Nagana (Trypanosoma bnicei) 233 



NAGANA {TRYPANOSOMA BRUCE I) : THE COURSE 



OF THE DISEASE IN LABORATORY ANIMALS 



WHEN INJECTED WITH CULTURES 



GROWN IN VIVO AND IN VITRO. 



Charles A. Behrens\ Purdue University. 



Nagana, or Tsetse fly disease, as it is correctly called, is due to 

 a specific trypanosomal parasite. It occurs naturally in many parts 

 of Africa, and its causative agent, which was discovered by Bruce in 

 1894, bears the scientific name of Tiyanonomd brucei. 



Normally the parasite exists in the blood of certain animals which 

 apparently have a marked tolerance for it, thus serving as its natural 

 source of infection. 



Most mammals are susceptible to Nagana with the exception, how- 

 ever, of man. The parasite can easily be perpetuated in vivo by resorting 

 to the ordinary laboratory methods of inoculation. And also since the 

 trypanosome can be cultivated in vitro upon blood agar medium, as 

 Novy and MacNeal' first demonstrated in 1903, it lends itself ideally 

 for experimental work. It is very interesting not only because it is 

 a disease of distant Africa and due to a special type of parasite, but 

 also because of the fact that it gives to a trypanosomiasis occurring 

 in very distinct forms depending primarily upon the species of the animal 

 and the virulence of the organism. 



The source of the strain of Trypunosoma brucei used in our experi- 

 ments is from an infected dog sent by Bruce to England in November, 

 1896, and it was this parasite which Novy and MacNeal used in their 

 cultivation experiments." 



There are three distinct varieties of the disease: 



First, the acute type which occurs in the rat, mouse, field mouse 

 (Arvicola), marmot, hedgehog, dog, cat, squirrel and monkey. 



Second, the subacute type which develops in the rabbit, guinea-pig, 

 field mice {Miia sylvaticus, Arvicola arvalis) , garden mouse {Eliomys 

 quercimis) , eriuine, and pig. 



Third, the chronic variety which occurs in cattle, goats, sheep, geese 

 and fowls. 



Table I lists some of the animals susceptible to Nagana. 



In an acute infection, the trypanosome makes its way into the blood 

 in from one to several days. Following this infection the number of 

 parasites usually increase constantly and regularly until the death of 

 the host, which may occur in a few days, or a week, or even longer. 



The subacute course of the disease is quite different for while the 

 parasites do not appear in the blood as soon as in the acute form their 

 development is not rapid and continuous for they may practically dis- 



' Contribution from the Bacteriological Laboratory, Purdue University, Lafayette, 

 Indiana. 



= Jour. Amer. Med. Assn.. 1903, 41, p. 1266; Jour. Infect. Dis., 1904, 1, p. 1. 



^ This work was made possible through the kindness of Dr. F. G. Novy, Professor 

 of Bacteriology, University of Michigan, from whom trypanosomal blood was obtained. 



"Proe. 38th Meeting. 1922 (1923)." 



