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A dissertation submitted to the faculty of Science, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Master of Science. Johannesburg, 2014. / Human African Trypanosomiasis (HAT) is transmitted by Glossina species and remains a serious health problem in Africa. Many aspects of control of the disease have been implemented throughout the years but vector control of tsetse flies has proven to be the most efficient long-term solution. Vector control interventions have been implemented for many tsetse species but relatively little is known about the behaviour of the riverine species, Glossina fuscipes fuscipes. Increased knowledge of this species would improve vector control interventions. This study aimed at: i) understanding the behaviour of tsetse flies around visual devices and odour baits; ii) understanding the behaviour of the flies with regard to human activities; iii) understanding the interaction between the nutritional status of tsetse flies and their attraction to various trapping devices (biconical traps and electric nets); and iv) establishing an age determination curve for field-caught flies. Results showed that visual targets were better attractants then odour-based ones and electric nets performed better than biconical traps. The sticky traps caught 10x more flies (males) than the stationary biconical traps. Sticky traps caught more young flies than the biconical traps which caught more old flies. An age curve was established for flies ranging from 1 day to 60 days old and the fluorescence-based age determination technique, using pteridine levels, has been shown to work for this species. Understanding the behaviour of tsetse flies around trapping devices should lead to improved trapping efficiency. The data gathered will be of importance in assisting with designing and running the Lake Victoria region control operations planned by PATTEC and it will have application in G. f. fuscipes endemic regions in other parts of Africa.

No description available.

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The surface molecules (procyclins) of procyclic forms of African trypanosomes (Trypanosoma brucei spp.) are complex mixtures of lipid-anchored glycoconjugates. The procyclins are expressed differentially during the parasite life cycle within the tsetse fly vector. It has been hypothesised that these surface molecules are involved in interactions with molecules of the tsetse fly and may influence differentiation, cell death and tissue tropism. To understand procyclin functions it is necessary to identify and characterise them. This thesis presents a study of the biochemical and immunochemical characteristics of the major surface molecules of Trypanosoma simiae and Trypanosoma congolense, animal pathogens of the subgenus Nannomonas that share the same developmental cycle and tropism within the tsetse vector. Organic solvent extraction, reverse-phase high performance liquid chromatography and enzyme-linked imnunosorbent assay using surface binding monoclonal antibodies were used to isolate membrane molecules of procyclic culture forms (PCF) of both trypanosome species. Gel electrophoresis of the purified molecules revealed two predominant molecular species from each parasite that were broadly similar yet showed different apparent molecular masses and staining characteristics. The molecules were shown to be glycosylphosphatidylinositol-lipid anchored glycoconjugates, comprised mainly of carbohydrates. Each moiety displayed surface-disposed carbohydrate epitopes that were recognised on the surface of both species of trypanosomes by monoclonal antibodies specific for procyclic parasites of the subgenus Nannomonas. The epitopes were previously shown to be displayed on the glutamic acid-alanine rich protein (GARP) of T. congolense, yet neither this protein (as detected either immunologically or by mass spectrometry) nor its encoding gene (as detected by Southern blot analysis) was present in T. simiae. The results indicate that although T. congolense and T. simiae share common carbohydrate surface epitopes, these are displayed on biochemically different molecules. I hypothesise that the surface disposed carbohydrate structures and not the polypeptide moieties are involved in parasite-tsetse interactions since these species have the same developmental cycles in the insect vector. In an attempt to obtain primary sequence information for the T. simiae PCF surface molecules, I identified and characterised an unique open reading frame. This was shown to be expressed as a protein in PCF and is likely a membrane-associated molecule of the subgenus Nannomonas. / Graduate

The problem of controlling tsetse flies in Africa is an old one. The tsetse fly transmits the trypanosome parasites which cause sleeping sickness in humans and disease in cattle. Because cattle are a favoured food source for tsetse much work has been done looking at the use of insecticide treated cattle as a control strategy for the tsetse fly. Such treatment methods possess many advantages; they are safe and relatively environmentally benign, they can be applied by individual farmers without the need for logistically demanding and costly traditional control programmes and, in addition to tsetse flies the insecticides are effective against a wide range of other harmful cattle parasites. The cost of the insecticide is however a significant constraint to the number of livestock keepers who can afford to employ the technique and as a result many cattle remain untreated. Following the discovery that tsetse had a significant predilection for feeding on the legs and belly of cattle, it was hypothesised that restricting the insecticide to only those areas could offer comparable protection to treating the whole animal. Such an approach would use up to 80% less drug and thus make the treatment per animal much cheaper. In addition, preferentially targeting areas favoured by tsetse, and leaving the rest of the animal untreated, preserves some important ecological balances between cattle and their parasites which traditional treatment methods destabilise. This thesis describes the design, implementation and analysis of a longitudinal study run over 8 months in south east Uganda that sought to compare the effect of applying insecticide to cattle only on the regions favoured by tsetse flies. Cattle were recruited to the study and assigned one of four treatment groups; a whole body application of deltamethrin insecticide pour-on; a restricted application of deltamethrin spray, applied to the front legs, ears and belly; a prophylactic trypanocide injection of isometamidium chloride, and a control group, that received no further treatments. All animals in the study were however cleared using twin doses of a trypanocide diminazene aceturate at the start of the study.

A brief account of the history of government organised tsetse and trypanosomiasis control in Nigeria is presented, and major features of the tsetse eradication programme are summarised. The achievements are considered in the context of widespread environmental change, brought about by an increasing human population, and a long term process of agricultural expansion, which have resulted in an overall reduction in natural tsetse habitats and hosts, and led to a general decline in tsetse populations. A comparison of two areas, one within, and the other outside the tsetse eradication zone, showed that they had both experienced similar rates of change in land use, and available information indicated that human and cattle populations had also increased at similar rates. The present day distribution and abundance of tsetse and cattle in a region of the Nigerian sub-humid zone, not yet reached by the tsetse eradication programme, are described. In the virtual absence of wildlife, abundance of cattle, and concentration of the two riverine tsetse species at crossing points, it was concluded that tsetse were largely dependent on cattle and/or man for their survival. The low density of riverine tsetse populations, their restricted distribution and their low infection rates, combined with Fulani herd management practices, which limited the period of contact between tsetse and cattle, indicated that under the prevailing conditions, trypanosome challenge was likely to be very low. It is suggested that this situation was typical for many areas within the sub-humid zone, and that in the future, similar conditions are likely to become even more widespread. It is concluded that, whilst government trypanosomiasis control programmes must have contributed to the general decline of the disease which has taken place, the environmental context within which they were mounted, has changed significantly. Over the past fifty years human population has almost certainly increased three or four fold, and the extent and intensity of both farming and hunting have increased commensurately. This has resulted in an overall reduction in natural tsetse habitats and hosts, which has led to a decline in vector populations. It is argued that this, together with a trend for Fulani and their cattle to become more sedentarised, has brought about a fundamental change in the balance of relationships in the vector-host-disease complex, which has favoured the development of appropriate immune responses in Fulani cattle, and the selection of less pathogenic strains of trypanosome.