TRYPANOSOMA GAMBIENSE 525 



somiasis, and that the trypanosomes of Button and Castellani were 

 identical. Hence, T. gcunbiense stands as the correct name, while the 

 other names become synonyms. 



Distribution. — T. gambiense occurs only in Africa. On the West 

 Coast it is limited to a district between 15° N. and 15° S. of the ec^uator. 

 Further east, it is restricted to the area between 10° N. and 10° S., its 

 eastern limits being Lakes Victoria and Tanganyika. In these regions 

 it occurs in greatest intensity along the rivers and shores of the great 

 lakes, and, wherever it is found, there the tsetse fly, Glossina palpalis^ 

 also occurs. This association of the fly with the infection in man led to it 

 being suspected as the carrier of the disease, but the actual part played 

 by the fly was never properly explained till Kleine made his observations 

 on the behaviour of trypanosomes in tsetse flies, the first account of which 

 was published in 1909. 



Symptomatology. — In the blood of man the trypanosome never occurs 

 in great numbers, and long search may be required to discover it. Some- 

 times it can be more readily found by examination of fluid obtained by 

 puncture of an enlarged lymphatic gland, and later in the disease in the 

 cerebro-spinal fluid. At other times its presence has only been demon- 

 strated by inoculation of fairly large quantities of blood (20 c.c. or more) 

 into some susceptible animal like the monkey. As a rule, however, careful 

 search of one or more ordinary blood-films will reveal its presence. 



This may have to be repeated on several occasions, for, as is usual in 

 these infections, the number of trypanosomes in the blood is subject to 

 definite fluctuations. Age and sex do not appear to influence infection to 

 any extent unless, owing to habits of occupation, any particular age or sex 

 is more liable to exposure than another. 



It has been noted in certain districts of Africa that natives may be 

 found to harbour the trypanosome, though apparently perfectly healthy. 

 On this account it may be difficult to give a definite incubation period, 

 which is said to vary between two or three weeks and seven years. 

 Generally, the first symptom noted is irregular fever, which is uncontrolled 

 by quinine. This is followed by enlargement of the lymphatic glands 

 and spleen, anaemia, and wasting. A cutaneous eruption in the form of 

 circular red patches may occur. This stage is due to the invasion of the 

 blood and lymphatic system by the trypanosomes. A second stage is 

 due to the extension of the infection to the central nervous system, during 

 which various nervous symptoms become manifest, leading finally to that 

 lethargic condition which has given rise to the name sleeping sickness. 

 Recovery frequently takes place as a result of treatment in the first stage 

 of the disease, but more rarely when the second stage is reached (see p. 459). 



