XIV] EL DEBAB 235 



Captain Hadow sent to the Wellcome Research Laboratories 

 blood smears from two sick bulls at Kadugli, Kordofan. These 

 were examined by Dr Balfour and found to contain numerous 

 trypanosomes, the species probably being T. hrucei [or pecaudi) . 

 These bulls could not have been bitten by tsetse-flies, for the 

 only tsetse area in Kordofan is at Kawalib, sixty miles from 

 Kadugli. The infection was attributed by the Arabs to the 

 serut fly [Tabanus or Pangonia). 



The circumstantial evidence in support of the view that 

 El Debab, a disease affecting dromedaries in the North of Africa, 

 is mainly carried by Tabanids, is much stronger than in the 

 case of the other African trypanosomiases. The natives of 

 North Africa from time immemorial have accused the serut 

 flies of inoculating this disease into the dromedaries. When 

 these animals remain during the summer in regions where 

 Tabanids are numerous, the mortality from El Debab in the 

 following months is very great. On the other hand, if Tabanids 

 are few or absent, the disease seems to be unable to become 

 established. 



In Algeria the majority of the Tabanids appear between 

 the ist and 15th of June ; they last for about forty days and 

 then disappear, as soon as their enemies the Asilids begin to 

 hatch out. The Tabanids live in the damp valleys and often 

 frequent the tufts of Thapsia, appearing as soon as this plant 

 flowers, and disappearing after it has withered. 



Experimentally, Drs Edmond and Etienne Sergent, in 

 Algeria, have been able to transmit T. soudanense, the patho- 

 genic agent of El Debab, by the bites of Tabanus nemoralis, 

 Mg. and T. tomentosus Macq. 



The flies were first allowed to bite heavily infected rats or 

 mice and subsequently fed on healthy animals. When there 

 was no interval between the two feeds, five successful trans- 

 missions were obtained, and in one case after an interval of 

 22 hours the flies were still infective. Throughout these 

 experiments only rats and mice were employed, never the 

 natural host of the trypanosome. 



These results are in harmony with what is known about the 

 history of the disease. 



