233 



TRYPANOSOMIASIS IN THE ABSENCE OF TSETSES, AND A HUMAN 

 DISEASE POSSIBLY CARRIED BY SIMULIUM IN KENYA COLONY. 



By F. W. Dry, M.Sc, 



Recently Assistant Government Entomologist, Kenya Colony. 



(Plates VII & VIII). 



This is an account of two different inquiries carried out on the same safari in the 

 Lumbwa country of Kenya Colony early in 1920. The problems are of the same type, 

 the suspected transmission of disease by blood-sucking flies, and the second investiga- 

 tion arose out of the first. It therefore seems best to deal with them both in a single 

 paper. 



In March 1920, in the absence of my Chief, Mr. T. J. Anderson, I was asked to make 

 a fly survey in the neighbourhood of "a farm in the Kericho district where cases of 

 trypanosomiasis had been demonstrated. I arrived at this farm on 25th March. The 

 blood-sucking flies collected are listed below. As was anticipated, the altitude being 

 about 6,300 ft., and there being no records of tsetse-fly anywhere near, none 

 was found. I was then fortunate in receiving information from Mr. Ian Q. 

 Orchardson, the pioneer settler of the Kericho district, about a small blood-sucking 

 fly to be found in the forest in part of the Lumbwa Reserve. The bites of this fly, 

 he told me, are believed by the Lumbwa to be the cause of a disease from which some 

 of the inhabitants of that region suffer. He further suspected that this fly might 

 transmit a disease of cattle. Accordingly, on 7th April, I proceeded into the area 

 about which he had told me in the Lumbwa Reserve, also crossing the Kipsoni into 

 adjacent country of the Kisii Reserve. The fly proved to be a Sinmlium. I satisfied 

 myself that it could not be regarded as the transmitting agent of any cattle disease, 

 but did obtain evidence which shows that the belief of the Lumbwa calls for further 

 investigation. On 29th April, I returned to the farm near Kericho, to search for 

 Simulmm there, but failed to find it, staying there until 3rd May. 



I. Possible Transmission of Trypanosomiasis in the Absence of Tsetses. 



The presence of trypanosomiasis on the farm near Kericho was demonstrated 

 from blood-shdes taken by the late Captain J. Cameron, Veterinary Officer, and 

 examined by Mr. W. Kearney, Assistant Veterinary Pathologist. His diagnosis 

 of the tvpe of trypanosome was confirmed by Mr. R. E. Montgomery, now Veterinary 

 Advisor in Uganda, who wrote to Mr. Kearney in January 1920 :— " On purely mor- 

 phological features, the trypanosomes are recognisable as Tr. tmiforme. 



The bold body, slightly developed, undulating membrane, short, free flagellum, dis- 

 tinct blepharoplast and clear cytoplasm all point to this species, or a near relative 

 of the vivax group." 



The farm where the outbreak occurred was a new one, and all the cattle on the 

 farm, other than those of native squatters, were working oxen which had been bought 

 and brought on to the farm towards the end of 1919 or early in 1920. 



In 1919 there had been no deaths of oxen, apart from one animal which died 

 after an accident, but from early January up to my arrival there had been a high 

 mortality, and trypanosomiasis had been demonstrated from blood slides in some 

 cases. Particulars about the losses up to the time of my visit are as follows : — 

 Total number of European owned oxen . . . . . . 63 



Deaths : — 



Trypanosomiasis proved by blood-slides . . . . 2 



Not due to any disease . . . . . . . . • • 2 



Cause not proved . . . . . . • . . • • • 14 



