12 



ruvrVNOSOMlAHKH IN THE ANCi I.O-IUi VTTI AX STDAN 



Necessity for 

 a systematic 

 nomenclature 



Tliosu lyi>us possrss rcailily recoj;nisable morphological characteristics wliicii, at any 

 rate, enable one to differentiate positively between the four. 



It will be very apparent how desirable a system of general distinction is, when the 

 extent of tiie Anglo-Egyptian Sudan is considered, and when it is rcnioinbered tliat, owing 

 to natural conditions and geographical necessities, both animal and liuiuan life lias a 

 tendency to clump into diffuse and somewhat widely separated colonies or tribes. This 

 occasions not only the discovery of apparently isolated types of the disease, but undoubtedly 

 alters and influences the virulence and characteristics of trypanosomes whicli are of the 

 same stock. Unless some system be carried out, terms such as the " Trypanosomiasis of 

 Mules," "Trypanosomiasis of the ShiUuk Cattle" and "The Disease of the Camels of 

 Erkowit," come into existence, and, as they give no clue as to wliat the pathogenic agent 

 is, endless confusion is caused thereby. 



While it is admitted that morphological distinctions alone are not ideal or completely 

 adequate, yet they are of great practical utility in advancing towards intelligent 

 classification, rendering further separation an easy matter, thereby saving us from the 

 fallacies of identifying trypanosomes by their local hosts. The advance of the study of 

 these diseases has been to siiow that the connnunicability of the infection is less limited 

 than was at one time supposed, and that the restriction of a certain type of trypanosome to 

 one class of animal is due as largely to the existence of a suitable transmitting agent 

 as to the inherent refractory nature of the other animals. 



We may at this point take a concise review of our four types. 



Ti/pe 1. T. brucei or pecmuli, found on the Sobat and White Nile and in the 



Balir-El-Ghazal ; this trypanosome has been carefully investigated and reported on by 



Dr. Balfour in the Second and Third Reports, and the conclusion arrived at was 



that it most closely resembled what has been called the T. pecatidi of Senegal. 



Colonel Sir David Bruce, F.R.S., has, however, shown that, morphologically, it almost 



exactly resembles what he describes as T. brucei, a point more definitely considered in the 



second portion of this paper. Moreover, a comparison of the animal reactions shows few 



discrepancies. It is not intended here to discuss the position of T. pecaudi as to its 



specificity or otherwise, but it is obvious that it were better to include a doubtful 



Review of ihe trypanosome under the iieading of a large and well-recognised class than to place it with 



irypanosome smaller and less old established genus, should the reasons for placing it witli one or 



types "^ 



the other be in any way of equal weight. 



It has been suggested that a reason for regarding Type 1 as T. pecaudi is, that wliilu 

 horses, mules and donkeys are particularly affected on the White Nile and in the 

 Bahr-El-Ghazal, we have in these same districts herds of cattle belonging to the natives 

 which are, at any rate, so far unaffected that the natives can maintain them and breed 

 them in these regions, circumstances in some ways analogous with tlie occurrence of 

 " La Baleri," whose pathogenic agent has been called T. pecaudi. 



A brief consideration of a few points will show how fallacious a liasty suggestion 

 of this kind may be ; firstly, T. brucei produces a more chronic disease in bovidtc than 

 in equidic ; secondly, cattle are not entirely refractory to T. pecaudi ; thirdly, horses, 

 mules, etc., are animals of transport and travel in these countries, and of necessity must be 

 more liable to infection than the cattle wliicli the natives know how to keep in districts, 

 or parts of districts, where they are most likely to survive. Moreover, it is not impossible 

 to imagine that the cattle in these regions may have developed, in common with the wild 

 animals, a relative immunity or refractoriness to T. brucei. It is hardly necessary to enter 

 into any further considerations of this nature. 



