Thesis (MSc)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Age and temperature are two factors that affect mortality in adult tsetse flies. Both are found to be very important, but the simultaneous effect of these factors on the mortality rate have not been studied. This study seeks to address this, with an application to a population of female tsetse, using a model based on partial differential equations. Adult mortality is agedependent and is modelled as the sum of two exponentials, with four parameters (coefficients of each exponential): numerical analysis of a population model with this mortality structure predicts exponential growth. Analysis of each of the parameters through parameter variation shows that two of these parameters control the mortality of the nulliparous (ages 0 − 10 days) flies only while the other two only take care of flies of mature ages. Measurement of the impact of these parameters on the mortality of tsetse of different ages by the normalized forward sensitivity index method is also carried out. This is followed by fitting the model based on the age-dependent mortality along with a constant tsetse birth rate to data representing the catches of female Glossina pallidipes at Rekomitjie Research station, Zimbabwe. Considering a three parameter adult tsetse mortality, parameter analysis shows the effect of one of the parameters to affect the mortality of flies of all ages while a second controls only the mature tsetse flies of reproductive ages. A further analysis resulted in the estimate of these parameters as functions of temperature, thereby leading to the establishment of an age and temperature-dependent adult tsetse mortality. Using data for the daily average temperature records obtained in 1981 on Antelope Island, Lake Kariba, Zimbabwe, daily changes in the pupal duration (adult tsetse birth rate) changes negatively with temperature change. Incorporating this (temperature-dependent ) birth rate into the model, together with the established age and temperature-dependent adult mortality, the adult tsetse population dynamics is explored numerically. The latter model is then fitted to population data of female Glossina morsitans morsitans obtained from the same Island and for the same period as used for the temperature data. The data suggests peak tsetse population to be in the month of July and lowest in the month of December. The first quarter of the year is predicted to be most favorable for breeding tsetse while the second, showed a period of stable growth rate and a time of tsetse abundance. In addition, the dynamics with both age and temperature showed a non-uniform daily population growth contrary to that with age effect only. This study has enhanced our understanding of tsetse population dynamics for age and temperature-dependent adult mortality with temperature-dependent pupal duration and suggests the period of tsetse abundance on Antelope Island. / AFRIKAANSE OPSOMMING: Geen opsomming in Afrikaans.

In October 2006 an intervention was initiated to arrest the northerly advance through Uganda of the zoonotic parasite Trypanosoma brucei rhodesiense. This is a protozoal infection that is vectored by the tsetse fly. It is the aim of this thesis to review the impact of this large scale treatment programme in terms of animal health and human disease. The Stamp Out Sleeping Sickness (SOS) campaign was designed to target the cattle reservoir of T. b. rhodesiense in these newly affected areas by block treating >180,000 head of cattle. This was achieved in collaboration with final year vet students from the University of Makerere, Uganda. Farmers were also encouraged to spray their animals with deltamethrin in order to suppress the tsetse population. In order to monitor the impact of this intervention a base line survey was carried out. Evaluation of the logistics and implementation of the SOS campaign was assessed through interviews with personnel involved. Analysis by PCR revealed the prevalence of T. brucei s.l. as 15.57% (T. b. rhodesiense as 0.81%) within the cattle reservoir prior to SOS treatment. Follow up sampling was carried out at 23 locations at three, nine and 18 months. The prevalence of T. brucei s.l. was reduced post treatment, but in the absence of sustained vector control infections amongst the animals returned by nine months and subsequently exceeded the base line findings (P=<0.0001). It was observed that across most of the SOS area, T. b. rhodesiense did not re-establish following treatment. However, a significant cluster was identified where cases of both human and animal disease were continually reported. This cluster was noted to include the area immediately surrounding the Otuboi cattle market. This link between cattle movement and the spread of T. b. rhodesiense is an established one and is addressed by Ugandan governmental policy which states that ‘cattle traded at market must be treated with trypanocidal drugs prior to movement’. The findings presented here suggest that this policy may not be strictly enforced. The risk of spread is compounded at the northern districts of Uganda restock their domestic livestock following years of civil conflict. The majority of animals are traded in a northward direction – transporting infected animals from the endemic south. The scale of this trade is assessed through questionnaires, analysis of trade records and animal screening. Specific consideration is given to the implications of this cattle trade and impact this may have on the sustainability of the SOS campaign.

Trypanosoma brucei is a protozoan parasite that is the causative agent of sleeping sickness in sub-Saharan Africa. T. brucei has a complex life cycle involving passage between a mammalian host and the tsetse fly. The parasite evades the mammalian immune system via expression of Variant Surface Glycoprotein (VSG) on the cell surface. VSG genes are expressed at telomeric expression sites and at these sites are a number of Expression Site Associated Genes (ESAGs). One unusual ESAG, ESAG9, is developmentally regulated: RNA for these genes accumulates during the transition from slender to stumpy cells in the mammalian bloodstream and cellassociated protein is only detected transiently in stumpy and differentiating cells. Transgenic cell lines were generated which ectopically express one or more members of the ESAG9 gene family. Biochemical and cytological analyses using these cell lines indicated that some members of this family are glycosylated and GPI-anchored, and also that one gene, ESAG9-K69, is secreted. ESAG9-K69 is also secreted by wild-type stumpy parasites. In vivo experiments with tsetse flies did not conclusively show whether ESAG9 proteins play a role in the establishment of a tsetse fly mid-gut infection by transgenic trypanosomes. However, In vivo and ex vivo experiments using the mouse model of trypanosomiasis indicated that expression of ESAG9 proteins may alter parasitaemia in the mouse and results in a significant decrease in the proportion of CD4+ T cells in the mouse spleen.

African trypanosomes are protozoan parasites that cause African trypanosomiasis, diseases that affect humans and their livestock. Not only has trypanosomiasis had an overwhelming effect on the development of tropical Africa in the past, but it also constitutes one of the most significant present economic problems of the continent. Trypanosomes alternate between a mammalian host and a tsetse vector using a complex life cycle. In the mammalian host the trypanosomes live as bloodstream forms (BSFs) that are so proficient at antigenic variation, and thus host immune system evasion, that no suitable vaccine candidates have yet been identified. In contrast, the lifecycle stages that exist in the tsetse vector do not undergo antigenic variation. This potentially makes the vector-occupying trypanosomes much better targets for control if strategies can be devised to disrupt their lifecycle in the vector or to interfere with their transmission to mammalian hosts. The primary impediment to developing strategies for disruption of trypanosome life cycles in tsetse is a lack of understanding of the molecular basis of trypanosome-tsetse interactions. Although several major surface molecules have been identified on insect form trypanosomes, these have not been well studied due to a lack of appropriate antibody probes and to the difficulty in obtaining sufficient quantities of the different parasite life cycle stages required for such molecular studies. My thesis research was focused on developing and using monoclonal antibody probes for analysis of expression of major surface molecules of Trypanosoma congolense, a serious pathogen of cattle in Africa. I used this species of trypanosome since in addition to being a socioeconomically important parasite, all four of its major life cycle stages can be grown in vitro in amounts sufficient for immunochemical analysis. I successfully derived and characterized monoclonal antibodies that were useful for detecting the three major surface proteins of T. congolense insect forms: glutamic acid/alanine rich protein (GARP), the T. congolense heptapeptide repeat protein (TcHRP) and congolense epimastogote specific protein (CESP). Selected monoclonal antibody probes were then employed for expression analysis of these molecules throughout the parasite life cycle using in vitro grown trypanosomes and parasites taken directly from infected tsetse. In addition, I determined the peptide epitopes for two of my GARP-specific monoclonal antibodies and in collaboration with Dr. Martin Boulanger and Jeremy Mason was able to localize the epitopes on a high resolution three-dimensional structure obtained by X-ray crystallography. This allowed us to derive a model that describes the orientation of GARP in the trypanosome surface membrane and explains the possible structure-function relationships involved in replacement of the bloodstream form variant surface glycoprotein (VSG) by GARP as trypanosomes differentiate in the tsetse vector after a bloodmeal.

One of the greatest problems for sub-Saharan Africa is shortage of epidemiological data to support planning for provision of adequate public and animal health services. The overriding challenge is to provide the necessary resources to facilitate the process of regular data collection in support of disease surveillance and vector monitoring across target regions. Due to such circumstances, there is currently an increasing interest towards devising cheaper but yet significantly reliable means for availing the needed epidemiological and vector data for planning purpose. This study comes as a contribution towards solving such challenges. The study has three research components starting with a review of past Uganda national tsetse and trypanosomiasis control efforts as a means towards appreciating the dynamics of controlling the vector and disease. This is an analysis of what was applied, what worked, what didn't, and why it didn’t as linked to the broader vector and disease control system. Secondly through the use of remote sensing, geographical information systems and global positioning technologies tsetse species were sampled within Lake Victoria Basin. Only two species of tsetse were trapped, G. f. fG. f. fuscipes which was widely distributed across the surveyed area, and G. Pallidipes which was detected in a few isolated locations close to the border with Kenya in Eastern Uganda. The analysis of land cover with tsetse findings showed an important association between G. f. fuscipes and particular vegetation mosaics. Unfortunately, while the results are highly informative, approaches for data collection such as this one are costly and unlikely to be sustained by the already over-burdened health systems in the low developed countries of Africa. The third and main part of this study investigates, demonstrates and delivers the possibilities of applying spatial epidemiological modelling techniques to produce both tsetse distribution and abundance maps. Four spatial and non-spatial regression models (Logistic, Autologistic, Negative binomial and Auto-negative binomial), were constructed and used to predict tsetse fly presence and tsetse fly abundance for the study area. The product is an improved understanding of association between environmental variables and tsetse fly distribution/abundance and maps providing continuous representations of the probability of tsetse occurrence and predicted tsetse abundance across the study area. The results indicate that tsetse presence and abundance are influenced differently. Tsetse abundance is highly determined by river systems while tsetse presence is majorly influenced by forested landscapes. Therefore, efforts to control trypanosomiasis through vector control in the Lake Victoria basin will call for delineation of such clearly identified high tsetse accumulation zones for targeted tsetse control operations. This will ensure optimum utilization of the scarce resources and above all contribute to the protection of humans and animals against trypanosomiasis infection.

Please read the abstract in the section 00front of this document / Thesis (PhD (Entomology))--University of Pretoria, 2005. / Zoology and Entomology / unrestricted

The objective of this study was to use molecular biological reagents (primers targeting different genomic loci) and methods (PCR and RFLP) to detect and characterize trypanosomes in cattle, wild animals and tsetse flies in KwaZulu-Natal, thus contributing to improved understanding of the genetic diversity of trypanosome species infecting cattle at the game/livestock interface in the KwaZulu-Natal Province of South Africa. Primers based on sequences of different loci in the trypanosome genome were used in conducting polymerase chain reactions (PCRs) on samples collected from cattle at 14 diptanks and one commercial farm around the Hluhluwe-Umfolozi Game Reserve, wild animals within Hluhluwe-Umfolozi Game Reserve and tsetse flies from the commercial farm, Hluhluwe-Umfolozi Game Reserve and two other Game Reserves. Trypanosome isolates were grown under laboratory conditions in cattle, rodents and culture medium for molecular characterizations. Overall, a total of 673 cattle, 266 tsetse flies, 141 buffaloes and 6 rhinoceros samples were analyzed. The following observations were made: two species of trypanosomes are present in KZN; T.congolense and T. vivax. The two species were found as single and as mixed infections in cattle. There are two genotypic groups of T. congolense in KZN; the Savannah- and the Kilifi-type. The two genotypic groups were found as mixed infections in cattle and in tsetse flies. Lastly, there are at least five “genomic variants” of Savannah-type T. congolense in KZN. The infection rate in cattle ranged from 5.2-91%; in tsetse flies, 11-97.5% and in wild animals it was 4.3%. Mixed infection of T. congolense and T. vivax were only observed in samples from one diptank. Mixed infections of Savannah- and Kilifi-type T. congolense were observed in samples from Boomerang commercial farm, and in tsetse flies. Copyright / Dissertation (MSc)--University of Pretoria, 2008. / Veterinary Tropical Diseases / unrestricted

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In Uganda, cattle are an important reservoir of Trypanosoma brucei rhodesiense, a parasite that causes human African trypanosomiasis or sleeping sickness. We developed mathematical models to examine the transmission of T. b. rhodesiense by tsetse vector species, Glossina fuscipes fuscipes in a host population that consists of humans, domestic and wild mammals, and reptiles. The models were developed and analysed based on the situation in Tororo district in Southeastern Uganda, where sleeping sickness is endemic and which has a cattle and human population of 40, 000 and 500, 000, respectively. Assuming populations of cattle and humans only, the impact of mass chemoprophylaxis and vector control through insecticide-treated cattle (ITC) is evaluated. Keeping 12% or 82% of the cattle population on insecticides that have an insecticidal killing effect of 100% at all times or trypanocides that have 100% efficacy, respectively, can lead to the control of T. b. rhodesiense in both humans and cattle. Optimal control of T. b. rhodesiense is shown to be achieved through ITC alone or a combination of chemoprophylaxis and ITC, the former being the cheapest control strategy. Allowing for the waning effect of insecticides and including wildhosts, T. b. rhodesiense control can be achieved by keeping 21% or 27% of the cattle population on insecticides through whole-body or restricted application, respectively. Restricting the treatment of insecticides to adult cattle only would require 24% or 33% of the adult cattle population to be kept on insecticides through whole-body or restricted application, respectively, to control T. b. rhodesiense. A cost-effectiveness and benefit-cost analysis of using ITC to control T. b. rhodesiense show that restricted application of insecticides is a cheaper and more beneficial strategy compared to whole-body treatment. The results of the study show that the restricted application of insecticides on cattle provides a cheap, safe and farmer-based strategy for controlling tsetse and trypanosomiasis. / AFRIKAANSE OPSOMMING: In Uganda is beeste ’n belangrike reservoir van Trypanosoma brucei rhodesiense, ’n parasiet wat tripanosomiase of slaapsiekte in mense veroorsaak. Ons het wiskundige modelle ontwikkel wat die oordrag van T. b. Rhodesiense deur tesetse vektor spesies, Glossina fuscipes fuscipes in ’n draer populasie wat bestaan uit mense, mak en wilde diere en reptiele, ondersoek. Die modelle was ontwikkel en geanaliseer gebaseer op die oordrag situasie in die Tororo distrik in Suidoostelike Uganda, ’n gebied waar slaapsiekte endemies is en wat ’n populasie van 40, 000 beeste en 500, 000 mense het. Die impak van massa chemoprofilakse en vektor beheer deur insekdoder-behandelde beeste is gevalueer onder die aanname van bees en mens populasies alleenlik. Beheer oor T. b. Rhodesiense in beide mense en beeste kan verkry word deur of 12% van die bees populasie te behandel met ’n insekdoder wat 100% effektief is ten alle tye of 82% van die bees populasie te behandel met tripanosiedes wat 100% effektief is. Daar is aangetoon dat optimale beheer van T. b. Rhodesiense bereik kan word deur die gebruik van insekdoders alleenlik of ’n kombinasie van insekdoders en chemoprofilakse, hoewel eersgenoemde die goedkoopste strategie is. Wanneer die kwynende effek van insekdoders asook wilde diere as draers in ag geneem word, kan T. b. Rhodesiense beheer verkry word deur 21% van beeste se hele liggaam met insekdoders te behandel of 27% gedeeltelik te behandel. As slegs volwasse beeste met insekdoders behandel word, moet 24% se hele liggaam of 33% gedeeltelik behandel word vir beheer van T. b. Rhodesiense. ’n Koste-effektiwiteit en voordeel-koste analise van insekdoders as beheermaatstaf vir T. b. Rhodesiense toon aan dat gedeeltelike behandeling van die bees se liggaam die goedkoper en meer voordelige strategie is in vergelyking met behandeling van die hele liggaam. Die resultate van die studie wys dat gedeeltelike behandeling van beeste met insekdoders ’n goedkoop, veilige en landbouer-gebaseerde strategie is om tsetse en tripanosomiase te beheer.

Based on field and archival research, Becoming Wilderness analyses the fluid constructs of game preservation and their affect within networks and landscapes to the west of Tarangire National Park, Northern Tanzania from the late 19th Century until the present. The initial query of this thesis is how and why Tarangire comes to be separated as different from its surrounding (on the map and within policy) and what this has entailed for what is ‘within’ and ‘outside’. This thesis is written to add to the understanding of how ‘one of Tanzania’s most spectacular wilderness areas’ was created, in order to problematize and deepen the understanding of the factual people/park conflicts and entanglements existing there today. Through a topological investigation, it shows Tarangire’s transformation from peripheral to central and the simultaneous transformation of peopled landscapes from central to borderlands. Based on interviews, focus groups and archival research the thesis firstly investigates the transformation of peopled landscapes to the west of Tarangire National Park. Secondly it analyses the alternations in the tsetse geography that has previously been claimed to be the root cause behind the creation of the park, pointing to the fluid and relational character of tsetse landscapes. Thirdly, this thesis queries the notion of an ‘imposition of wilderness’ and suggests that vast tracts of Tanzania’s protected areas have in fact gradually become wilderness within heterogeneous networks, rooting themselves in ways that are far more tricky to oppose than had they suddenly been imposed. As such it seeks to contribute to the understanding of the root causes of conservation vs. people conflicts existing today. / People Land and Time in Africa (PLATINA)

Previously, strategy formulation for large-scale eradication of tsetse in southern Africawas dominated by straightforward technical considerations. The current shift to localised control of tsetse-transmitted bovine trypanosomosis has changed the emphasis from the vector to the disease. Nagana remains the main reason for intervening but control methods will differ according to the local situation and interventions will be restricted to those areas where the disease is present. As a result, the technical criteria to be considered will differ substantially from those considered in the planning for large-scale eradication. First, a clear picture of the extent and magnitude of the bovine trypanosomosis problem is required. Second, the selection ofthe most efficient intervention methods will vary according to the local epidemiological situation. Hence, the different epidemiological situations need to be identified and the effectiveness of available control methods needs to be evaluated in each of the situations. Finally, the long-term sustainability of an intervention will depend, to a large extent, upon the socio-economic impact of the disease and perceived benefits accruing from its control. Tsetse-transmitted bovine trypanosomosis occurs in large areas of Malawi, Zambia,Zimbabwe and Namibia. The epidemiology of the disease differs substantially between areas. On the plateau of eastern Zambia, for example, cattle are kept in a tsetse infested area. Because of the encroachment of people and cattle into the tsetse infested area and the concomitant reduction in the number of game animals, tsetse have become highly dependent on cattle as their source of food. As a result, the distribution and density of tsetse is determined largely by the distribution and changes in the distribution or grazing pattern of cattle. Trypanosoma congolense is the main.trypanosome species in tsetse and cattle. The prevalence of congolense-type trypanosomal infections in tsetse undergoes little variations between months and is affected mainly by the average age of the tsetse population. The incidence of bovine trypanosomosis is significantly correlated with the density of the tsetse population.Bovine trypanosomosis is also prevalent in areas where cattle are kept adjacent to a tsetse-infested zone or where tsetse occasionally invade a tsetse-free area. In Malawi,for example, the main foci of bovine trypanosomosis are located adjacent to tsetse infested national parks, game reserves or forest reserves. Bovine trypanosomosis also occurs far outside the known tsetse foci because of the seasonal movement of tsetse,along rivers or because of, often small, undetected tsetse foci. Such foci have been detected in Malawi and in Zimbabwe. In most of the areas, bovine trypanosomosis is caused by T congolense. However, the prevalence of T vivax infections is high in areas where tsetse take a large proportion of feeds on game animals. Please read the full abstract in the section 00 front of this document. / Thesis (PhD)--University of Pretoria, 2000. / Veterinary Tropical Diseases / unrestricted