4t6 



TR YPA NO SOMID^ 



Group 2 : No Part of the Flagellum Free. 



Trypanosoma congolense Broden, 1904. 



Synonyms. — According to Blacklock and Yorke, T. dimorphon [sensu 

 Laveran and Mesnil) ; T. confusum (Montgomery and Kinghorn) ; T. pecorum 

 (Bruce) ; T. nanum (Laveran) , 



This tr5rpanosome causes disease among horses, cattle, sheep, and drome- 

 daries in the French and Belgian Congos and in North-East Rhodesia. It is 

 10 to 17 long and i to 2 broad. Carrier: Glossina movsitans, which is in- 

 fective twenty- three days after a feed thereon. The alimentary canal is full 

 of parasites, and the labrum contains the Leptomonas type, while the small 

 infective trypanosomes are in the hypopharynx. 



Trypanosoma dimorphon Laveran and Mesnil, 1904. 



This trypanosome was discovered by Dutton and Todd in 1904 in horses 

 on the Gambia, and is now known to exist in several parts of Africa, where 

 perhaps a wide equatorial belt across the continent is affected. It is also 

 found in cattle, dogs, pigs, sheep, and goats. 



Morphology. — It exists in three forms: 



I. Tadpole Form. — Found in the early stage of the disease, 11 to 13 long 

 and 0*1 8 ^ broad. 



Fig. 104. — Trypanosoma dimorphon Laveran and Mesnil. 

 (After Dutton and Todd.) 



2. Stumpy Form. — Seen when the disease is not too far advanced, and 

 characterized by a short thick body and a short flagellum. Length 16 to 19 

 breadth 3-4 to 3-5 fjL. 



3. Long Form. — With long thin body and long flagellum, found a few days 

 before death. Length, 26 to 30 breadth, i'6 to 2 ix. 



These may be respectively indifferent, female, and male forms of the para- 

 site, a view supported by Hindle. 



It has been cultivated, and it can be inoculated into rats, mice, guinea-pigs, 

 and rabbits, as well as horses. 



Life-History. — ^Hindle's observations show that the indifferent forms give 

 rise to latent bodies or cysts which gather in the spleen, where they lie dormant 

 for a time, and finally develop again in trypanosomes. It apparently can 

 undergo development in Glossina palpalis, as Bruce and Hamerton have 

 shown that it is a carrier, while Bouet and Roubaud have shown thatG. tachi- 

 noides and G. longipalpis can also transmit the parasite as in G. morsiians. 

 The development is by multiplication in the intestine, and then in the form of 

 Leptomonas or Crithidia in the proboscis, after which the fly becomes infective 

 in about eighteen days frpni the date of the infective feed. 



