SLEEPING SICKNESS 227 



There is a nucleus (macronucleus) and a blepharoplast (micronucleus 

 centrosome), the latter being located anteriorly as a chromatin staining 

 dot or rod. From this blepharoplast the flagellum proceeds posteriorly 

 bordering the undulating membrane and projecting freely beyond the 

 posterior end. The nucleus is larger, nearer the posterior end, and does 

 not stain so intensely as the blepharoplast. 



Some consider that the trypanosome developed from types with a single anterior 

 flagellum proceeding from a blepharoplast. The moving of the blepharoplast with 

 the flagellum to the other end would make the flagellar end the anterior end. This 

 controversy as to which is the anterior end is the cause of confusion. 



T. gambiense. This is the trypanosome causing human trypano- 

 somiasis, the latter stage of which is known as sleeping sickness. It is 

 from 17 to 2%/J. long, and from 1.5 to 2/* wide. Blepharoplast oval. 



It was first discovered in smears from blood by Ford in 1901, and recognized as 

 a trypanosome by Dutton in 1902, and observed in 1903 by Castellani in the cere- 

 brospinal fluid of patients with sleeping sickness. It is now proposed to consider 

 cases where trypanosomes are not present in the cerebrospinal fluid as in the first 

 stage; when present, as in the second stage. 



It is very difficult to distinguish the human trypanosome from some of the other 

 pathogenic ones by staining methods. The immunity test is the most reliable. 

 An animal recovered from an infection by a certain trypanosome does not possess 

 immunity for other pathogenic ones. Novy and McNeal cultivated T. lewisi in 

 water of condensation on blood agar at room temperature and Thomson and Sinton 

 have recently cultivated both T. gambiense and T. rhodesiense by using rat's blood 

 instead of rabbit's blood in the N.N.N. medium. It is present in the blood, usually 

 in exceedingly small numbers, and in the lymphatic glands of patients. It is by 

 puncture of the glands that we have the best means of finding the parasites. It is 

 also found in the cerebrospinal fluid in sleeping sickness. The parasite stains readily 

 with Wright's stain. The transmitting agent is the Glossina palpalis. 



The life history of T. gambiense is not so well understood as that of certain other 

 organisms. There seem to be certain periods when even with trypanosomes in the 

 peripheral circulation tsetse flies do not become infected. From about 2 to 5% of 

 flies seem to become infective in experiments. When blood containing the so-called 

 short form of trypanosomes is ingested by G. palpalis they reach the gut and remain 

 there unattached. From the fifth to the seventh day they seem to become scarce 

 in the digestive tract but later they reappear in quantity. About the eighth to the 

 eighteenth day long slender forms pass into the proventriculus and later reach the 

 salivary glands as long slender forms. They multiply in the glands and develop into 

 short crithidial forms which later become similar to those found in the peripheral 

 circulation. Robertson considers that the important development takes place in 

 the salivary glands and not in the intestine while Kleine thinks the mature forms 

 the first to appear in the gut. It requires eighteen to twenty days or longer for the 

 complete development and flies so infective remain so for the remainder of life. 



