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NATURAL TRANSMISSION OF TRYPANOSOMIASIS (T. PECORIM 

 GROUP) IN THE ABSENCE OF TSETSE-FLY. 



By Rupert W. Jack, F.E.S., 



Government Entomologist, Southern Rhodesia. 



(Maps I & II.) 



The opinion that trypanosomiasis of the T. pecorum type is, under favourable 

 conditions, transmissible amongst domestic stock through the agency of blood- 

 sucking flies other than Glossina has been expressed by several observers.* 



Observations in Southern Rhodesia during the past seven years have convinced 

 the writer that, given the necessary conditions, transmission of this disease may 

 take place in the absence of tsetse-fly, and that such transmission has occurred more 

 frequently than has been generally recognised. It may be of interest therefore to 

 give the facts concerning several outbreaks in the territory which form a chain of 

 evidence pointing to the above conclusion. The trypanosome was in each case 

 diagnosed by Mr. LI. E. W. Bevan, Veterinary Bacteriologist, S. Rhodesia : — 



I. T.'s cattle. Farm on railway about 3 miles N.E. of Gatooma. Season 1909-10. 

 Ten cattle were brought to farm about 26th October 1909, from Victoria, but had 

 been by rail to Salisbury and back to Gatooma. Two were brought to farm about 

 6th December. At the time of my visit, 31st January, the two latter were healthy ; 

 but the remainder, of which one had already died, were all " fly-struck," the first 

 case having been noticed during the first week in January. The range of the cattle 

 was confined to the farm, the road between the farm and Gatooma and across the 

 railway to the Cam mine. Fly is known to exist 3 to 5 miles to N.E. (see Map I). 

 The writer spent a full week looking for fly on this farm and in the vicinity with 

 negative results. A few specimens of Tabanus and a few Stomoxys calcitrans were 

 seen about the cattle. Early in March the two remaining cattle fell sick and were 

 diagnosed by Bevan as suffering from trypanosomiasis. Since that year cattle 

 have lived in a healthy state on this farm. 



II. H.'s cattle. Farm within 2 miles of Gatooma to S.E. Season 1909-10. 

 Forty cows were on the farm for sixteen months and out of these nineteen showed 



symptoms of trypanosomiasis (diagnosed by Bevan). The only occasion on which 

 any left the farm was from August to November, 1909, when all but six went to 

 the Inez Mine (opposite direction to the fly belt). The first case was recorded in July 

 1909. Stomoxys calcitrans, Lyperosia sp. and two species of day-feeding mosquitos 

 were common about the range of the cattle. No tsetse was seen on or near this farm, 



* (1). Kinghorn & Montgomery: "A Keport on Trypanosomiasis of Domestic 

 Stock in N.W. Khodesia." — Ann. Trop. Med. Parasit., June, 1908. 



(2). G. E. Owen : " Mechanical Transmission in Trypanosomiasis." — Jl. Comp. Path. 

 Therap., September, 1914. (The species of Trypanosome in this instance is not certain.) 



(3). H. Llewelyn Jones : " The Treatment of Trypanosomiasis in Cattle caused by 

 the Trypanosoma pecorum." — Jl. Comp. Path. Therap., June, 1915. 



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