460 GENERAL DISEASES. 



weaker and weaker and finally die from debility after a variable 

 period of suffering which may extend from a few weeks to tv/o 

 or three months. Bruce, who lias investigated nagana (Zulu, 

 depressed in spirits) in its native abode, considers it to be 

 surra; as the microbes of both appear to be almost if not 

 quite identical, and the principal symptoms are the same. Lin- 

 gard found that the microscopical appearance of the flagellated 

 infusorian of nagana is exactly similar to that of the surra 

 microbe. The only difference between the two seems to be that 

 horned cattle are susceptible to the " fly," but are nearly im- 

 mune from surra. Bruce regards this comparative immunity as 

 a peculiarity of Indian cattle, which, if his theory be correct, 

 resemble Algerian sheep (p. 18) in their freedom from anthrax. 

 Dogs are attacked by both diseases. Theiler (" Vet. Record," 

 1st March, 1902) tells us that the dog is the most susceptible 

 animal and the one in which the illness runs the quickest course. 

 Bruce has found that " the fly " is in no way virulent of itself ; 

 but that it acts simply as a carrier of the disease germ. " The 

 fly" disease proves fatal to all meimbers and hybrids of the horse 

 family except zebras. 



Theiler states that the tsetse fly is dependent for its existence on 

 big game, in the blood of which, Bruce frequently found trypano- 

 somata (the microbes of this disease) ; and that the more big game 

 are pressed back by the advance of white men, the more the disease 

 disappears. 



Recent researches show that human beings are liable to be 

 affected by a disease closely akin to surra and nagana, as we may 

 see from the following extract from " The Lancet" of 11th January, 

 1902, concerning a case of trypanosomatosis in a European, which 

 came under the observation of Dr. J. E. Dutton on the Gambia : — 



" The preparation reveals typical trypanosomata, few in number. 

 The account of the case shows that the patient has been suffering 

 from a form of relapsing fever with peculiar oedema of the eyelids 

 and puffiness of the face, also oedema of the legs, general weakness, 

 abnormal frequency of pulse and of respiration, and enlarged spleen. 

 There was no organic lesion of the heart and kidneys, and no 

 malarial parasites were found after repeated examination. The 

 relapsing fever recalls that of horses suffering from the same para- 

 site. It is not yet certain whether the parasite approximates to 

 T. Brucii or to T. Lewisi." 



SYMPTOMS AND POST-MORTEM APPEARANCES.— " The 



clinical symptoms of nagana are little typical. Advancing anaemia 

 and hydrsemia run concurrently with emaciation. There is oede- 

 matous swelling of the deeper parts of the rump and other 



