treponema fericuiic. (After 

 Castellani and Chalmers.) 



Multiple infection of the ulcers is very speedy 



HISTOPATHOLOGY. 



The surface epithelium is greatly thickened over the site of the 

 papules. The corium is the site of a marked oedema. 



There is an infiltration by millions of plasma cells; as a matter of 

 fact, there is nothing else (Macleod). 



There is no perivascular mononuclear infiltration as in Syphilis, 

 or any endothelial proliferation in the vessel walls. 



Giant cells are absent, but they are present in syphilitic lesions. 



A well-marked hyperkeratosis is seen. 



The parasite is chiefly found in the epithelial layers (after Leish- 

 man's stain). 



