I TRYPANOSOMA 47 



(Stomoxys) — though this has not so far been absolutely determined. 

 The disease occurs from India to the Malay Archipelago and the 

 Philippines, and in various parts of Africa, while destructive epi- 

 demics have been caused by its being carried to Mauritius and 

 Australia. 



T. equinum causes the disease known as •' Mai de caderas " which 

 occurs in the form of very destructive epidemics amongst the horses 

 of Paraguay and adjoining regions of South America. Dogs are also 

 afEected, as well as Tapirs, Carpinchos (Capybaras) and other wild animals. 

 Nothing is known as to the mode of transmission. 



T. equiperdum, the cause of the disease known as " Dourine " among 

 breeding horses round the shores of the Mediterranean, differs from the 

 trypanosomes hitherto described in being transmitted directly from one 

 individual to another by sexual contact. 



T. lewisi is of interest as being the trypanosome most easily obtained 

 for purposes of study in most civilized countries. It is practically 

 world-wide in its distribution and is to be found in the blood of Rats, 

 especially of young individuals. The intermediate hosts are parasitic 

 insects — especially fleas of various species. 



T. gambiense was first observed in 1901 by Forde in the blood of a 

 patient supposed to be suffering from malarial fever in the neighbourhood 

 of the River Gambia. To this new trypanosome the name T. gambiense 

 was given by Datton. Other cases were observed and it was recognized 

 that there existed a definite disease — " Trypanosome fever " — distinct 

 from ordinary malaria. Just about the same time a deadly epidemic 

 had been ravaging the native population of Uganda — a peculiar disease 

 which had long been known on the West Coast as sleeping sickness from 

 the drowsy lethargic symptoms of its later stages. A Commission was 

 sent out by the Royal Society to try and find out the cause of the disease 

 as a preliminary to the devising of means for its prevention or cure. In 

 April 1903 a member of this Commission — Castellani — found a trypano- 

 some in the cerebro-spinal fluid of a sleeping-sickness patient and at 

 once suspected that this was the microbe which caused the disease. 

 Bruce and his colleagues on the Commission confirmed Castellani's 

 discovery and amplified it by discovering that the trypanosomes were 

 invariably present in the blood of sleeping-sickness patients, while in the 

 later and more typical stages of the disease they were present also in 

 the cerebro-spinal fluid. The earlier stages of the disease were found 

 in fact to be identical with " Trypanosome fever." 



Bruce, the discoverer of the cause and means of transmission of 

 Nagana, being a member of the Commission the suspicion naturally 



