Browsing by Author "Fairbairn, H."
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Item The Agricultural Problems Posed by Sleeping Sickness Settlements.(1943) Fairbairn, H.Before the advent of the European the natives of Tanganyika Territory lived in large,compact settlements. These large settlements were formed as defensive communities; they contained, usually, large herds of cattle obtained by raiding or otherwise; and with the clearing of bush which took place to provide the 'people with the necessary agricultural land,they formed a positive measure against trypanosomiasis of man and stock. Following the arrival of European rule and the suppression of inter-tribal warfare, the settlements tended to break up, this tendency being accelerated by the German corVl!e system and the demands for porters in the war of -1918. Families left the larger cleared areas and scattered in the bush, living by -themselves or in groups of only a few families. In these conditions they were unable to keep cattle, but were ,themselves healthy. On the introduction,however, of sleeping sickness into such an area of tsetse infested bush, Iarge-scale epidemics occurred. For a fuller account of this alteration in native life the reader should consult Maclean (1929).Item The Composition of Tsetse-Fly Saliva I.-A Histochemical Analysis(1956) Fairbairn, H.; Williamson, J.; West Africa Institute of Trypanosomiasis ResearchBurtt (1946b) has described a method of inducing tsetse-flies to extrude their saliva onto glass slides, and has published photomicrographs illustrating a number of features shown in the stained saliva. Burtt covered his slides with albumen, but later it was found (Fairbairn and Culwick, 1949) that, if the slides were absolutely grease-free, the saliva adhered properly during fixation and the preparation after staining was much cleaner. This' probe' technique has been used extensively during the last 10 years for the isolation of flies (Glossina palpalis, G. morsitans, G. swynnertoni and G. pallidipes) infected with the polymorphic trypanosomes and with Trypanosollla congolense. Unstained clean (i.e., uninfected) saliva appears as milky-white threads on the slide when it is held up to the light. Unstained saliva from a heavily infected fly, however, is almost invisible, and such slides, when made by untrained technicians, are apt to be thrown away in the belief that the fly has not probed.Item The Differentiation of the Polymorphic Trypanosomes(1949) Fairbairn, H.; Tinde Laboratory TanganyikaThe relationship of the polymorphic trypanosomes, T. gambiense, T. rhodesiense and T. brucei, has been a controversial subject for many years. Owing to the absence of any more definite morphological difference, the discussion has centred round the occurrence of posterior-nuclear forms and such biological characters as infectivity to man, the type of disease produced in man and in small laboratory animals, the susceptibility of the trypanosomes to normal human serum and to arsenical drugs, the red-cell adhesion test, etc. Lester (1933) examined a number of Nigerian strains of T. gambiense and stated that 'The writer believes with Kleine that the two trypanosomes [i.e., T. rhodesiense and T. gambiense] are identical. The trypanosome described as T. rhodesiense is nothing more nor less than a virulent strain of the ordinary human trypanosome T. gambiense. Kinghorn and Yorke (1913), Bruce et al. (1914), Wenyon (1926), Yorke, Adams and Murgatroyd (1930) and Duke (1935) maintained that T. rhodesiense was the same as T. brucei, being merely a strain of the latter which had become established in man, while the German workers (Kleine, Taute, Huber, Beck, quoted by Wenyon, 1926) maintained that they were distinct species. Fairbairn and Burtt (1946) found that a strain of T. rhodesiense, cyclically passaged by Glossina morsitans through sheep for 101 years, had acquired gambiense characteristics; and, while they did not express an opinion on the relationship of T. rhodesiense to T. gambiense, they strongly supported the view that T. rhodesiense and T. brucei were distinct, and not convertible into one another. Van Hoof, Henrard and Peel (1944) considered that they could distinguish T. gambiense from the brucei-rhodesiense group by the distribution, relative number and shape of the trypanosomes developing in the salivary glands of G. palpalis; but such factors are no more exact than the biological characters previously used.Item The Infectivity to Man of Syringe Passaged Strains of Trypanosoma rhodesiense and T. gambiense(Taylor & Francis Online, 1956) Fairbairn, H.; Annals of Tropical Medicine & ParasitologyTHE SYRINGE-PASSAGED STRAIN OF T. RHODESIENSE A strain of Trypanosoma rhodesiense isolated in October, 1934 (Corson, 1936), was still infective to man after being passaged through sheep by cyclically infected•· Glossina morsitans for 18! years (Willett and Fairbairn, 1955). In October, 1936, rats were inoculated from the 13th sheep host. This line was syringe-passaged, and rats of either the 16th or the 18th rat-passage were sent to Dr. CA Hoare, of the Wellcome Laboratories of Tropical Medicine in London. From March 17th, 1937, when they were received in London, until May 6th, 1955, the strain was syringepassaged through 2,306 mice, a period of x8! years by syringe passage from the 13th flyinfected sheep.Item The Local Reaction in Man at the Site of Infection with Trypanosoma Rhodesiense(1957) Fairbairn, H.; Godfrey, D.G.; West Africa Institute of Trypanosomiasis ResearchA problem of great importance in trypanosomiasis is what happens to the metacyclic trypanosomes when they are injected into a mammal by the bite of an infected tsetse-fly. Gordon and Willett (1956) infected guinea-pigs by the bites of tsetse-flies cyclically infected with Trypanosoma rhodesiense. By the subinoculation of heart blood into rats they showed that the blood of the guinea-pigs was infective 5 minutes, 45 minutes, 4! hours and 24 hours after the infective bite. In a fresh preparation made from the site of the bite within five minutes of its infliction, a single trypanosome was seen; and ground-up tissue, removed from the bitten area within 45 minutes of the infective feed, successfully infected white rats on two occasions. The only occasion on which they found trypanosomes on sectioning the site of bite was immediately after a fly had probed but not fed. They postulated that in guinea-pigs the majority of the metacyclic forms of T. rhodesiense deposited by the feeding tsetse rapidly migrated or were carried away from the site of the bite; that a proportion of these trypanosomes or their descendants reached the general circulation within a few hours, or sometimes within a few minutes, of the infective bite; and that, once the trypanosomes reached the circulation, they persisted in the blood throughout the incubation-period. Their guinea-pigs, however, still had an incubation-period of 7-10 days before trypanosomes were found microscopically in the blood.Item Measurements of Strains of Trypanosoma Congolense(1962) Fairbairn, H.; University of Cape TownThe question whether Trypanosoma dimorphon is a species distinct from T. congolense has been reopened by Hoare (I959)· He examined, and measured the trypanosomes in, the original slides of Laveran and Mesnil which were the type material for establishing T. dimorphon as a distinct species. He found that the length of the trypanosomes ranged from II to 24, u, and that the mean lengths varied from I 5· 3 to I7· 6, u.(These measurements were made in slides from four mice, four rats and two goats.) In the strains of T. congolense recorded by Hoare, the length of the trypanosomes ranged from 8 to I9· 5, u and the mean lengths varied from I2" 3 to If· f, u. He states that'The means of each of these species form a continuous group, without a real break in the variation of length between the respective strains and/or samples, but there is a definite gap between the highest mean of the shorter species (I4· 4, u) and the lowest mean of the longer one (I5· 3, u).'He concluded that'As the result of the present revision, the differential diagnosis of T. dimorphon is so well defined that it should now be removed from the synonymy of T. congolense and restored to its original status as an independent species.'He admitted, however, that the occurrence of strains with intermediate mensural characters could not be excluded, and that if their existence were confirmed it might be necessary to reduce the rank of T. dimorphon and other congolense-like strains to some minor taxon.Item The Penetration of Trypanosoma Rhodesiense Through the Peritrophic Membrane of Glossina Palpalis(Taylor & Francis, 1958) Fairbairn, H.; West Africa Institute of Trypanosomiasis ResearchWhen Trypanosoma congolense, T. gambiense or T. brucei infect the tsetse-fly, the first stage of development occurs in the mid-gut, where the trypanosomes are attached to the cell wall in the ectoperitrophic space (Johnson and Lloyd, I929; Taylor, I932; Yorke, Murgatroyd and Hawking, I933)· The trypanosomes multiply in the mid-gut, outside the peritrophic membrane, and extend anteriorly until they reach the region of the proventriculus. In order to continue their further development in the labrum or salivary glands, the proventricular forms have to pass through the membrane. Yorke et al.(I933) showed that T. brucei was present in the space between the annular pad of secretory epithelial cells and the invaginated portion of the fore-gut, and that in that region the parasites passed through the peritrophic membrane where it was being secreted and where, presumably, it was still fluid. A tsetse-fly, Glossina palpalis, infected with T. rhodesiense, was fixed in Bouin's alcoholpicro-formol with one drop of chloroform added to each millimetre of fixative (Hoare, I93I), and was embedded by the celloidin-paraffin wax method. Serial sections were cut at 81t thickness and stained by the Giemsa-colophonium method of Shortt and Cooper (I948).Item Some Problems of Human Trypanosomiasis In Africa(1958) Fairbairn, H.Van Hoof (1947) found that strains of T. gambiense in the Belgian Congo could be divided into three types, according to their virulence and their pathogenicity to man.Item Studies on Trypanosoma Vivax Ix.-Morphological Differences in Strains and their Relation to Pathogenicity(1953) Fairbairn, H.; West Africa Institute of Trypanosomiasis ResearchIn East Africa Trypanosoma vivax infections of cattle are usually considered to cause a mild disease. Hornby (1921) stated that in his experience, although T. vivax was pathogenic for cattle, it was less so than T. congolense. Carmichael (1948) expressed the opinion that T. vivax did not cause severe disease in animals kept in good condition, and Fiennes (1950) stated that T. vivax usually caused a chronic or benign type of disease, which in a high proportion of cases ended in recovery. Hornby (1952) wrote that' T. vivax has the reputation of being, on the whole, of low pathogenicity,' and his experiments testified to the usual mildness of T. vivax infection. Cornell (1936), on the other hand, reported acute fatal cases in the Mbulu district of Tanganyika Territory; Hudson (1944) recovered three strains of T. vivax from Emali, Solai and Machakos in Kenya, which caused an acute disease in cattle, with trypanosomes 'swarming' in the blood; and Lewis (1948) recovered an 'extremely virulent' strain from Emali, and reported the occurrence of similar strains from other parts of the Central, Rift Valley and Coast Provinces of Kenya. Nevertheless, in East Africa T. congolense is generally considered the most important animal trypanosome (Hornby, 1952).Item The Transmission of Trypanosoma Vivax by Glossina Palpalis(1955) Fairbairn, H.; Watson, H.J.C.; West Africa Institute of Trypanosomiasis ResearchZiemann (1912) pointed out that the infection of domestic animals with Trypanosoma vivax in the Cameroons seemed, like malaria, to show a definite curve. There was an increase of new infections both at the height of the rainy season and at its end, corresponding, he considered, to the increase in the number of tsetse-flies. Lloyd and Johnson (1924) found a seasonal variation in the proportion of Glossina tachinoides infected with T. vivax, the mature infections increasing as the rains progressed; they attributed this variation to the increasing average age of the flies, since few young flies were emerging during the rains. Squire (1951) found a marked seasonal fluctuation in the infection rates of G. palpalis with T. vivax, the incidence being highest during the months of heavy rainfall (July-October). He divided his flies into age-groups, according to the wing colour and fraying, and, as the results were based on his age-groups 2 and 3, there was no question of the infection rates being upset by the presence of newly emerged flies, which had not yet had a chance of becoming infected. He thought that there might be a positive correlation between infection rates and rainfall and a negative correlation with sunshine. Nash and Page (1953) also found a seasonal variation in the infection rates of G. palpalis with T. vivax, the peak again being highest in the rainy season; they too considered that this wet-season peak was associated with the increase in average age of the flies during the rains.
