MASTIGOPHORA 108 1 



other parts of Asia, and also in the Philippines and Northern Aus- 

 tralia. The Philippine outbreak was traced to animals returned 

 from China after the Boxer outbreak; for at that time American 

 troops came into contact with native Indian troops and their 

 animals. 



The trypanosome causing the disease was discovered by Evans 

 in 1880. The clinical course of the disease is marked by an irregular 

 recurring fever, with many remissions, during which the parasite 

 cannot be demonstrated in the blood, although it is not difficult to 

 find during the febrile period. The animal is anemic, weak, 

 emaciated, and may show an ecchymotic eruption on the abdomen. 

 The course of the disease may be either short or long, but leads 

 almost invariably to death. In camels it lasts from two to four years, 

 often without symptoms until near the end, and these animals prob- 

 ably act as chronic carriers. 



Morphology. Morphologically, the parasite is very like the Tryp- 

 anosoma brucei of Nagana, yet, as a rule, the trophonucleus lies nearer 

 the anterior end than in brucei, although it may be impossible to 

 distinguish in smears between the two. 



The disease is carried by biting flies, tabanidoe, and stomoxys, and 

 also by fleas. 



Trypanosoma brucei. Nagana is a well-known horse and animal 

 disease of Africa, which causes an enormous economic loss and has 

 greatly interfered with the development of the country. The parasite 

 was discovered by Bruce in 1895. Among the natives it is known 

 as tsetse fly disease, and investigation has incriminated Glossina mor- 

 sitans as the carrier. Clinically, the disease in horses is much like the 

 Surra of India ; the native name for the disease, nagana, means weak- 

 ness. Nearly all the larger animals are susceptible to either natural or 

 artificial infection, yet man is apparently immune., 



Morphology. Morphologically, it resembles closely most of the 

 other pathogenic trypanosomes, and Minchin makes it the type of a 

 group of pathogenic trypanosomes, all closely resembling one another 

 and possibly descended from one common ancestor : the group consists 

 of brucei, gambiense, evansi, equiperdum, rhodesiense, and hippicum. 

 The organism is less slender than Icwin and has a wider undulating 

 membrane. The posterior end is relatively short, the trophonucleus 

 lies in the middle of the body and the kinetonucleus at the extreme 

 posterior end ; a vacuole is placed just in front of the latter. In length 

 the parasite measures twenty-five to thirty-five microns and is one and 



