SYMPTOMS 403 



transferring the virus from infected to non-infected animals is 

 by means of insects, especially the biting flies. Of the flies, 

 the tsetse-fly {G/ossina morsita^is^ is reported to be the most 

 important. Musgrave and Clegg conclude concerning the role 

 played by flies in transmitting this disease that "it has thus 

 far been conclusively shown that the tsetse-fly {^Glossina 

 morsitans^, at least one other variety of Glossini, Stomoxys 

 calcitrans, Musca brava (f), Taon, and at least one variety of 

 Tabani transmit the virus. All other biting insects have 

 been looked upon with suspicion, but absolute proof of trans- 

 mission b\' them has not been furnished." The theory as to 

 the method of transferring the parasite is that it is purely 

 mechanical, although some have thought the Trypanosoma 

 passed through one phase of its life cycle in the fly. 



The spread of the disease from one locality' to another is 

 caused by the introduction of animals carr3ang the parasite. 



§ 314. Symptoms. The symptoms as given by Lingard 

 are as follows: "The chief symptoms are the occasional 

 appearance of an urticarial eruption, generalized or localized, 

 closely following the first rise of temperature, but which may 

 make its appearance at any time during the course of the 

 disease ; then the presence of petechiae on the mucous mem- 

 branes, chiefly that covering the membrana nictitans, lachr\-- 

 mation and the exudation of a semi-gelatinous material into 

 the subcutaneous and other connective tissues. There is rapid 

 wasting and great weakness, although in the majority of cases 

 the appetite remains good throughout., no matter how high 

 the fever. There is extreme pallor of the visible mucous 

 membranes, and this is followed at a later period by yellow- 

 ness. From first to la.st there is progressive anemia ; the 

 blood at first presents a normal character, but after a varying 

 period of time it undergoes marked changes. The white cor- 

 puscles are increased in number and the red corpuscles usually 

 cease to form normal rouleaux, lose their individuality and run 

 together forming irregular masses. They are at first dark, 

 but gradually, as the disease advances, almost entirely lose 

 their coloring matter and become pale." 



