382 NAGANA 
NAGANA 
Synonym: Tsétsé-fly disease. 
Characterization. Nagana is a disease characterized by anemia 
and rapid emaciation caused by Trypanosoma brucei. It attacks 
horses, mules, zebras, cattle, and sheep. A number of the smaller 
animals are susceptible. It is known to all dialects as the tsétsé-fly 
disease. 
History. Livingston pointed out the existence of this disease in 
Central Africa. In 1886, Bruce studied it in the Zulu Land. He 
found constantly in the blood of the sick animals a trypanosoma simi- 
lar to that found in‘surra. It has been carefully studied by Kanthack, 
Durham and Blandford, Koel, Plimmer and Bradford, Theiler, 
Schilling, Laveran and Mesnil. 
Geographical distribution. This disease is found in central and 
southern parts of Africa. There seems to be some doubt about its 
identity with the disease of a similar nature in the Transvaal. 
Etiology. This affection is caused by Trypanosoma brucei. It 
is from 28 to 33y, in length with the flagellum and about 1.54. in width. 
It is closely related to Tr. equiperdum. Some investigators have been 
unable to satisfactorily differentiate the two species, while others 
recognize them as distinct. 
The trypanosomes are transmitted from the diseased to the healthy 
animals by means of the tsétsé-fly (Glossina morsitans), which exists 
in certain parts of Africa. It is suspected that other species of this 
genus transmit the trypanosoma. The affection is extended into 
uninfected areas by the introduction of diseased animals. 
The period of incubation, in artificially produced cases, is reported 
to be about 4 days in the horse. 
Symptoms. The first indication of the disease is a rise in tempera- 
ture which lasts for 3 or 4 days, when it suddenly drops. After this 
time the temperature oscillates between 35° and 41° C. Emaciation 
is rapid, the hair becomes rough and may fall out. There is a ten- 
dency to diarrhea. There is edema of the abdominal walls. In 
cattle the symptoms are not usually so acute as in the horse. 
The duration of the disease is said to vary from a week to six months 
or more. The appetite remains good until near the end. According 
to Bruce recovery is rare. 
