Browsing by Author "Willett, K.C."
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Item Studies on the Deposition, Migration, and Development to the Blood Forms of Trypanosomes Belonging to the Trypanosoma Brucei Group: III.—The Development of Trypanosoma Rhodesiense from the Metacyclic Forms, as Observed in Mammalian Tissue and in Culture.(1956) Gordon, R.M.; Willett, K.C.; Liverpool School of Tropical Medicine; East African Trypanosomiasis Research Organisation, Uganda.In a previous paper (Gordon and Willett, 1956) we gave a preliminary account of the deposition, migration and development of the metacyclic forms of Trypanosoma rhodesiense as observed in the mammalian host. This was followed by a paper (Gordon, Crewe and Willett, 1956) in which we described in some detail the methods by which the tsetse-fly obtained its blood-meal and the relation of this method of feeding to the deposition of saliva, and therefore of any contained metacyclic trypanosomes, into the tissues and the blood-stream. In a later paper (Willett and Gordon, 1957) it was shown that in the guineapigs and rats examined by us there was no chancre formation or obvious multiplication of trypanosomes at the site of inoculation, either of blood forms injected by syringe or of metacyclics injected by the feeding tsetse, but that in both instances there was an almost immediate invasion of the circulation by trypanosomes, which persisted throughout the incubation-period. It was shown also that in the rabbit* a similar immediate invasion of the blood-stream and a similar persistence of trypanosomes in the circulation occurred, and that, in addition, some of the injected trypanosomes remained and multiplied at the site of inoculation, giving rise to a typical chancre very closely resembling that which has been observed in the human host. As a result of these and of other observations we concluded that the process of migration and development of trypanosomes of the T. brucei group in the rodent host during the incubation-period is fundamentally the same whether the inoculum be of metacyclic forms or blood forms, and whether it be into an animal which shows a local reaction, such as the rabbit, or one that does not, such as the rat or guinea pig.Item "Zoonoses in East Africa" May 1956(1956) Willett, K.C.; East African Trypanosomiasis ResearchIN the report of the recent conference in Kampala, Uganda, "Zoonoses in East Africa"" I was quoted as suggesting that Trypanosoma rhodesiense had (developed from Tr. brucei by repeated passages through Glossina pallidipes. My thesis was, in fact, almost the exact opposite of this. I emphasized that all the evidence so far shows that the property of infectivity to man which alone distinguishes Tr. rhodesiense from Tr. brucei is an extremely stable one and that there has never been a known case of interconversion of these two. On the other hand, I pointed out, in any area where Tr. rhodesiense had appeared, either it could be traced to direct introduction by infected human beings from a known source, or the other human infective 'species', Tr. gambiense, had been known to be present in the area for some time.
